LMH2832 [TI]

全差分、双路、1.1GHz 数字可变增益放大器;
LMH2832
型号: LMH2832
厂家: TEXAS INSTRUMENTS    TEXAS INSTRUMENTS
描述:

全差分、双路、1.1GHz 数字可变增益放大器

放大器
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LMH2832  
ZHCSF77A JULY 2016REVISED JULY 2016  
LMH2832 全差分双路 1.1GHz 数字可变增益放大器  
1 特性  
3 说明  
1
SPI™单独控制的双通道数字可变增益放大器  
LMH2832 是一款高线性度双通道数字可变增益放大器  
(DVGA)  
(DVGA),适用于高速信号链和数据采集系统。  
LMH2832 已经过优化,可实现高带宽、低失真和低噪  
声等特性,因此非常适合用作双路 14 位模数转换器  
(ADC) 的驱动器。此器件包含一个固定增益模块和一  
个可变衰减器,总增益为 30dB,最大衰减为 39dB。  
增益范围为 –9dB 30dB,增益步长为 1dB,增益精  
度为 ±0.2dB。输入阻抗可分别使用 1:3Ω 1:2Ω 比率  
平衡-非平衡转换器来轻松匹配 50Ω 75Ω 系统。  
LMH2832 设计用于驱动通用 ADC,而且满足电缆数  
据服务接口规范 (DOCSIS) 3.0 32 正交振幅调制  
(QAM) 载波和 DOCSIS 3.1 宽带正交频分多路复用  
(OFDM) 系统的要求。凭借优异的 NF (6.5dB) 和线性  
度,LMH2832 可遵循 DOCSIS 规范执行。掉电状态  
下的静态电流低于每通道 5mA,而运行期间的典型流  
耗为每通道 105mA。  
5V 单电源  
–3dB 带宽:1.1GHz(最大增益)  
平滑带宽响应:300MHz  
通道间增益匹配:±0.05dB  
通道间相位匹配:±0.1°  
增益:  
-9dB 30dB  
1dB 步长 ±0.2dB  
输出三阶截断点 (OIP3):  
300MHz 时为 43dBm  
200MHz 时为 51dBm  
噪声系数 (NF):  
300MHzZIN = 150Ω 时为 6.5dB(最大增益)  
可调功耗:  
每通道 90mA 108mA  
器件信息(1)  
节能、掉电特性:  
器件型号  
LMH2832  
封装  
VQFN (40)  
封装尺寸(标称值)  
每通道 IQ < 4.5mA  
6.00mm x 6.00mm  
掉电引脚和 SPI 可编程性  
(1) 要了解所有可用封装,请见数据表末尾的可订购产品附录。  
300MHz 时的输入回波损耗:  
17dB (RS = 150Ω)  
2 应用  
DOCSIS 3.1 CMTS 上行直接采样接收器  
CATV 调制解调器信号调节  
可编程增益 IF 放大器  
通用 RFIF 增益级  
ADC 驱动器  
输出三阶截断点 (OIP3) 性能  
60  
55  
50  
45  
40  
35  
30  
25  
Channel A  
Channel B  
0
50 100 150 200 250 300 350 400 450 500 550 600  
Frequency (MHz)  
D005  
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,  
intellectual property matters and other important disclaimers. PRODUCTION DATA.  
English Data Sheet: SBOS709  
 
 
 
 
LMH2832  
ZHCSF77A JULY 2016REVISED JULY 2016  
www.ti.com.cn  
目录  
9.1 Overview ................................................................. 19  
9.2 Functional Block Diagram ....................................... 19  
9.3 Feature Description................................................. 19  
9.4 Device Functional Modes........................................ 21  
9.5 Programming........................................................... 21  
9.6 Register Maps......................................................... 24  
10 Application and Implementation........................ 29  
10.1 Application Information.......................................... 29  
10.2 Typical Applications .............................................. 32  
10.3 Do's and Don'ts..................................................... 35  
11 Power Supply Recommendations ..................... 35  
11.1 Split Supplies ........................................................ 35  
11.2 Supply Decoupling ................................................ 35  
12 Layout................................................................... 36  
12.1 Layout Guidelines ................................................. 36  
12.2 Layout Example .................................................... 36  
13 器件和文档支持 ..................................................... 37  
13.1 器件支持 ............................................................... 37  
13.2 文档支持 ............................................................... 37  
13.3 接收文档更新通知 ................................................. 37  
13.4 社区资源................................................................ 37  
13.5 ....................................................................... 37  
13.6 静电放电警告......................................................... 38  
13.7 Glossary................................................................ 38  
14 机械、封装和可订购信息....................................... 38  
1
2
3
4
5
6
7
特性.......................................................................... 1  
应用.......................................................................... 1  
说明.......................................................................... 1  
修订历史记录 ........................................................... 2  
Device Comparison Table..................................... 3  
Pin Configuration and Functions......................... 3  
Specifications......................................................... 5  
7.1 Absolute Maximum Ratings ...................................... 5  
7.2 ESD Ratings.............................................................. 5  
7.3 Recommended Operating Conditions....................... 5  
7.4 Thermal Information.................................................. 5  
7.5 Electrical Characteristics........................................... 6  
7.6 Timing Requirements: SPI ........................................ 8  
7.7 Typical Characteristics.............................................. 9  
Parameter Measurement Information ................ 16  
8.1 Setup Diagrams ...................................................... 16  
8.2 ATE Testing and DC Measurements ...................... 17  
8.3 Frequency Response.............................................. 17  
8.4 Distortion................................................................. 17  
8.5 Noise Figure............................................................ 17  
8
8.6 Pulse Response, Slew Rate, and Overdrive  
Recovery.................................................................. 18  
8.7 Power-Down............................................................ 18  
8.8 Crosstalk, Gain Matching, and Phase Matching..... 18  
8.9 Output Measurement Reference Points.................. 18  
Detailed Description ............................................ 19  
9
4 修订历史记录  
注:之前版本的页码可能与当前版本有所不同。  
Changes from Original (July 2016) to Revision A  
Page  
已发布为量产数................................................................................................................................................................... 1  
2
Copyright © 2016, Texas Instruments Incorporated  
 
LMH2832  
www.ti.com.cn  
ZHCSF77A JULY 2016REVISED JULY 2016  
5 Device Comparison Table  
Table 1. DVGA Device Comparison  
DEVICE  
LMH6401  
LHM6517  
LMH6521  
LMH6881  
MAX GAIN, BW  
DISTORTION  
NOISE FIGURE  
26 dB, 4.5 GHz  
22 dB, 1.2 GHz  
26 dB, 1.2 GHz  
26 dB, 2.4 GHz  
43-dBm OIP3 at 200 MHz, –80-dBc HD3 at 200 MHz  
43-dBm OIP3 at 200 MHz, –74-dBc HD3 at 200 MHz  
49-dBm OIP3 at 200 MHz, –84-dBc HD3 at 200 MHz  
42-dBm OIP3 at 200 MHz, –76-dBc HD3 at 200 MHz  
7.7 dB  
5.5 dB  
7.3 dB  
9.7 dB  
6 Pin Configuration and Functions  
RHA Package  
40-Pin VQFN  
Top View  
INMA  
1
2
3
4
5
6
7
8
9
10  
30  
29  
28  
27  
OUTMA  
GND  
VCC  
GND  
VCC  
CS  
VCC  
SCLK,Thermal_pad  
26  
VCC  
Thermal  
Pad  
SDI  
SDO  
VCC  
GND  
INMB  
25  
24  
23  
22  
21  
VCC  
VCC  
VCC  
GND  
OUTMB  
Not to scale  
Copyright © 2016, Texas Instruments Incorporated  
3
LMH2832  
ZHCSF77A JULY 2016REVISED JULY 2016  
www.ti.com.cn  
Pin Functions  
PIN  
I/O  
DESCRIPTION  
NAME  
CS  
NO.  
4
I
I
Serial interface enable, active low  
Analog ground  
GND  
2, 9, 12, 19, 22, 29, 32, 39  
INMA  
INMB  
INPA  
INPB  
OUTMA  
OUTMB  
OUTPA  
OUTPB  
PDB  
1
I
Negative differential input, channel A  
Negative differential input, channel B  
Positive differential input, channel A  
Positive differential input, channel B  
Negative differential output, channel A  
Negative differential output, channel B  
Positive differential output, channel A  
Positive differential output, channel B  
Power-down control, channel B (logic high = power-down)  
Power-down control, channel A (logic high = power-down)  
Serial interface clock input  
10  
40  
11  
30  
21  
31  
20  
15  
36  
5
I
I
I
O
O
O
O
I
PDA  
I
SCLK  
SDI  
I
6
I
Serial interface data input  
SDO  
7
O
Serial interface data output  
3, 8, 13, 14, 16, 17, 18, 23, 24, 25,  
26, 27, 28, 33, 34, 35, 37, 38  
VCC  
I
Analog voltage supply  
Connected to ground  
Thermal pad  
4
Copyright © 2016, Texas Instruments Incorporated  
LMH2832  
www.ti.com.cn  
ZHCSF77A JULY 2016REVISED JULY 2016  
7 Specifications  
7.1 Absolute Maximum Ratings  
over operating free-air temperature range (unless otherwise noted)(1)  
MIN  
–0.5  
–0.5  
–0.5  
–0.3  
MAX  
5.5  
5.5  
5.5  
2
UNIT  
V
Power supply  
Input applied to analog inputs  
Voltage applied to input pins  
Digital input/output voltage range  
Operating junction temperature, TJ  
Storage temperature, Tstg  
INPA, INMA, INPB, INMB  
V
V
V
125  
125  
°C  
°C  
–40  
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings  
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended  
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.  
7.2 ESD Ratings  
VALUE  
±2000  
±1000  
UNIT  
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)  
Charged device model (CDM), per JEDEC specification JESD22-C101(2)  
V(ESD)  
Electrostatic discharge  
V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.  
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.  
7.3 Recommended Operating Conditions  
over operating free-air temperature range (unless otherwise noted)  
MIN  
4.75  
–40  
NOM  
MAX  
UNIT  
VS  
Power-supply voltage  
5
5.25  
85  
V
Specified operating temperature range  
°C  
7.4 Thermal Information  
LMH2832  
THERMAL METRIC(1)  
RHA (VQFN)  
40 PINS  
29.5  
UNIT  
RθJA  
Junction-to-ambient thermal resistance  
°C/W  
°C/W  
°C/W  
°C/W  
°C/W  
°C/W  
RθJC(top)  
RθJB  
Junction-to-case (top) thermal resistance  
Junction-to-board thermal resistance  
20.4  
6.6  
ψJT  
Junction-to-top characterization parameter  
Junction-to-board characterization parameter  
Junction-to-case (bottom) thermal resistance  
0.3  
ψJB  
6.5  
RθJC(bot)  
2.3  
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application  
report (SPRA953).  
Copyright © 2016, Texas Instruments Incorporated  
5
LMH2832  
ZHCSF77A JULY 2016REVISED JULY 2016  
www.ti.com.cn  
7.5 Electrical Characteristics  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with a transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
TEST  
PARAMETER  
AC PERFORMANCE  
TEST CONDITIONS  
MIN  
TYP  
MAX UNIT  
LEVEL(1)  
G = 30 dB, VO = 2 VPP  
1140  
2350  
300  
–88  
–76  
–63  
–58  
–94  
–90  
–81  
–75  
C
C
C
C
C
C
C
C
C
C
C
Large-signal,  
–3-dB bandwidth  
LSBW  
BW  
MHz  
MHz  
G = 0 dB, VO = 2 VPP  
Bandwidth for 0.1-dB flatness  
f = 100 MHz, VO = 2 VPP  
f = 200 MHz, VO = 2 VPP  
f = 300 MHz, VO = 2 VPP  
f = 450 MHz, VO = 2 VPP  
f = 100 MHz, VO = 2 VPP  
f = 200 MHz, VO = 2 VPP  
f = 300 MHz, VO = 2 VPP  
f = 450 MHz, VO = 2 VPP  
Second-order harmonic  
distortion  
HD2  
dBc  
Third-order harmonic  
distortion  
HD3  
dBc  
dBc  
f = 100 MHz, tone spacing = 2 MHz,  
POUT(2) = 0 dBm per tone  
–106  
C
Third-order intermodulation  
distortion  
IMD3  
f = 200 MHz, tone spacing = 2 MHz  
f = 300 MHz, tone spacing = 2 MHz  
–102  
–86  
C
C
f = 100 MHz, tone spacing = 2 MHz,  
POUT = 0 dBm per tone  
53  
51  
43  
C
C
C
Output third-order intercept  
point  
f = 200 MHz, tone spacing = 2 MHz,  
POUT = 0 dBm per tone  
OIP3  
dBm  
dBm  
f = 300 MHz, tone spacing = 2 MHz,  
POUT = 0 dBm per tone  
f = 100 MHz, RL = 150 Ω  
f = 200 MHz, RL = 150 Ω  
f = 300 MHz, RL = 150 Ω  
Ri = 150 Ω, f = 300 MHz, max gain  
16  
16  
C
C
C
C
C
C
C
P1dB  
NF  
1-dB compression point  
Noise figure  
16.5  
6.5  
dB  
nV/Hz  
dB  
Output-referred voltage noise f = 300 MHz, max gain  
47.7  
17  
S11  
S22  
Input return loss  
Reverse Isolation  
f = 300 MHz  
Including input transformer, f < 300 MHz  
f = 300 MHz, channel A to B  
f = 300 MHz, channel B to A  
53  
dB  
–77  
–81  
Channel-to-channel crosstalk  
dB  
C
Channel-to-channel phase  
matching  
f = 200 MHz  
f = 200 MHz  
±0.1  
°
C
C
Channel-to-channel gain  
matching  
±0.05  
dB  
GAIN PARAMETERS  
Maximum voltage gain  
f = dc, gain code = 00h  
f = dc, gain code = 27h  
29.5  
–9.5  
30  
–9  
39  
1
30.5  
–8.5  
dB  
dB  
dB  
dB  
dB  
dB  
ns  
A
A
C
A
A
A
C
Minimum voltage gain  
Gain range  
Gain step size  
Between any two adjacent gain settings  
For any gain value  
0.75  
–0.5  
–1  
1.25  
0.5  
1
EG  
Gain error  
0
Cumulative gain error  
Gain step transition time  
Referenced to max gain  
6
(1) Test levels: (A) 100% tested at 25°C. Overtemperature limits by characterization and simulation. (B) Limits set by characterization and  
simulation. (C) Typical value only for information.  
(2) POUT is the signal tone power at the output of the device.  
6
Copyright © 2016, Texas Instruments Incorporated  
 
LMH2832  
www.ti.com.cn  
ZHCSF77A JULY 2016REVISED JULY 2016  
Electrical Characteristics (continued)  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with a transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
TEST  
PARAMETER  
TEST CONDITIONS  
MIN  
TYP  
MAX UNIT  
LEVEL(1)  
ANALOG INPUT CHARACTERISTICS  
zin  
Input resistance  
f = dc, differential  
Differential  
135  
150  
0.6  
75  
165  
Ω
pF  
Ω
A
C
A
Cin  
Input capacitance  
Single-ended input resistance f = dc  
67.5  
82.5  
Single-ended input  
capacitance  
1.2  
pF  
C
VICM  
VIL  
Input common-mode voltage  
Internally biased to mid-supply  
–0.2  
0.2  
V
V
V
A
C
C
Low-level input voltage range Differential gain shift < 1 dB  
High-level input voltage range Differential gain shift < 1 dB  
(VS–) + 1.5  
(VS+) – 1.5  
VIH  
ANALOG OUTPUT CHARACTERISTICS  
zo  
Output resistance  
Differential  
20  
Ω
C
A
Low-level output voltage  
range  
VOL  
VS = 5 V, GND = 0 V  
1.15  
1.25  
6.4  
V
High-level output voltage  
range  
VOH  
VS = 5 V, GND = 0 V  
3.75  
5
3.85  
V
A
TA = 25°C  
5.4  
5.4  
56  
A
B
C
Maximum output voltage  
swing  
VOM  
V
TA = –40°C to +85°C  
CMRR  
Common-mode rejection ratio  
dB  
POWER SUPPLY  
VS  
Supply voltage  
4.75  
102  
5.0  
105  
90  
5.25  
108  
V
A
A
C
C
C
Default current, default bias setting  
Quiescent current per channel Min current, lowest power setting  
Max current, highest bias setting  
IQ  
mA  
dB  
108  
–48  
±PSRR  
Power-supply rejection ratio(3) Gain = 30 dB  
POWER-DOWN(4)  
TA = 25°C  
2.5  
6
A
B
A
Power-down quiescent current  
(per channel)  
mA  
TA = –40°C to +85°C  
6.5  
Power-down bias current  
–2  
–1  
55  
µA  
ns  
Time to VO = 90% of final value,  
gain = 0 dB, VI = 2 V  
Turn-on time delay  
Turn-off time delay  
C
Time to VO = 10% of original value,  
gain = 0 dB, VI = 2 V  
110  
–67  
ns  
C
C
Forward isolation in PD mode f = 300 MHz  
DIGITAL INPUTS/OUTPUTS  
dB  
VIH  
VIL  
High-level input voltage  
Low-level input voltage  
1.4  
–0.3  
1.65  
1.55  
2
V
V
A
A
A
A
A
A
0.8  
IOH = –100 µA  
IOH = –2 mA  
IOL = 100 µA  
IOL = 2 mA  
VOH  
High-level output voltage  
Low-level output voltage  
V
V
0.1  
0.2  
VOL  
(3) PSRR is defined with respect to a differential output.  
(4) The device power-down function can be controlled by the PDx pins or by the power-down register accessible from the SPI interface.  
Copyright © 2016, Texas Instruments Incorporated  
7
LMH2832  
ZHCSF77A JULY 2016REVISED JULY 2016  
www.ti.com.cn  
7.6 Timing Requirements: SPI  
MIN  
TYP  
25  
10  
10  
3
MAX  
UNIT  
MHz  
ns  
fS_C  
tPH  
SCLK frequency(1)  
SCLK pulse duration, high  
SCLK pulse duration, low  
SDI setup  
0
50  
tPL  
ns  
tSU  
ns  
tH  
SDO hold  
3
ns  
tIZ  
SDO tri-state  
3
ns  
tODZ  
tOZD  
tOD  
tCSS  
tCSH  
tIAG  
SDO driven to tri-state(2)  
SDO tri-state to driven  
SDO output delay(2)  
CS setup(3)  
0
0
0
3
10  
2
20  
5
ns  
ns  
10  
5
12  
ns  
ns  
CS hold  
3
ns  
Inter-access gap  
20  
ns  
(1) Tested on the automated test equipment (ATE) only up to 25 MHz.  
(2) Referenced to the negative edge of SCLK.  
(3) Referenced to the positive edge of SCLK.  
8
Copyright © 2016, Texas Instruments Incorporated  
 
LMH2832  
www.ti.com.cn  
ZHCSF77A JULY 2016REVISED JULY 2016  
7.7 Typical Characteristics  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
32  
28  
24  
20  
16  
12  
8
31  
30.8  
30.6  
30.4  
30.2  
30  
f = 50 MHz  
f = 100 MHz  
f = 200 MHz  
f = 300 MHz  
f = 400 MHz  
f = 500 MHz  
29.8  
29.6  
29.4  
29.2  
29  
4
0
-4  
-8  
-12  
-16  
28.8  
1
10  
100  
1000  
8000  
-40  
-20  
0
20  
40  
60  
80  
100110  
Frequency (MHz)  
Temperature (°C)  
D001  
D025  
VO = 2 VPP  
Figure 1. Voltage Gain vs Frequency (1-dB Gain Steps)  
Figure 2. Gain Flatness vs Temperature  
0
0.1  
0.2  
Gain Matching Error (dB)  
Phase Matching Error (°)  
-5  
-10  
-15  
-20  
-25  
-30  
-35  
-40  
-45  
-50  
-55  
-60  
0.05  
0
0.1  
0
-0.05  
-0.1  
-0.1  
-0.2  
1
10  
100  
1000  
3000  
-9 -6 -3  
0
3
6
9
12 15 18 21 24 27 30  
Frequency (MHz)  
Voltage Gain (dB)  
D008  
D034  
Differential input impedance (ZIN) = 150 Ω, all gain settings  
f = 200 MHz  
Figure 3. Input Return Loss vs Frequency  
Figure 4. Channel-to-Channel Mismatch Error  
60  
60  
-40'C  
27'C  
90'C  
Av = 30 dB  
Av = 22 dB  
Av = 14 dB  
Av = 6 dB  
Av = 2 dB  
Av = -2 dB  
55  
50  
45  
40  
35  
30  
25  
55  
105'C  
50  
45  
40  
35  
30  
25  
0
50 100 150 200 250 300 350 400 450 500 550 600  
Frequency (MHz)  
0
50 100 150 200 250 300 350 400 450 500 550 600  
Frequency (MHz)  
D002  
D004  
POUT = 0 dBm per tone  
POUT = 0 dBm per tone  
Figure 5. OIP3 vs Frequency and Voltage Gain  
Figure 6. OIP3 vs Frequency and Temperature  
Copyright © 2016, Texas Instruments Incorporated  
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LMH2832  
ZHCSF77A JULY 2016REVISED JULY 2016  
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Typical Characteristics (continued)  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
60  
55  
50  
45  
40  
35  
30  
25  
60  
55  
50  
45  
40  
35  
30  
25  
Av = 30 dB  
Av = 22 dB  
Av = 14 dB  
Av = 6 dB  
Av = 2 dB  
Av = -2 dB  
Channel A  
Channel B  
0
2
4
6
8
10  
12  
14  
0
50 100 150 200 250 300 350 400 450 500 550 600  
Frequency (MHz)  
POUT per tone (dBm)  
D003  
D005  
f = 200 MHz  
POUT = 0 dBm per tone  
Figure 7. OIP3 vs Output Power  
Figure 8. OIP3 Channel Comparison  
46  
45  
44  
43  
42  
41  
40  
58  
57  
56  
55  
54  
53  
52  
51  
50  
VS = 4.5 V  
VS = 4.75 V  
VS = 5 V  
VS = 4.5 V  
VS = 4.75 V  
VS = 5 V  
VS = 5.25 V  
VS = 5.25 V  
-40  
-20  
0
20  
40  
60  
80  
100110  
-40  
-20  
0
20  
40  
60  
80  
100110  
Temperature (°C)  
Temperature (°C)  
D006  
D007  
POUT = 0 dBm per tone  
POUT = 0 dBm per tone  
Figure 9. OIP3 vs Temperature and Supply Voltage  
(f = 200 MHz)  
Figure 10. OIP3 vs Temperature and Supply Voltage  
(f = 300 MHz)  
0
56  
55  
54  
53  
52  
51  
50  
49  
48  
47  
46  
IMD2 (dBc)  
IMD3 (dBc)  
-10  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
Bias Setting = 00h  
Bias Setting = 02h  
Bias Setting = 08h  
Bias Setting = 20h  
Bias Setting = 80h  
-90  
-100  
-110  
-120  
-40  
-20  
0
20  
40  
60  
80  
100110  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
Temperature (°C)  
D038  
D039  
POUT = 0 dBm per tone  
POUT = 0 dBm per tone  
Figure 11. OIP3 vs Temperature and Bias Setting  
(f = 200 MHz)  
Figure 12. Intermodulation Distortion vs Frequency  
10  
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LMH2832  
www.ti.com.cn  
ZHCSF77A JULY 2016REVISED JULY 2016  
Typical Characteristics (continued)  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
50  
45  
40  
35  
30  
25  
20  
15  
10  
5
12  
11  
10  
9
f = 50 MHz  
f = 100 MHz  
f = 200 MHz  
f = 300 MHz  
25°C  
8
7
6
5
4
-9 -6 -3  
0
3
6
9
12 15 18 21 24 27 30  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
Voltage Gain (dB)  
D011  
D022  
ZIN = 150 Ω  
Figure 13. Noise Figure vs Voltage Gain  
Figure 14. Noise Figure vs Frequency  
0
0
Gain = 30 dB  
Gain = 22 dB  
Gain = 14 dB  
Gain = 6 dB  
Gain = 2 dB  
Gain = -2 dB  
Gain = 30 dB  
Gain = 22 dB  
Gain = 14 dB  
Gain = 6 dB  
Gain = 2 dB  
Gain = -2 dB  
-10  
-20  
-10  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
-90  
-100  
-30  
-40  
-50  
-60  
-70  
-80  
-90  
-100  
-110  
-120  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
D012  
D013  
VO = 2 VPP  
VO = 2 VPP  
Figure 15. HD2 vs Frequency and Gain Settings  
Figure 16. HD3 vs Frequency and Gain Settings  
0
-10  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
-90  
-100  
0
-10  
-40°C  
25°C  
90°C  
-40°C  
25°C  
90°C  
-20  
105°C  
105°C  
-30  
-40  
-50  
-60  
-70  
-80  
-90  
-100  
-110  
-120  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
D014  
D015  
VO = 2 VPP  
VO = 2 VPP  
Figure 17. HD2 vs Frequency and Temperature  
Figure 18. HD3 vs Frequency and Temperature  
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Typical Characteristics (continued)  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
0
-50  
-55  
-60  
-65  
-70  
-75  
-80  
-85  
-90  
-95  
-100  
Channel A (HD2)  
Channel A (HD3)  
Channel B (HD2)  
Channel B (HD3)  
VS = 4.5 V (HD2)  
VS = 4.5 V (HD3)  
VS = 5 V (HD2)  
VS = 5 V (HD3)  
VS = 5.25 V (HD2)  
VS = 5.25 V (HD3)  
-10  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
-90  
-100  
-110  
-120  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
-40  
-20  
0
20  
40  
60  
80  
100110  
Temperature (°C)  
D040  
D016  
VO = 2 VPP  
Figure 19. Harmonic Distortion Between Channels  
Figure 20. Harmonic Distortion vs Temperature and  
Supply Voltage (100 MHz)  
-50  
-55  
-60  
-65  
-70  
-75  
-80  
-85  
-90  
-95  
-100  
-40  
VS = 4.5 V (HD2)  
VS = 4.5 V (HD3)  
VS = 5 V (HD2)  
VS = 5 V (HD3)  
VS = 5.25 V (HD2)  
VS = 5.25 V (HD3)  
Gain = 30 dB  
Gain = 22 dB  
Gain = 14 dB  
Gain = 6 dB  
Gain = 2 dB  
-50  
-60  
-70  
-80  
-90  
-100  
-40  
-20  
0
20  
40  
60  
80  
100110  
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
5.5  
Temperature (°C)  
Differential Output Swing (VPP  
)
D017  
D018  
VO = 2 VPP  
Figure 21. Harmonic Distortion vs Temperature and  
Supply Voltage (200 MHz)  
Figure 22. HD2 vs Differential Output Swing (100 MHz)  
-40  
-30  
Gain = 30 dB  
Gain = 22 dB  
Gain = 14 dB  
Gain = 6 dB  
Gain = 2 dB  
Gain = 30 dB  
Gain = 22 dB  
Gain = 14 dB  
Gain = 6 dB  
Gain = 2 dB  
-40  
-50  
-60  
-50  
-60  
-70  
-70  
-80  
-80  
-90  
-90  
-100  
-100  
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
5.5  
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
5.5  
Differential Output Swing (VPP  
)
Differential Output Swing (VPP  
)
D019  
D020  
Figure 23. HD3 vs Differential Output Swing (100 MHz)  
Figure 24. HD2 vs Differential Output Swing (200 MHz)  
12  
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Typical Characteristics (continued)  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
-30  
22  
20  
18  
16  
14  
12  
10  
Gain = 30 dB  
Gain = 22 dB  
Gain = 14 dB  
Gain = 6 dB  
Gain = 2 dB  
VS = 4.5 V  
VS = 5 V  
VS = 5.25 V  
-40  
-50  
-60  
-70  
-80  
-90  
-100  
-110  
0.5  
1
1.5  
2
2.5  
3
3.5  
4
4.5  
5
5.5  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
Differential Output Swing (VPP  
)
D021  
D023  
Figure 25. HD3 vs Differential Output Swing (200 MHz)  
Figure 26. Output P1dB Compression vs Frequency  
20  
80  
70  
60  
50  
40  
30  
20  
10  
0
VS = 4.5 V  
VS = 5 V  
VS = 5.25 V  
19  
18  
17  
16  
15  
14  
-40  
-20  
0
20  
40  
60  
80  
100110  
1
10  
100  
1000  
8000  
Temperature (°C)  
Frequency (MHz)  
D024  
D033  
Sdd21 / Scc21  
Figure 27. Output P1dB Compression vs Temperature  
Figure 28. CMRR vs Frequency  
0
-40  
-50  
Channel A to B  
Channel B to A  
-10  
-20  
-30  
-40  
-50  
-60  
-70  
-80  
-60  
-70  
-80  
-90  
-100  
-110  
1
10  
100  
1000  
8000  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
Frequency (MHz)  
D035  
D037  
Scd21 / Sdd21  
Figure 29. Output Balance Error vs Frequency  
Figure 30. Channel-to-Channel Isolation vs Frequency  
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Typical Characteristics (continued)  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
0.15  
6
f = 100 MHz  
f = 200 MHz  
f = 300 MHz  
f = 100 MHz  
f = 200 MHz  
f = 300 MHz  
0.1  
4
0.05  
0
2
0
-0.05  
-0.1  
-0.15  
-2  
-4  
-6  
-9 -6 -3  
0
3
6
9
12 15 18 21 24 27 30  
-9 -6 -3  
0
3
6
9
12 15 18 21 24 27 30  
Voltage Gain (dB)  
Voltage Gain (dB)  
D009  
D010  
Figure 31. Cumulative Gain Step Error vs Voltage Gain  
Figure 32. Cumulative Phase Step Error vs Voltage Gain  
200  
2.4  
2.5  
R (W)  
jX (W)  
|Z| (W)  
Power Down Pin  
Output  
2
2
150  
100  
50  
1.6  
1.2  
0.8  
0.4  
0
1.5  
1
0.5  
0
0
-50  
-100  
-0.5  
-0.4  
-1  
1
10  
100  
1000 2000  
Time (50 ns/div)  
Frequency (MHz)  
D036  
D026  
Figure 33. Output Impedance vs Frequency  
Figure 34. Power-Down Transition Response  
2.4  
2.4  
2
2.4  
2
2.4  
SCLK  
Output  
SCLK  
Output  
2
1.6  
1.2  
0.8  
0.4  
0
2
1.6  
1.2  
0.8  
0.4  
0
1.6  
1.2  
0.8  
0.4  
0
1.6  
1.2  
0.8  
0.4  
0
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
Time (10 ns/div)  
Time (10 ns/div)  
D027  
D028  
Figure 35. Gain Switching Response (AV = 30 dB to 22 dB)  
Figure 36. Gain Switching Response (AV = 22 dB to 30 dB)  
14  
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Typical Characteristics (continued)  
at TA = 25°C, VS+ = 5 V, Ri = 75 Ω, RL = 150 Ω, maximum gain (1:2-Ω ratio transformer plus 30-dB DVGA gain), f = 5 MHz to  
300 MHz, VO converted to single-ended (SE) measurement with transformer, and default current setting (unless otherwise  
noted); upon power-up, gain is set to mid-range  
2.4  
2.4  
2.4  
2.4  
SCLK  
Output  
SCLK  
Output  
2
2
2
2
1.6  
1.2  
0.8  
0.4  
0
1.6  
1.2  
0.8  
0.4  
0
1.6  
1.2  
0.8  
0.4  
0
1.6  
1.2  
0.8  
0.4  
0
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
Time (10 ns/div)  
Time (10 ns/div)  
D029  
D030  
Figure 37. Gain Switching Response (AV = 30 dB to 14 dB)  
Figure 38. Gain Switching Response (AV = 14 dB to 30 dB)  
2.4  
2.4  
2
2.4  
2.4  
2
SCLK  
Output  
SCLK  
Output  
2
1.6  
1.2  
0.8  
0.4  
0
2
1.6  
1.2  
0.8  
0.4  
0
1.6  
1.2  
0.8  
0.4  
0
1.6  
1.2  
0.8  
0.4  
0
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
-0.4  
-0.8  
-1.2  
Time (10 ns/div)  
Time (10 ns/div)  
D031  
D032  
Figure 39. Gain Switching Response (AV = 30 dB to 6 dB)  
Figure 40. Gain Switching Response (AV = 6 dB to 30 dB)  
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8 Parameter Measurement Information  
8.1 Setup Diagrams  
Figure 41 to Figure 44 illustrate various test setup diagrams using the LMH2832 evaluation module (EVM).  
LMH2832EVM-50  
VS+ = 5 V  
Vector Network  
Analyzer  
Vector Network  
Analyzer  
0.1 µF  
0.1 µF  
0.1 µF  
0.1 µF  
50  
10 ꢀ  
50 ꢀ  
15 ꢀ  
15 ꢀ  
Port 1  
Port 3  
SMA  
SMA  
SMA  
Port 2  
Port 4  
INPx  
INMx  
OUTPx  
OUTMx  
+
-
+
-
½ LMH2832  
OUT_AMP  
10 ꢀ  
OUT_LOAD  
SMA  
50 ꢀ  
50 ꢀ  
Test Equipment  
Test Equipment  
with 50-Ω Inputs/Outputs  
with 50-Ω Inputs/Outputs  
SPI  
USB  
GND  
Copyright © 2016, Texas Instruments Incorporated  
Figure 41. Frequency Response Differential Test Setup  
LMH2832EVM-75  
VS+ = 5 V  
zo = 50 , 1:2  
ETC1-1-13T  
(1:1, zo = 50 )  
F-Connector  
BMP5075  
0.1 µF  
0.1 µF  
0.1 µF  
0.1 µF  
10-  
50 ꢀ  
40 ꢀ  
40 ꢀ  
INPx  
INMx  
OUTPx  
OUTMx  
0º  
50 ꢀ  
+
SMA  
½ LMH2832  
OUT_AMP  
-
180º  
BMP5075  
F-Connector  
Spectrum Analyzer  
10-ꢀ  
with 50-Ω Inputs  
Signal Generator  
with 50-Ω Outputs  
Band-Pass  
Filter  
ZFSCJ-2-1-S+  
SPI  
USB  
75-Ω Reference  
50-Ω Reference  
GND  
Copyright © 2016, Texas Instruments Incorporated  
Figure 42. Single-Tone Harmonic Distortion Test Setup  
LMH2832EVM-75  
VS+ = 5 V  
50  
Signal Generator  
with 50-Ω Outputs  
MABA011033  
F-Connector  
ETC1-1-13T  
(1:1, zo = 50 )  
0.1 µF  
0.1 µF  
0.1 µF  
0.1 µF  
(1:2, zo = 75 )  
10 ꢀ  
50 ꢀ  
ZFSCJ-2-1  
or  
ZFSCJ-2-4  
40 ꢀ  
40 ꢀ  
6-dB  
Attenuation  
Pads  
INPx  
INMx  
OUTPx  
OUTMx  
Band-Pass  
Filter  
BMP5075  
+
-
SMA  
½ LMH2832  
OUT_AMP  
Spectrum Analyzer  
with 50-Ω Inputs  
10 ꢀ  
50 ꢀ  
50-Ω Reference  
75-Ω Reference  
SPI  
USB  
Signal Generator  
GND  
with 50-Ω Outputs  
Copyright © 2016, Texas Instruments Incorporated  
Figure 43. Two-Tone Linearity Test Setup (OIP3, OIP2)  
16  
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Setup Diagrams (continued)  
LMH2832EVM-50  
VS+ = 5 V  
MABA011038  
(1:3, zo = 50 )  
ETC1-1-13T  
(1:1, zo = 50 )  
0.1 µF  
0.1 µF  
0.1 µF  
10  
50 ꢀ  
50 ꢀ  
40 ꢀ  
40 ꢀ  
INPx  
INMx  
OUTPx  
OUTMx  
346B  
Noise Source  
SMA  
½ LMH2832  
SMA  
Agilent E4443A  
with 50-Ω Outputs  
Agilent E4443A  
with 50-Ω Inputs  
10 ꢀ  
0.1 µF  
SPI  
USB  
GND  
Copyright © 2016, Texas Instruments Incorporated  
Figure 44. Noise Figure Test Setup  
8.2 ATE Testing and DC Measurements  
All production testing and dc parameters are measured on automated test equipment (ATE) capable of dc  
measurements only. Some measurements (such as voltage gain) are referenced to the output of the internal  
amplifier and do not include losses attributed to the on-chip output resistors. The Electrical Characteristics values  
specify these conditions. When the measurement is referred to the amplifier output, the output resistors are not  
included in the measurement. If the measurement is referred to the device pins, then the output resistor loss is  
included in the measurement.  
8.3 Frequency Response  
This test is done by running an S-parameter sweep on a 4-port differential network analyzer using the standard  
EVM with no baluns; see Figure 41. The inputs and outputs of the EVM are connected to the network analyzer  
using 75-coaxial cables with the input ports set to a characteristic impedance of 75 Ω, and the output ports set  
to a characteristic impedance of 50 Ω.  
The frequency response test with capacitive load is done by soldering the capacitor across the LMH2832 output  
pins. In this configuration, the on-chip, 10-Ω resistors on each output leg isolate the capacitive load from the  
amplifier output pins.  
8.4 Distortion  
The standard EVM is used for measuring both the single-tone harmonic distortion and two-tone intermodulation  
distortion; see Figure 42 and Figure 43, respectively. The distortion is measured with differential input signals to  
the LMH2832. In order to interface with 50-Ω, single-ended test equipment, 50-Ω to 75-Ω impedance matching  
pads followed by external baluns (1:2, zo = 75 Ω) are required between the EVM output ports and the test  
equipment. These baluns are used to combine two single tones in the two-tone test plots as well as to convert  
the single-ended input to differential output for harmonic distortion tests. The use of 6-dB attenuator pads on both  
the inputs and outputs is recommended to provide a balanced match between the external balun and the EVM.  
8.5 Noise Figure  
This test is done by matching the input of the LMH2832 to a 50-Ω noise source using a 50-Ω to 75-Ω impedance  
transformation pad followed by a 1:2 balun (Figure 44), with the noise figure being referred to the input  
impedance (RS = 150 Ω). As noted in Figure 44, a Keysight Technologies™ E4443A with NF features is used for  
the testing.  
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8.6 Pulse Response, Slew Rate, and Overdrive Recovery  
For time-domain measurements, the standard EVM is driven through an impedance transformation pad and a  
balun again to convert a single-ended output from the test equipment to the differential inputs of the LMH2832.  
The differential outputs are directly connected to the oscilloscope inputs, with the differential signal response  
calculated using trace math from the two separate oscilloscope inputs.  
8.7 Power-Down  
The standard EVM is used for this test by completely removing the shorting block on jumper JPD. A high-speed,  
50-Ω pulse generator is used to drive the PDx pin that toggles the output signal on or off depending upon the  
PDx pin voltage.  
8.8 Crosstalk, Gain Matching, and Phase Matching  
The standard EVM is used for these tests with both channels enabled. For gain and phase matching, the  
responses of both channels are measured on a network analyzer and the gain and phase values are compared.  
For crosstalk, a single channel is driven with a signal on the network analyzer when the other channel is  
measured.  
8.9 Output Measurement Reference Points  
The LMH2832 has two on-chip, 10-Ω output resistors on each channel. When matching the output to a 100-Ω  
load, the evaluation module (EVM) uses an external 40-Ω resistor on each output leg to complete the output  
matching. The inclusion of on-chip output resistors creates two potential reference points for measuring the  
output voltage. The first reference point is at the internal amplifier output (OUT_AMP), and the second reference  
point is at the externally-matched 100-Ω load (OUT_LOAD). The measurements in the Electrical Characteristics  
table and in the Typical Characteristics section are referred to the (OUT_AMP) reference point unless otherwise  
specified. The conversion between reference points is a straightforward correction of 3 dB for power and 6 dB for  
voltage, as shown in Equation 1 and Equation 2. The measurements are referenced to OUT_AMP when not  
specified.  
VOUT_LOAD = (VOUT_AMP – 6 dB)  
POUT_LOAD = (POUT_AMP – 3 dB)  
(1)  
(2)  
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9 Detailed Description  
9.1 Overview  
Each channel of the LMH2832 consists of an input attenuator block followed by a fully differential amplifier that  
has a gain of 30 dB. The attenuator has a range of 0 dB to –39 dB in 1-dB steps that is controlled by an SPI  
interface. The two channels can be controlled independently using the digital interface including power-down and  
bias settings. A separate analog power-down pin (PDA, PDB) is also included for each channel so that the  
device can bet set to a low-power state without waiting for a serial write to a register. The internal registers also  
include a power-on-reset (POR) that ensures the device starts in a known state after the power is reset.  
9.2 Functional Block Diagram  
1-dB Attenuator Steps:  
0 dB to -39 dB  
INPA  
OUTPA  
OUTMA  
FDA  
G = 30 dB  
150  
INMA  
PDA  
CS  
SCLK  
SDI  
Channel A Control Logic  
Channel B Control Logic  
SPI  
POR  
SDO  
PDB  
INMB  
OUTMB  
OUTPB  
FDA  
G = 30 dB  
150 ꢀ  
INPB  
1-dB Attenuator Steps:  
0 dB to -39 dB  
9.3 Feature Description  
9.3.1 Analog Input Characteristics  
The LMH2832 is a dual-channel device with two identical channels (A and B) that each have differential input  
pins (INP and INM) that denote the positive and negative inputs, respectively. The inputs are expected to be ac-  
coupled only, typically through a transformer or capacitor. The amplifier self-biases the input common-mode to  
mid-supply for the maximum input voltage range. The inputs of the LMH2832 can only be driven differentially. For  
single-ended input source applications, use a balun or fully differential amplifier (such as the LMH3401 or  
LMH5401) that can convert single-ended to differential signals before the LMH2832.  
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Feature Description (continued)  
At maximum gain, the digital attenuator is set to 0 dB of attenuation, causing the input signal to be much larger  
than the output signal and forcing the maximum output voltage swing to be limited by the outputs of the device.  
However at minimum gain, the maximum voltage swing is limited by the inputs of the device because the  
attenuator causes the output voltage to be 9 dB lower than the input voltage. In minimum gain, the input voltage  
limits against the electrostatic discharge (ESD) devices before the output reaches the maximum swing limits. For  
linear operation, the input voltage must be kept within the maximum input voltage ratings described in the  
Electrical Characteristics table.  
The input impedance of the LMH2832 is set by internal termination resistors to a nominal value of 150 Ω,  
differential. Process variations result in a range of values, as described in the Electrical Characteristics table. The  
input impedance is also affected by device parasitic effects at higher frequencies that cause the impedance to  
shift away from the nominal value.  
9.3.2 Analog Output Characteristics  
The LMH2832 has series, 10-Ω, on-chip resistors on each output to provide isolation from board parasitics that  
can cause instability. When designing a filter following the LMH2832, the filter source impedance calculation  
must include the two 10-Ω, on-chip resistors. Table 2 shows the calculated external source impedance values  
required for various matched filter loads.  
Table 2. Output Resistor Values for Matched Loads  
MATCHED FILTER IMPEDANCE (Ω)  
EXTERNAL SERIES RESISTOR PER OUTPUT (Ω)  
100  
150  
200  
300  
80  
130  
180  
280  
9.3.3 Driving Low Insertion-Loss Filters  
When driving high-speed ADCs, a filter is commonly driven with a matched impedance to the ADC. This  
impedance is matched by the amplifier by setting the combination of the output resistors to the same impedance  
as the ADC inputs. Impedance matching is often done to minimize any transmission reflections caused by the  
physical signal path. The drawback to using a matched impedance is that a voltage swing is required from the  
amplifier outputs that is twice the desired ADC input voltage swing, which can cause output voltage limitation  
issues.  
To avoid using a matched impedance, a low insertion loss filter can be driven where there is little to no  
resistance added at the amplifier outputs. The amplifier outputs then only must swing to the value of the ADC  
full-scale input voltage, thus eliminating most of the potential amplifier output headroom issues. The requirements  
of this technique are that the amplifier must be able to provide enough current to the load of the ADC and that  
the path between the amplifier outputs and ADC inputs must be minimized to prevent any reflections.  
9.3.4 Input Impedance Matching  
The LMH2832 has a differential input impedance of 150 Ω that can be easily matched to single-ended, 50-Ω or  
75-Ω systems using baluns. For a single-ended, 50-Ω input, a 1:3-Ω ratio balun can be used to create a 150-Ω  
differential source impedance to the device with a balun gain of 4.8 dB. For a single-ended, 75-Ω input, a 1:2-Ω  
ratio balun creates a 150-Ω differential source impedance to the device with a voltage gain of 3 dB.  
9.3.5 Power-On Reset (POR)  
The LMH2832 has a built-in, power-on-reset (POR) that sets the device registers to their default state (see the  
Register Maps section) on power-up. Note that the LMH2832 register information is lost when power is removed.  
When power is reapplied, the POR ensures that the device enters a default state. Power glitches (of sufficient  
duration) can also initiate the POR and return the device to a default state.  
20  
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9.4 Device Functional Modes  
9.4.1 Power-Down (PD)  
The device supports power-down control using an external power-down (PDx) pin or by writing a logic high to bit  
6 of SPI register 2h (see the Register Maps section). The external PDx pins are active high; when left floating,  
the device defaults to an on condition resulting from the internal pulldown resistors that cause a logic low on the  
PDx pins. The device PDx thresholds are noted in the Electrical Characteristics table. The device consumes  
approximately 7 mA in power-down mode. Note that the SPI register contents are preserved in power-down  
mode.  
9.4.2 Gain Control  
The LMH2832 gain can be controlled from 30-dB gain (0-dB attenuation) to –9-dB gain in 1-dB steps by digitally  
programming the SPI register 2h; see the Register Maps section for more details.  
9.5 Programming  
9.5.1 Details of the Serial Interface  
The LMH2832 has a set of internal registers that can be accessed by the serial interface formed by the CS  
(serial interface enable), SCLK (serial interface clock), SDI (serial interface input data), and SDO (serial interface  
read-back data) pins. Serially shifting bits into the device is enabled when CS is low. SDI serial data are latched  
at every SCLK rising edge when CS is active (low). The serial data are loaded into the register at every 16th  
SCLK rising edge when CS is low. When the word length exceeds a multiple of 16 bits, the excess bits are  
ignored. Data can be loaded in multiples of 16-bit words within a single active CS pulse. The first eight bits form  
the register address and the remaining eight bits are the register data. The interface can function with SCLK  
frequencies from 25 MHz down to very low speeds (of a few hertz) and also with a non-50% SCLK duty cycle. A  
summary of the LMH2832 SPI protocol is:  
1. SPI-1.1 interface  
2. Independent channel A, B attenuation programming (6-bit gain control)  
3. SPI register contents are preserved in power-down mode  
4. SPI-controlled power modes (3-bit control for eight options to step down the power)  
5. Powered for the main 5-V power supply  
6. 1.8-V logic  
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Programming (continued)  
9.5.2 Timing Diagrams  
Figure 45 and Figure 46 show timing diagrams for the SPI write and read bus cycles, respectively. Figure 47  
shows an example timing diagram for a streaming write cycle and Figure 48 shows an example timing diagram  
for a streaming read cycle. Figure 49, Figure 50, Figure 51, and Figure 52 illustrate timing diagrams and  
requirements for the clock, data input, data output, and chip select, respectively. See the Timing Requirements:  
SPI table for SPI timing requirements.  
CS  
1
2
3
4
5
6
7
8
9
10 11  
12 13 14 15 16  
SCLK  
SDI  
A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0  
SDO  
Figure 45. SPI Write Bus Cycle Timing Diagram  
CS  
1
2
3
4
5
6
7
8
9
10 11  
12 13 14 15 16  
SCLK  
SDI  
A6 A5 A4 A3 A2 A1 A0  
D7 D6 D5 D4 D3 D2 D1 D0  
SDO  
Figure 46. SPI Read Bus Cycle Timing Diagram  
CS  
1
2
3
4
5
6
7
8
9
10 11  
12 13 14 15 16 17 18 19 20 21 22 23 24  
SCLK  
Addr N  
Addr N+1  
SDI  
A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0  
SDO  
Figure 47. SPI Streaming Write Example Timing Diagram  
CS  
1
2
3
4
5
6
7
8
9
10 11  
12 13 14 15 16 17 18 19 20 21 22 23 24  
SCLK  
Addr N+1  
Addr N  
A6 A5 A4 A3 A2 A1 A0  
SDI  
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0  
SDO  
Figure 48. SPI Streaming Read Example Timing Diagram  
tPH  
tPL  
SCLK  
tPL  
Figure 49. SPI Clock Timing Diagram  
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Programming (continued)  
SCLK  
tSU  
tH  
SDI  
Figure 50. SPI Data Input Timing Diagram  
CS  
CS  
CS  
tODZ  
tOD  
tODZ  
SDOen  
SDOen  
SDO  
a) Need Title  
b) Need Title  
c) Need Title  
Figure 51. SPI Data Output Timing Diagrams  
SCLK  
tCSS  
tCSH  
tIAG  
CS  
CS  
a) Need Title  
b) Need Title  
Figure 52. SPI Chip Select Timing Diagrams  
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9.6 Register Maps  
Table 3 shows the SPI registers for the LMH2832.  
Table 3. SPI Register Map  
REGISTER DATA  
ADDRESS  
(A[6:0])  
DEFAULT  
(Hex)  
R/W  
R
REGISTER NAME  
Revision ID  
7
1
0
6
5
1
1
4
1
3
0
0
2
1
1
1
0
1
0
B3  
23  
00  
00  
20  
14  
20  
14  
00  
0
0
1
R
Product ID  
0
0
0
1
2
R/W  
R/W  
R/W  
R/W  
R/W  
R/W  
R
SW reset  
Reserved  
Reserved  
Reset B  
PD B  
Reserved  
Reserved  
Reset A  
PD A  
3
Power-down  
4
Channel A RW0, bias control  
Channel A RW1, attenuator control  
Channel B RW0, bias control  
Channel B RW1, attenuator control  
Reserved  
Channel A RW0  
Channel A RW1  
Channel B RW0  
Channel B RW1  
5
6
7
8-127  
0
0
0
0
0
0
0
0
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9.6.1 Register Descriptions  
Exercising the SW reset function returns all registers to the default values of the respective channel.  
9.6.1.1 SW Reset Register (address = 2)  
Figure 53. SW Reset Register  
7
6
5
4
3
2
1
0
Reserved  
R-0h  
Reset B  
R/W-0h  
Reserved  
R-0h  
Reset A  
R/W-0h  
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset  
Table 4. SW Reset Register Field Descriptions  
Bit  
7-5  
4
Field  
Type  
R
Reset  
0h  
Description  
Reserved  
Reset B  
Reserved.  
R/W  
0h  
This bit is a self-clearing bit.  
0 = No action  
1 = Reset  
3-1  
0
Reserved  
Reset A  
R
0h  
0h  
Reserved.  
R/W  
This bit is a self-clearing bit.  
0 = No action  
1 = Reset  
9.6.2 Power-Down Control Register (address = 3)  
Figure 54. Power-Down Control Register  
7
6
5
4
3
2
1
0
Reserved  
R-0h  
PD B  
R/W-0h  
Reserved  
R-0h  
PD A  
R/W-0h  
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset  
Table 5. Power-Down Control Register Field Descriptions  
Bit  
7-5  
4
Field  
Type  
R
Reset  
0h  
Description  
Reserved  
PD B  
Reserved.  
R/W  
0h  
0 = Active  
1 = PD  
3-1  
0
Reserved  
PD A  
R
0h  
0h  
Reserved.  
R/W  
0 = Active  
1 = PD  
9.6.3 Channel A RW0 Register (address = 4)  
Figure 55. Channel A RW0 Register  
7
6
5
4
3
2
1
0
Channel A RW0  
R/W-0h  
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset  
Table 6. Channel A RW0 Register Field Descriptions  
Bit  
Field  
Type  
Reset  
Description  
7-0  
Channel A RW0  
R/W  
0h  
These bits drive the output CHA_RW0[7:0] and are reset by a  
device reset or Reset A. Table 10 lists controls for this register.  
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9.6.4 Channel A RW1 Register (address = 5)  
Figure 56. Channel A RW1 Register  
7
6
5
4
3
2
1
0
Channel A RW1  
R/W-0h  
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset  
Table 7. Channel A RW1 Register Field Descriptions  
Bit  
Field  
Type  
Reset  
Description  
7-0  
Channel A RW1  
R/W  
0h  
These bits drive the output CHA_RW1[7:0] and are reset by a  
device reset or Reset A. Table 11 lists controls for this register.  
9.6.5 Channel B RW0 Register (address = 6)  
Figure 57. Channel B RW0 Register  
7
6
5
4
3
2
1
0
Channel B RW0  
R/W-0h  
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset  
Table 8. Channel B RW0 Register Field Descriptions  
Bit  
Field  
Type  
Reset  
Description  
7-0  
Channel B RW0  
R/W  
0h  
These bits drive the output CHB_RW0[7:0] and are reset by a  
device reset or Reset B. Table 10 lists controls for this register.  
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9.6.6 Channel B RW1 Register (address = 7)  
Figure 58. Channel B RW1 Register  
7
6
5
4
3
2
1
0
Channel B RW1  
R/W-0h  
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset  
Table 9. Channel B RW1 Register Field Descriptions  
Bit  
Field  
Type  
Reset  
Description  
7-0  
Channel B RW1  
R/W  
0h  
These bits drive the output CHB_RW1[7:0] and are reset by a  
device reset or Reset B. Table 11 lists controls for this register.  
Table 10. Bias Control Register Bit Settings (Channels A, B)(1)  
7
0
0
0
0
0
0
0
0
1
6
0
0
0
0
0
0
0
1
X
5
0
0
0
0
0
0
1
X
X
4
0
0
0
0
0
1
X
X
X
3
0
0
0
0
1
X
X
X
X
2
0
1
0
0
0
0
0
1
0
1
X
X
X
X
X
X
X
1
X
X
X
X
X
X
X
X
X
X
X
(1) Default value: 001xxxxx. Highest power: 1xxxxxxx. Lower power: 00000000.  
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Table 11. Attenuator Control Register Bit Settings (Channels A, B)(1)  
7
6
5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
Reserved, always read 0  
(1) Default attenuation setting: xx001011. Maximum attenuation (lowest gain setting): xx100111. Minimum attenuation (highest gain setting):  
xx000000.  
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10 Application and Implementation  
NOTE  
Information in the following applications sections is not part of the TI component  
specification, and TI does not warrant its accuracy or completeness. TI’s customers are  
responsible for determining suitability of components for their purposes. Customers should  
validate and test their design implementation to confirm system functionality.  
10.1 Application Information  
The LMH2832 is designed as a general-purpose, analog-to-digital converter (ADC) driver that also meets the  
performance requirements for DOCSIS 3.X upstream CMTS solutions. This section describes various  
requirements and considerations for using the LMH2832 and also some design examples.  
10.1.1 Driving ADCs  
When the amplifier is driving an ADC, the key points to consider for implementation are the signal-to-noise ratio  
(SNR), spurious-free dynamic range (SFDR), and ADC input considerations, as described in this section.  
A typical application of the LMH2832 involves driving a wideband, 14-bit ADC (such as the ADS54J40), as  
shown in Figure 59. The LMH2832 can drive the full Nyquist bandwidth of ADCs with sampling rates up to  
900 MSPS. If the front-end bandwidth of the ADC is more than 450 MHz, then use a simple noise filter to  
improve SNR. Otherwise, the ADC can be connected directly to the amplifier output pins with appropriate  
matching resistors to limit the full-scale input of the ADC. Note that the LMH2832 inputs must be driven  
differentially using a balun or fully differential amplifiers (FDAs). For dc-coupled applications, an FDA (such as  
the LMH3401 or LMH5401) that can convert a single-ended input to a differential output with low distortion is  
preferred.  
VS+ = 5V  
10  
RO  
ZS = 50-Ω  
OUTPx  
OUTMx  
1:3  
INPx  
INMx  
+
-
½ LMH2832  
ADC  
OUT_AMP  
LPF  
10 ꢀ  
RO  
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SPI  
GND  
Figure 59. ADC Driver with a 50-Ω Source  
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Application Information (continued)  
10.1.1.1 SNR Considerations  
When using the LMH2832 with a filter, the signal-to-noise ratio (SNR) of the amplifier and filter can be calculated  
from the amplitude of the signal and the bandwidth of the filter. The noise from the amplifier is band-limited by  
the filter with the equivalent brick-wall filter bandwidth. The amplifier and filter noise can be calculated using  
Equation 3:  
V2  
VO  
O
SNRAMP+FILTER = 10 × log  
= 20 × log  
e2  
eFILTEROUT  
FILTEROUT  
where:  
eFILTEROUT = eNAMPOUT ENB  
eNAMPOUT = the output noise density of the LMH2832 (50.4 nV/Hz) at AV = 30 dB  
ENB = the brick-wall equivalent noise bandwidth of the filter  
VO = the amplifier output signal  
(3)  
For example, with a first-order (N = 1) band-pass or low-pass filter with a 1000-MHz cutoff, ENB is 1.57 • f–3dB  
=
1.57 • 1000 MHz = 1570 MHz. For second-order (N = 2) filters, ENB is 1.22 • f–3dB. When the filter order  
increases, ENB approaches f–3dB (N = 3 ENB = 1.15 • f–3dB; N = 4 ENB = 1.13 • f–3dB). Both VO and  
eFILTEROUT are in RMS voltages. For example, with a 2-VPP (0.707 VRMS) output signal and a 300-MHz, first-order,  
low-pass filter, the SNR of the amplifier and filter is 56 dB with eFILTEROUT = 50.4 nV/Hz • 471 MHz = 1.09  
mVRMS  
.
The SNR of the amplifier, filter, and ADC sum in RMS fashion, as shown in Equation 4 (SNR values in dB):  
-SNRAMP+FILTER  
-SNRADC  
10  
10  
SNRSYSTEM = -20 × log  
10  
+ 10  
(4)  
This formula shows that if the SNR of the amplifier and filter equals the SNR of the ADC, then the combined  
SNR is 3 dB lower (worse). Thus, for minimal degradation (< 1 dB) on the ADC SNR, the SNR of the amplifier  
and filter must be 10 dB greater than the ADC SNR. The combined SNR calculated in this manner is usually  
accurate to within ±1 dB of the actual implementation.  
10.1.1.2 SFDR Considerations  
The SFDR of the amplifier is usually set by the second- or third-order harmonic distortion for single-tone inputs,  
and by the second-order or third-order intermodulation distortion for two-tone inputs. Harmonics and second-  
order intermodulation distortion can be filtered to some degree, but third-order intermodulation spurs cannot be  
filtered. The ADC generates the same distortion products as the amplifier, but also generates additional spurs  
(not harmonically related to the input signal) as a result of sampling and clock feed through.  
When the spurs from the amplifier and filter are known, each individual spur can be directly added to the same  
spur from the ADC, as shown in Equation 5, to estimate the combined spur (spur amplitudes in dBc):  
-HDxAMP+FILTER  
-HDxADC  
20  
20  
HDxSYSTEM = -20 × log  
10  
+ 10  
(5)  
This calculation assumes that the spurs are in phase, but usually provides a good estimate of the final combined  
distortion.  
For example, if the spur of the amplifier and filter equals the spur of the ADC, then the combined spur is 6 dB  
higher. To minimize the amplifier contribution (< 1 dB) to the overall system distortion, the spur from the amplifier  
and filter must be approximately 15 dB lower in amplitude than that of the converter. The combined spur  
calculated in this manner is usually accurate to within ±6 dB of the actual implementation; however, higher  
variations can be detected as a result of phase shift in the filter, especially in second-order harmonic  
performance.  
30  
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LMH2832  
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Application Information (continued)  
This worst-case spur calculation assumes that the amplifier and filter spur of interest is in phase with the  
corresponding spur in the ADC, such that the two spur amplitudes can be added linearly. There are two phase-  
shift mechanisms that cause the measured distortion performance of the amplifier-ADC chain to deviate from the  
expected performance calculated using Equation 5; one mechanism is the common-mode phase shift and the  
other is the differential phase shift.  
Common-mode phase shift is the phase shift detected equally in both branches of the differential signal path  
including the filter. Common-mode phase shift nullifies the basic assumption that the amplifier, filter, and ADC  
spur sources are in phase. This phase shift can lead to better performance than predicted when the spurs  
become phase shifted, and there is the potential for cancellation when the phase shift reaches 180°. However,  
there is a significant challenge in designing an amplifier-ADC interface circuit to take advantage of a common-  
mode phase shift for cancellation: the phase characteristics of the ADC spur sources are unknown, thus the  
necessary phase shift in the filter and signal path for cancellation is also unknown.  
Differential phase shift is the difference in the phase response between the two branches of the differential filter  
signal path. Differential phase shift in the filter is a result of mismatched components caused by nominal  
tolerances and can severely degrade the even harmonic distortion of the amplifier-ADC chain. This effect has the  
same result as mismatched path lengths for the two differential traces, and causes more phase shift in one path  
than the other. Ideally, the phase responses over frequency through the two sides of a differential signal path are  
identical, such that even harmonics remain optimally out of phase and cancel when the signal is taken  
differentially. However, if one side has more phase shift than the other, then the even harmonic cancellation is  
not as effective.  
Single-order, resistor-capacitor (RC) filters cause very little differential phase shift with nominal tolerances of 5%  
or less, but higher-order, inductor-capacitor (LC) filters are very sensitive to component mismatch. For instance,  
a third-order Butterworth band-pass filter with a 100-MHz center frequency and a 20-MHz bandwidth displays as  
much as 20° of differential phase imbalance in a SPICE Monte Carlo analysis with 2% component tolerances.  
Therefore, although a prototype may work, production variance is unacceptable. For ac-coupled or dc-coupled  
applications where a transformer or balun cannot be used, using first- or second-order filters is recommended to  
minimize the effect of differential phase shift.  
10.1.1.3 ADC Input Common-Mode Voltage Considerations (AC-Coupled Input)  
When interfacing to an ADC, the input common-mode voltage range of the ADC must be taken into account for  
proper operation. In an ac-coupled application between the amplifier and the ADC, the input common-mode  
voltage bias of the ADC can be accomplished in different ways. Some ADCs use internal bias networks such that  
the analog inputs are automatically biased to the required input common-mode voltage if the inputs are ac-  
coupled with capacitors (or if the filter between the amplifier and ADC is a band-pass filter). Other ADCs supply  
the required input common-mode voltage from a reference voltage output pin (often termed CM or VCM). With  
these ADCs, the ac-coupled input signal can be re-biased to the input common-mode voltage by connecting  
resistors from each input to the CM output of the ADC, as shown in Figure 60. AC coupling provides dc common-  
mode isolation between the amplifier and the ADC; thus, the output common-mode voltage of the amplifier is a  
don’t care for the ADC.  
RO  
RCM  
AIN+  
Amp  
ADC  
CM  
AIN-  
RCM  
RO  
Figure 60. Biasing AC-Coupled ADC Inputs Using the ADC CM Output  
Copyright © 2016, Texas Instruments Incorporated  
31  
 
LMH2832  
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Application Information (continued)  
10.1.1.4 ADC Input Common-Mode Voltage Considerations (DC-Coupled Input)  
The LMH2832 is designed to primarily be used in ac-coupled applications only. However, the LMH2832 can be  
dc-coupled if certain strict conditions are met. The LMH2832 has an internal common-mode bias equal to the  
mid-supply voltage, so any dc coupling on the input or output must have a common-mode voltage that is also set  
to mid-supply. To dc couple to an ADC input, the mid-supply voltage of the LMH2832 must be centered around  
the ADC input common-mode. This common-mode matching can be accomplished by shifting the supplies to  
center the mid-supply voltage around the ADC input common-mode voltage. However, shifting the supplies also  
changes the ground reference for the digital inputs, which then likely requires a voltage-shifted interface as well.  
The LMH2832 is not recommended to be operated as dc-coupled unless absolutely necessary.  
10.2 Typical Applications  
10.2.1 DOCSIS 3.X Driver  
The LMH2832 is designed to perform best when driving differential input ADCs in high-speed applications.  
Figure 61 shows an example diagram of the LMH2832 driving an ADC with a fifth-order, low-pass filter for a 75-Ω  
impedance, data over cable service interface specification (DOCSIS) 3.X upstream receiver return path  
application. The primary interface between the amplifier and the ADC is usually an antialiasing filter to suppress  
high-frequency harmonics that otherwise alias back into the ADC FFT spectrum. Filters range from single-order  
real RC poles to higher-order, resistor-inductor-capacitor (RLC) filters, depending on the application  
requirements. Series output resistors (RO) help isolate the amplifier from any capacitive load presented by the  
filter, and can also be used to create a matched impedance to drive transmission lines.  
VS+ = 5V  
0.1 µF  
0.1 µF  
24 nH  
5.5 pF  
24 nH  
82 nH  
5.5 pF  
82 nH  
24 nH  
10  
64.9 ꢀ  
64.9 ꢀ  
5.1 ꢀ  
5.1 ꢀ  
0.1 µF  
0.1 µF  
ZS = 75-Ω  
1:2 O  
INPx  
INMx  
OUTPx  
OUTMx  
100 ꢀ  
100 ꢀ  
+
-
½ LMH2832  
½ ADS54J40  
VOCM  
OUT_AMP  
10 ꢀ  
24 nH  
SPI  
Copyright © 2016, Texas Instruments Incorporated  
GND  
Figure 61. DOCSIS 3.X Driver with the ADS54J40 and a 300-MHz, 4th-Order, Butterworth, Low-Pass Filter  
10.2.1.1 Design Requirements  
Table 12 shows example design requirements for the LMH2832 in an upstream receiver application.  
Table 12. Example Design Requirements  
SPECIFICATION  
Supply voltage  
DESIGN REQUIREMENTS  
4.75 to 5.25 V  
Usable input frequency range  
System voltage gain and range  
Source impedance  
300 MHz  
33-dB voltage gain with 30-dB range  
75 Ω, single-ended  
> 50 dBFS  
Signal path SNR at 175 MHz (measured at ADC)  
32  
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10.2.1.2 Detailed Design Procedure  
To begin the design process, make sure that none of the following design parameters exceed the limits listed in  
the Electrical Characteristics table, such as:  
Supply voltage  
Temperature range  
Input voltage range across gain  
Output current requirements  
Digital I/O voltages and currents  
10.2.1.2.1 Source Resistance Matching  
Standard DOCSIS systems use a characteristic single-ended impedance of 75 Ω that must be properly matched  
to the 150-Ω differential impedance of the LMH2832. The circuit in Figure 61 uses a transformer with a 1:2-Ω  
ratio to convert the signal from single-ended to differential, and also to match the differential impedance. The  
transformer also adds a signal gain of approximately 3 dB to the system with some insertion loss depending on  
the chosen transformer.  
10.2.1.2.2 Output Impedance Matching  
For the circuit in Figure 61, the output impedance is matched to a 150-Ω characteristic impedance filter to  
maximize the performance of the LMH2832. On the amplifier output side, the output impedance is matched to  
150 Ω by including a 65-Ω series resistor on each output. Combined with the internal 10-Ω resistors on each  
output, the total differential impedance becomes 150 Ω. The ADS54J40 has an input impedance of  
approximately 600 Ω that is reduced to 150 Ω by using two 5-Ω series input resistors in parallel with two 100-Ω  
series resistors. The 5-Ω series resistors are included to isolate the input capacitance of the ADC so that the  
response of the filter is not affected. With both the amplifier and ADC impedances matched, any transmission  
line effects of the connection are minimized.  
If the ADC is physically located close enough to the amplifier, a matched impedance may not be needed; see  
Driving Low Insertion-Loss Filters section for more information on driving non-matched filters.  
10.2.1.2.3 Voltage Headroom Considerations  
Because of the series resistors included on both the amplifier outputs and ADC inputs, the amplifier must drive a  
voltage that is significantly higher than the ADC full-scale input. For the circuit in Figure 61, the ADS54J40 full-  
scale input voltage is 1.9 VPP, so the required voltage at the amplifier output pins is 3.6 VPP. This voltage is less  
than the specified output voltage of 5 VPP for the LMH2832, thus system performance is not limited. If the  
required output voltage is higher than what the amplifier can support, then the matched resistance value can be  
reduced. However, this reduction can have performance implications because more current output is required  
from the amplifier.  
The input voltage swing can be larger than the output voltage swing because the LMH2832 can operate as an  
attenuator. To maintain the full-scale voltage of the ADS54J40 input in this application, the amplifier cannot  
attenuate more than 1 dB from input to output; otherwise, the maximum input voltage swing is exceeded. If the  
amplifier must be operated with more attenuation, then the output voltage must be reduced.  
Copyright © 2016, Texas Instruments Incorporated  
33  
LMH2832  
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www.ti.com.cn  
10.2.1.3 Application Curve  
-40  
-50  
-60  
-70  
-80  
-90  
Channel A to B  
Channel B to A  
-100  
-110  
0
50 100 150 200 250 300 350 400 450 500  
Frequency (MHz)  
D037  
Figure 62. Amplifier Dual Channel Isolation Presented to ADC Interface  
10.2.2 IQ Receiver  
The LMH2832 is a dual-channel device; therefore, the device has excellent gain and phase matching between  
channels A and B. This matching makes the LMH2832 an excellent choice for systems that require two matched  
channels (such as an IQ demodulation receiver), as shown in Figure 63. For an IQ system, both the gain and  
phase must match for the real and imaginary channel. When using two single-channel amplifiers, the matching  
characteristics are subject to process lot and packaging variations for two individual devices, and there is often  
no way to make sure that the amplifiers match without testing each amplifier. However, the dual-channel  
architecture of the LMH2832 allows for much tighter gain and phase matching with minimal crosstalk effects. For  
more matching information, see the Electrical Characteristics table.  
I Channel  
RF IN  
LPF  
LMH2832  
ADS54J60  
LPF  
Q Channel  
Copyright © 2016, Texas Instruments Incorporated  
Figure 63. IQ Receiver Block Diagram  
34  
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LMH2832  
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ZHCSF77A JULY 2016REVISED JULY 2016  
10.3 Do's and Don'ts  
10.3.1 Do:  
Include a thermal analysis at the beginning of the project  
Use well-terminated transmission lines for all signals  
Maintain symmetrical input and output trace layouts  
Use solid metal layers for the power supplies  
Keep signal lines as straight as possible  
10.3.2 Don't:  
Use a lower power-supply voltage than necessary  
Forget about the common-mode response of filters and transmission lines  
Rout digital line traces close to the analog signals and supply line traces  
11 Power Supply Recommendations  
The LMH2832 is designed to be used with a single supply with a range of 4.75 V to 5.25 V. The ideal supply  
voltage is a 5.0-V total single-ended supply. If the supply is reduced to the minimum voltage, then the maximum  
input and output voltage range is reduced by 0.25 V.  
11.1 Split Supplies  
Ideally, the LMH2832 uses a single-ended, 5-V supply, but the device can be operated on a split supply if  
necessary. However, the digital logic is referenced to the GND pins, meaning that the logic reference shifts with  
the GND supply if connected to a negative voltage and must be accounted for in the logic connections. In  
general, the LMH2832 is not suggested to be operated with a split-supply configuration.  
11.2 Supply Decoupling  
Power-supply decoupling is critical to high-frequency performance. Onboard bypass capacitors are used on the  
LMH2832EVM; however, the most important component of the supply bypassing is provided by the printed circuit  
board (PCB). As illustrated in Figure 64, there are multiple vias connecting the LMH2832 power planes to the  
power-supply traces. These vias connect the internal power planes to the LMH2832. Both VCC and GND must be  
connected to the internal power planes with several square centimeters of continuous plane in the immediate  
vicinity of the amplifier. The capacitance between these power planes provides the bulk of the high-frequency  
bypassing for the LMH2832.  
Copyright © 2016, Texas Instruments Incorporated  
35  
LMH2832  
ZHCSF77A JULY 2016REVISED JULY 2016  
www.ti.com.cn  
12 Layout  
12.1 Layout Guidelines  
With a small bandwidth greater than 1 GHz, layout for the LMH2832 is critical and nothing can be neglected. In  
order to simplify board design, the LMH2832 has on-chip resistors that reduce the affect of off-chip capacitance.  
For this reason, make sure that the ground layer below the LMH2832 is not cut. The recommendation to not cut  
the ground plane under the amplifier input and output pins is different than many other high-speed amplifiers, but  
the reason is that parasitic inductance is more harmful to the LMH2832 performance than parasitic capacitance.  
By leaving the ground layer under the device intact, parasitic inductance of the output and power traces is  
minimized. The DUT portion of the evaluation board layout is shown in Figure 64.  
The EVM uses long-edge capacitors for the decoupling capacitors, which reduces series resistance and  
increases the resonant frequency. Vias are also placed to the power planes before the bypass capacitors.  
Although not evident in the top layer, two vias are used at the capacitor in addition to the two vias underneath the  
device.  
The output-matching resistors are 0402 size and are placed very close to the amplifier output pins, which  
reduces both parasitic inductance and capacitance. The use of 0603 output-matching resistors produces a  
measurable decrease in bandwidth.  
When the signal is on a 50-Ω or 75-Ω controlled impedance transmission line, the layout then becomes much  
less critical. The transition from the 50-Ω or 75-Ω transmission line to the amplifier pins is the most critical area.  
12.2 Layout Example  
Figure 64. Layout Example  
36  
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13 器件和文档支持  
13.1 器件支持  
13.1.1 器件命名规则  
Legend:  
= Pin 1 Designator  
LMH2832  
IRHA  
LMH2832 = Device Name  
TI = Texas Instruments  
TI YMS  
LLLL  
YM = Year Month Date Code  
S = Assembly Site Code  
LLLL = Assembly Lot Code  
65. 器件标识信息  
13.2 文档支持  
13.2.1 相关文档ꢀ  
相关文档请参见以下部分:  
数据表《ADS54J40 双通道 14 1.0GSPS 模数转换器》(文献编号:SBAS714)  
数据表《LMH3401 7GHz 超宽带、固定增益、全差分放大器》(文献编号:SBOS695)  
数据表《LMH5401 8GHz 低噪声、低功耗、全差分放大器》(文献编号:SBOS710)  
数据表《LMH6521 高性能双路 DVGA(文献编号:SNOSB47)  
数据表《LMH3404 双通道 7GHz 低噪声、低功耗全差分放大器》(文献编号:SBOS739)  
数据表《LMH3402 双路可选增益 7GHz 低噪声、低功耗全差分放大器》(文献编号:SBOS744)  
用户指南《LMH2832EVM-50 评估模块》(文献编号:SLOU454)  
用户指南《LMH2832EVM-75 评估模块》(文献编号:SLOU438)  
LMH2832 TINA-TI 参考设计》(文献编号:SBOMA21)  
LMH2832 TINA-TI Spice 模型》(文献编号:SBOMA22)  
13.3 接收文档更新通知  
如需接收文档更新通知,请访问 www.ti.com.cn 网站上的器件产品文件夹。点击右上角的提醒我 (Alert me) 注册  
后,即可每周定期收到已更改的产品信息。有关更改的详细信息,请查阅已修订文档中包含的修订历史记录。  
13.4 社区资源  
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective  
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of  
Use.  
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration  
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help  
solve problems with fellow engineers.  
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and  
contact information for technical support.  
13.5 商标  
E2E is a trademark of Texas Instruments.  
Keysight Technologies is a trademark of Keysight Technologies.  
SPI is a trademark of Motorola Mobility LLC.  
All other trademarks are the property of their respective owners.  
版权 © 2016, Texas Instruments Incorporated  
37  
LMH2832  
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www.ti.com.cn  
13.6 静电放电警告  
ESD 可能会损坏该集成电路。德州仪器 (TI) 建议通过适当的预防措施处理所有集成电路。如果不遵守正确的处理措施和安装程序 , 可  
能会损坏集成电路。  
ESD 的损坏小至导致微小的性能降级 , 大至整个器件故障。 精密的集成电路可能更容易受到损坏 , 这是因为非常细微的参数更改都可  
能会导致器件与其发布的规格不相符。  
13.7 Glossary  
SLYZ022 TI Glossary.  
This glossary lists and explains terms, acronyms, and definitions.  
14 机械、封装和可订购信息  
以下页中包括机械、封装和可订购信息。这些信息是针对指定器件可提供的最新数据。这些数据会在无通知且不对  
本文档进行修订的情况下发生改变。欲获得该数据表的浏览器版本,请查阅左侧的导航栏。  
38  
版权 © 2016, Texas Instruments Incorporated  
PACKAGE OPTION ADDENDUM  
www.ti.com  
10-Dec-2020  
PACKAGING INFORMATION  
Orderable Device  
Status Package Type Package Pins Package  
Eco Plan  
Lead finish/  
Ball material  
MSL Peak Temp  
Op Temp (°C)  
Device Marking  
Samples  
Drawing  
Qty  
(1)  
(2)  
(3)  
(4/5)  
(6)  
LMH2832IRHAR  
LMH2832IRHAT  
ACTIVE  
VQFN  
VQFN  
RHA  
40  
40  
2500 RoHS & Green  
250 RoHS & Green  
NIPDAU  
Level-3-260C-168 HR  
Level-3-260C-168 HR  
-40 to 85  
-40 to 85  
LMH2832  
IRHA  
ACTIVE  
RHA  
NIPDAU  
LMH2832  
IRHA  
(1) The marketing status values are defined as follows:  
ACTIVE: Product device recommended for new designs.  
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.  
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.  
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.  
OBSOLETE: TI has discontinued the production of the device.  
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance  
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may  
reference these types of products as "Pb-Free".  
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.  
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based  
flame retardants must also meet the <=1000ppm threshold requirement.  
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.  
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.  
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation  
of the previous line and the two combined represent the entire Device Marking for that device.  
(6)  
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two  
lines if the finish value exceeds the maximum column width.  
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information  
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and  
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.  
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.  
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.  
Addendum-Page 1  
PACKAGE OPTION ADDENDUM  
www.ti.com  
10-Dec-2020  
Addendum-Page 2  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
22-Jul-2016  
TAPE AND REEL INFORMATION  
*All dimensions are nominal  
Device  
Package Package Pins  
Type Drawing  
SPQ  
Reel  
Reel  
A0  
B0  
K0  
P1  
W
Pin1  
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant  
(mm) W1 (mm)  
LMH2832IRHAR  
LMH2832IRHAT  
VQFN  
VQFN  
RHA  
RHA  
40  
40  
2500  
250  
330.0  
180.0  
16.4  
16.4  
6.3  
6.3  
6.3  
6.3  
1.1  
1.1  
12.0  
12.0  
16.0  
16.0  
Q2  
Q2  
Pack Materials-Page 1  
PACKAGE MATERIALS INFORMATION  
www.ti.com  
22-Jul-2016  
*All dimensions are nominal  
Device  
Package Type Package Drawing Pins  
SPQ  
Length (mm) Width (mm) Height (mm)  
LMH2832IRHAR  
LMH2832IRHAT  
VQFN  
VQFN  
RHA  
RHA  
40  
40  
2500  
250  
367.0  
210.0  
367.0  
185.0  
38.0  
35.0  
Pack Materials-Page 2  
GENERIC PACKAGE VIEW  
RHA 40  
6 x 6, 0.5 mm pitch  
VQFN - 1 mm max height  
PLASTIC QUAD FLATPACK - NO LEAD  
This image is a representation of the package family, actual package may vary.  
Refer to the product data sheet for package details.  
4225870/A  
www.ti.com  
重要声明和免责声明  
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