MAX2055EUP+TD [MAXIM]
Baseband Circuit, BICMOS, PDSO20, 4.40 MM, ROHS COMPLIANT, MO-153AC, TSSOP-20;
| 型号： | MAX2055EUP+TD |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Baseband Circuit, BICMOS, PDSO20, 4.40 MM, ROHS COMPLIANT, MO-153AC, TSSOP-20 电信 信息通信管理 光电二极管 电信集成电路 |
| 文件： | 总13页 (文件大小：624K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2799; Rev 0; 4/03
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
MAX205
General Description
Features
The MAX2055 high-performance, digitally controlled,
variable-gain, differential analog-to-digital converter
(ADC) driver/amplifier (DVGA) is designed for use from
30MHz to 300MHz in base station receivers.
♦ 30MHz to 300MHz Frequency Range
♦ Single-Ended-to-Differential Conversion
♦ -3dB to +20dB Variable Gain
The device integrates a digitally controlled attenuator
and a high-linearity single-ended-to-differential output
amplifier, which can either eliminate an external trans-
former, or can improve the even-order distortion perfor-
mance of a transformer-coupled circuit, thus relaxing
the requirements of the anti-alias filter preceding an
ADC. Targeted for ADC driver applications to adjust
gain either dynamically or as a one-time channel gain
setting, the MAX2055 is ideal for applications requiring
high performance. The attenuator provides 23dB of
attenuation range with 0.2dB accuracy.
♦ 40dBm Output IP3 (at All Gain States and 70MHz)
♦ 2nd Harmonic -76dBc
♦ 3rd Harmonic -69dBc
♦ Noise Figure: 5.8dB at Maximum Gain
♦ Digitally Controlled Gain with 1dB Resolution and
0.2dB Accuracy
♦ Adjustable Bias Current
The MAX2055 is available in a thermally enhanced 20-
pin TSSOP-EP package and operates over the -40°C to
+85°C temperature range.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
Applications
MAX2055EUP-T
-40°C to +85°C
20 TSSOP-EP*
Cellular Base Stations
PHS/PAS Infrastructure
Receiver Gain Control
Broadband Systems
*EP = Exposed paddle.
Automatic Test Equipment
Terrestrial Links
Pin Configuration/
Functional Diagram
High-Performance ADC Drivers
TOP VIEW
20 GND
V
CC
1
19
18
17
16
15
14
13
12
11
ATTN
GND
RF_IN
2
3
OUT
GND
B4
MAX2055
I
4
SET
5
C
C
B3
ATTENUATION
B2
6
LOGIC
AMP
IN
CONTROL
L
E
B1
7
B0
C
I
8
BP
V
CC
9
BIAS
RF_OUT+
RF_OUT-
10
TSSOP
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
ABSOLUTE MAXIMUM RATINGS
All Pins to GND. .....................................-0.3V to +(V
+ 0.25V)
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +165°C
Lead Temperature (soldering, 10s) .................................+300°C
CC
Input Signal (RF_IN)............................…………………….20dBm
Output Power (RF_OUT)...................................................24dBm
Continuous Power Dissipation (T = +70°C)
A
20-Pin TSSOP (derate 21.7mW/°C above +70°C) ...........2.1W
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
MAX205
DC ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1; V
= +4.75V to +5.25V, GND = 0V. No input signals applied, and input and output ports are terminated with
CC
50Ω. R1 = 1.13kΩ, T = -40°C to +85°C. Typical values are at V
= +5V and T = +25°C, unless otherwise noted.) (Notes 1, 2)
A
CC
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SUPPLY
Supply Voltage
Supply Current
V
4.75
5.0
240
1.1
5.25
290
V
CC
I
mA
mA
CC
I
Current
I
SET
SET
CONTROL INPUTS
Control Bits
Parallel
5
Bits
V
Input Logic High
Input Logic Low
Input Leakage Current
2
0.6
V
-1.2
+1.2
µA
AC ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1; V
= +4.75V to +5.25V, GND = 0V, max gain (B0 = B1 = B2 = B3 = B4 = 0), R = 1.13kΩ, P = 5dBm,
CC
1
OUT
f
IN
= 70MHz, 50Ω system impedance. Typical values are at V
= +5V and T = +25°C, unless otherwise noted.) (Notes 1, 2)
CC A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MHz
dB
Frequency Range
Gain
f
30
300
R
G
19.9
0.06
0.7
Amplitude Unbalance
Phase Unbalance
Minimum Reverse Isolation
Noise Figure
(Note 3)
(Note 3)
dB
Degrees
dB
29
NF
5.8
dB
Output 1dB Compression Point
P
25.7
dBm
1dB
OIP2
OIP3
f + f , f = 70MHz, f = 71MHz, 5dBm/tone
at RF_OUT
1
2
1
2
2nd-Order Output Intercept Point
75
dBm
3rd-Order Output Intercept Point
2nd Harmonic
All gain conditions, 5dBm/tone at RF_OUT
40
-76
-69
23
1
dBm
dBc
dBc
dB
2f
3f
IN
IN
3rd Harmonic
RF Gain-Control Range
Gain-Control Resolution
Attenuation Absolute Accuracy
dB
Compared to the ideal expected attenuation
Between adjacent states
0.2
dB
+0.05/
-0.2
Attenuation Relative Accuracy
Gain Drift Over Temperature
dB
dB
T
= -40°C to +85°C
0.3
A
2
_______________________________________________________________________________________
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
AC ELECTRICAL CHARACTERISTICS (continued)
MAX205
(Circuit of Figure 1; V
= +4.75V to +5.25V, GND = 0V, max gain (B0 = B1 = B2 = B3 = B4 = 0), R = 1.13kΩ, P
= 5dBm,
OUT
CC
1
f
IN
= 70MHz, 50Ω system impedance. Typical values are at V = +5V and T = +25°C, unless otherwise noted.) (Notes 1, 2)
CC A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Gain Flatness Over 50MHz
Bandwidth
Peak-to-peak for all settings
50% control to 90% RF
0.5
dB
Attenuator Switching Time
Input Return Loss
40
15
15
12
ns
f
f
f
= 30MHz to 300MHz, all gain conditions
= 30MHz to 250MHz, all gain conditions
= 250MHz to 300MHz, all gain conditions
dB
R
R
R
Output Return Loss
dB
Note 1: Guaranteed by design and characterization.
Note 2: All limits reflect losses of external components. Output measurements are taken at RF_OUT using the application circuit
shown in Figure 1.
Note 3: The amplitude and phase unbalance are tested with 50Ω resistors connected from OUT+/OUT- to GND.
Typical Operating Characteristics
(Circuit of Figure 1, V
= 5.0V, R = 1.13kΩ, max gain (B0 = B1 = B2 = B3 = B4 = 0), P
= 5dBm, T = +25°C, unless other-
CC
1
OUT A
wise noted.)
INPUT RETURN LOSS vs. RF FREQUENCY
OUTPUT RETURN LOSS vs. RF FREQUENCY
(ALL STATES)
SUPPLY CURRENT vs. TEMPERATURE
(ALL STATES)
270
260
250
240
230
220
210
0
5
0
5
V
= 5.25V
10
15
20
25
30
35
40
10
15
20
25
30
35
40
CC
V
= 5.0V
CC
V
CC
= 4.75V
-40
-15
10
35
60
85
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
TEMPERATURE (°C)
GAIN vs. RF FREQUENCY (ALL STATES)
GAIN vs. RF FREQUENCY
GAIN vs. RF FREQUENCY
25
20
15
10
5
24
22
20
18
16
14
12
10
24
22
20
18
16
14
12
10
T
A
= -40°C
V
CC
= 4.75V
T
= +25°C
A
V
= 5.25V
CC
V
CC
= 5.0V
T
A
= +85°C
0
-5
-10
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
_______________________________________________________________________________________
3
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
= 5.0V, R = 1.13kΩ, max gain (B0 = B1 = B2 = B3 = B4 = 0), P
= 5dBm, T = +25°C, unless other-
A
CC
1
OUT
wise noted.)
ATTENUATION ABSOLUTE ACCURACY
(ALL STATES)
ATTENUATION RELATIVE ACCURACY
(ALL STATES)
REVERSE ISOLATION vs. RF FREQUENCY
1.0
0.8
1.0
0.8
40
36
32
28
24
20
0.6
0.6
MAX205
0.4
0.4
0.2
0.2
0
0
-0.2
-0.4
-0.6
-0.8
-1.0
-0.2
-0.4
-0.6
-0.8
-1.0
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
NOISE FIGURE vs. FREQUENCY
OUTPUT P-1dB vs. FREQUENCY
OUTPUT P-1dB vs. FREQUENCY
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
27
26
25
24
23
22
21
27
26
25
24
23
22
21
T
= +85°C
= -40°C
V
= +5.25V
A
CC
T
= +85°C
A
V
= +5V
T
A
= +25°C
CC
T
A
V
= +4.75V
CC
T
A
= +25°C
T
A
= -40°C
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
OUTPUT IP3 vs. FREQUENCY
OUTPUT IP3 vs. FREQUENCY
INPUT IP3 vs. ATTENUATION STATE
44
42
40
38
36
34
32
30
44
42
40
38
36
34
32
30
55
50
45
40
35
30
25
20
15
P
= P = 5dBm
RF2
RF1
AT OUTPUT, Δf = 1MHz,
= 70MHz
V
= +5.25V
CC
f
IN
V
= +5V
CC
T
A
= +85°C
T
A
= +25°C
V
= +4.75V
CC
T
= -40°C
A
P
RF1
= P = 5dBm
P
= P = 5dBm
RF1 RF2
AT OUTPUT, Δf = 1MHz
RF2
AT OUTPUT, Δf = 1MHz
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
0
4
8
12
16
20
24
ATTENUATION STATE
4
_______________________________________________________________________________________
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
MAX205
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
= 5.0V, R = 1.13kΩ, max gain (B0 = B1 = B2 = B3 = B4 = 0), P
= 5dBm, T = +25°C, unless other-
A
CC
1
OUT
wise noted.)
3RD HARMONIC vs. FREQUENCY
3RD HARMONIC vs. FREQUENCY
2ND HARMONIC vs. FREQUENCY
-55
-60
-65
-70
-75
-80
-85
-55
-60
-65
-70
-75
-80
-85
-60
-65
-70
-75
-80
-85
-90
T
A
= +85°C
T
A
= -40°C
T
A
= -40°C
V
CC
= +5.25V
T
= +25°C
V
= +5V
CC
A
V
CC
= +4.75V
T
= +85°C
A
T
= +25°C
A
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
2ND HARMONIC vs. FREQUENCY
OUTPUT IP2 vs. FREQUENCY (f + f )
OUTPUT IP2 vs. FREQUENCY (f + f )
1 2
1
2
-60
-65
-70
-75
-80
-85
-90
85
80
75
70
65
60
55
50
85
80
75
70
65
60
55
50
V
CC
= +4.75V
T
A
= +25°C
V
CC
= +5.0
V
= +5.25V
CC
V
CC
= +5.25V
V
= +4.75V
CC
T = -40°C
A
V
= +5V
T
A
= +85°C
CC
P
= P = 5dBm
RF2
P = P = 5dBm
RF1 RF2
RF1
AT OUTPUT, Δf = 1MHz
AT OUTPUT, Δf = 1MHz
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
OUTPUT-PORT AMPLITUDE UNBALANCE
vs. FREQUENCY
OUTPUT-PORT PHASE UNBALANCE
vs. FREQUENCY
0.25
0.20
0.15
0.10
0.05
0
3.0
2.5
2.0
1.5
1.0
0.5
0
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
_______________________________________________________________________________________
5
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
= 5.0V, R = 909Ω, max gain, (B0 = B1 = B2 = B3 = B4 = 0), P
= 5dBm, T = +25°C, unless otherwise
A
CC
1
OUT
noted.)
INPUT RETURN LOSS vs. RF FREQUENCY
OUTPUT RETURN LOSS vs. FREQUENCY
(ALL STATES)
(ALL STATES)
SUPPLY CURRENT vs. TEMPERATURE
0
10
20
30
40
50
60
0
270
260
250
240
230
220
210
10
20
30
40
50
MAX205
V
CC
= 5.25V
V
= 5.0V
CC
V
= 4.75V
CC
60
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
-40
-15
10
35
60
85
FREQUENCY (MHz)
TEMPERATURE (°C)
GAIN vs. RF FREQUENCY (ALL STATES)
GAIN vs. RF FREQUENCY
GAIN vs. RF FREQUENCY
25
20
15
10
5
24
22
20
18
16
14
12
10
24
22
T
A
= -40°C
V
CC
= 4.75V
20
18
16
14
12
10
T
A
= +25°C
V
= 5.25V
CC
V
= 5.0V
CC
T
= +85°C
A
0
-5
-10
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
ATTENUATION ABSOLUTE ACCURACY
(ALL STATES)
ATTENUATION RELATIVE ACCURACY
(ALL STATES)
REVERSE ISOLATION vs. RF FREQUENCY
1.0
0.8
1.0
0.8
40
36
32
28
24
20
0.6
0.6
0.4
0.4
0.2
0.2
0
0
-0.2
-0.4
-0.6
-0.8
-1.0
-0.2
-0.4
-0.6
-0.8
-1.0
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
6
_______________________________________________________________________________________
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
MAX205
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
= 5.0V, R = 909Ω, max gain, (B0 = B1 = B2 = B3 = B4 = 0), P
= 5dBm, T = +25°C, unless otherwise
A
OUT
CC
1
noted.)
NOISE FIGURE vs. FREQUENCY
OUTPUT P-1dB vs. FREQUENCY
OUTPUT P-1dB vs. FREQUENCY
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
27
26
25
24
23
22
21
27
T
A
= +85°C
26
T
A
= +85°C
V
= +5.25V
CC
25
24
23
22
21
V = +5V
CC
T
= +25°C
V
= +4.75V
A
CC
T
A
= -40°C
T
A
= +25°C
T
= -40°C
A
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
OUTPUT IP3 vs. FREQUENCY
OUTPUT IP3 vs. FREQUENCY
INPUT IP3 vs. ATTENUATION STATE
44
42
40
38
36
34
32
30
44
42
40
38
36
34
32
30
55
50
45
40
35
30
25
20
15
P
= P = 5dBm
RF2
RF1
AT OUTPUT, Δf = 1MHz,
= 70MHz
V
= +5.25V
CC
f
IN
T
A
= +25°C
V
CC
= +4.75V
V
= +5V
T
A
= +85°C
CC
T
= -40°C
A
P
RF1
= P = 5dBm
P
= P = 5dBm
RF1 RF2
RF2
AT OUTPUT, Δf = 1MHz
AT OUTPUT, Δf = 1MHz
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
0
4
8
12
16
20
24
ATTENUATION STATE
3RD HARMONIC vs. FREQUENCY
3RD HARMONIC vs. FREQUENCY
2ND HARMONIC vs. FREQUENCY
-55
-60
-65
-70
-75
-80
-85
-55
-60
-65
-70
-75
-80
-85
-50
-55
-60
-65
-70
-75
-80
-85
-90
T
= +25°C
A
T
= -40°C
A
T
A
= -40°C
V
= +5.25V
CC
V
= +5V
CC
T
A
= +85°C
T
= +25°C
T = +85°C
A
A
V
= +4.75V
CC
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
_______________________________________________________________________________________
7
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
= 5.0V, R = 909Ω, max gain, (B0 = B1 = B2 = B3 = B4 = 0), P
= 5dBm, T = +25°C, unless otherwise
CC
1
OUT A
noted.)
2ND HARMONIC vs. FREQUENCY
OUTPUT IP2 vs. FREQUENCY (f + f )
OUTPUT IP2 vs. FREQUENCY (f + f )
1
2
1
2
-50
-55
-60
-65
-70
-75
-80
-85
-90
85
80
75
70
65
60
55
50
80
75
70
65
60
55
50
T
A
= +85°C
V
CC
= +5.0V
V
= +4.75V
CC
MAX205
V
= +5.25V
CC
V
= +5.25V
CC
V
= +5V
CC
T = +25°C
A
V
= +4.75V
CC
T
A
= -40°C
P
= P = 5dBm
RF2
P = P = 5dBm
RF1 RF2
RF1
AT OUTPUT, Δf = 1MHz
AT OUTPUT, Δf = 1MHz
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
OUTPUT-PORT AMPLITUDE UNBALANCE
vs. FREQUENCY
OUTPUT-PORT PHASE UNBALANCE
vs. FREQUENCY
0.25
0.20
0.15
0.10
0.05
0
3.0
2.5
2.0
1.5
1.0
0.5
0
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
30 60 90 120 150 180 210 240 270 300
FREQUENCY (MHz)
8
_______________________________________________________________________________________
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
MAX205
Pin Description
PIN
NAME
FUNCTION
Power Supply. Bypass to GND with capacitors as close to the pin as possible as shown in the typical
application circuits (Figures 1 and 2).
1, 9
V
CC
Signal Input. Internally matched to 50Ω over the operating frequency. See the typical application
circuit for recommended component values.
2
RF_IN
Ground. Use low-inductance layout techniques on the PC board. Solder the exposed paddle to the
board ground plane.
3, 18, 20, EP
GND
B4–B0
4–8
10
Attenuation Control Bits. Digital input for attenuation control. See Table 3 for attenuation setting.
Inverted Differential Signal Output. Requires an external pullup choke inductor (120mA typical
RF_OUT-
current) to V
along with a DC-blocking capacitor; see Figures 1 and 2.
CC
Noninverted Differential Signal Output. Requires an external pullup choke inductor (120mA typical
current) to V along with a DC-blocking capacitor; see Figures 1 and 2.
11
RF_OUT+
CC
12
13
I
Amplifier Bias Input. See Figures 1 and 2 for detailed connection.
Bypass Capacitor. See Figures 1 and 2 for detailed connection.
BIAS
C
BP
Amplifier DC Ground. Requires choke inductor that can handle supply current. DC resistance of
inductor should be less than 0.2Ω.
14
L
E
15
16
17
19
AMP
Amplifier Input. Requires DC-coupling to allow biasing.
IN
C
Compensation Capacitor. Requires connection to AMP (pin 15) for stability.
IN
C
I
Connect R1 from I
to GND (see Table 1 or Table 2 for values).
SET
SET
ATTN
Attenuator Output. Requires external DC-blocking capacitor.
OUT
Table 1. Suggested Components of
Circuit of Figure 1
Table 2. Suggested Components of
Circuit of Figure 2
COMPONENT
VALUE
1nF
SIZE
0603
0603
0603
0603
1008
0603
0603
—
COMPONENT
VALUE
1nF
SIZE
0603
0603
0603
1008
0603
0603
—
C1, C3–C6, C8, C9, C10, C12
C1, C3, C4, C5, C7–C10, C12
C2, C11
L1, L3
L2
100pF
330nH
100nH
680nH
1.13kΩ
10Ω
C2, C11
L1, L2, L3
L4, L5
R1
100pF
330nH
680nH
909Ω
10Ω
L4, L5
R1
R7
R7
T2
1:1
T1, T2
1:1
_______________________________________________________________________________________
9
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
V
CC
C3
C2
C4
C6
T1
1
20
19
18
17
16
15
14
13
12
11
V
GND
CC
RF_IN
ATTN
2
3
4
5
6
7
8
9
OUT
RF_IN
MAX205
C1
GND
B4
GND
R1
I
SET
C5
B3
B2
B1
B0
C
C
1
ATTENUATION
LOGIC
CONTROL
CONTROL
INPUTS
AMP
IN
L2
L
E
C
BP
L1
R7
V
V
MAX2055
I
BIAS
CC
CC
L3
C12
C11
RF_OUT+
L4
10
RF_OUT-
V
CC
L5
C10
C8
C9
1
T2
RF_OUT
Figure 1. Typical Application Circuit
feedback to achieve high gain and linearity over a wide
bandwidth.
Detailed Description
The MAX2055 is a high-dynamic-range, digitally con-
trolled, variable-gain differential ADC driver/amplifier
(DVGA) for use in applications from 30MHz to 300MHz.
The amplifier is designed for 50Ω single-ended input
and 50Ω differential output systems.
Applications Information
Digitally Controlled Attenuator
The digital attenuator is controlled through five logic
lines: B0, B1, B2, B3, and B4. Table 3 lists the attenua-
tion settings. The input and output of this attenuator
require external DC blocking capacitors. The attenua-
tor’s insertion loss is approximately 2dB, when the con-
trol bits are set to 0dB (B0 = B1 = B2 = B3 = B4 = 0).
The MAX2055 integrates a digital attenuator with a
23dB selectable attenuation range and a high-linearity,
single-ended-to-differential output amplifier. The attenu-
ator is digitally controlled through five logic lines:
B0–B4. The on-chip attenuator provides up to 23dB of
attenuation with 0.2dB accuracy. The single-ended
input to differential output amplifier utilizes negative
Single-Ended-to-Differential Amplifier
The MAX2055 integrates a single-ended-to-differential
amplifier with a nominal gain of 22dB in a negative
10 ______________________________________________________________________________________
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
MAX205
V
CC
C3
C2
1
20
19
18
17
16
15
14
GND
V
CC
RF_IN
ATTN
OUT
2
3
4
5
6
7
8
9
RF_IN
C1
GND
GND
B4
R1
C4
I
SET
C5
B3
B2
B1
B0
C
C
ATTENUATION
LOGIC
CONTROL
CONTROL
INPUTS
AMP
IN
L2
L
E
C
BP
13
12
L1
R7
V
CC
V
C7
CC
MAX2055
I
BIAS
11
L3
C12
C11
RF_OUT-
10
RF_OUT+
L4
V
CC
L5
C10
C8
C9
1
T2
RF_OUT
Figure 2. Low-Cost Application Circuit
feedback topology. This amplifier is optimized for a fre-
quency range of operation from 30MHz to 300MHz with
a high-output third-order intercept point (OIP3). The
bias current is chosen to optimize the IP3 of the amplifi-
er. When R1 is 1.13kΩ (909Ω if using the circuit of
Figure 2), the current consumption is 240mA while
exhibiting a 40dBm typical output IP3 at 70MHz. The
common-mode inductor, L2, provides a high common-
mode rejection with excellent amplitude and phase bal-
ance at the output. L2 must handle the supply current
and have DC resistance less than 0.2Ω.
Choke Inductor
The single-ended amplifier input and differential output
ports require external choke inductors. At the input,
connect a 330nH bias inductor from AMP (pin 15) to
IN
I
(pin 12). Connect 680nH choke inductors from
BIAS
RF_OUT+ (pin 11) and RF_OUT- (pin 10) to V . These
CC
connections provide bias current to the amplifier.
Layout Considerations
A properly designed PC board is an essential part of
any RF/microwave circuit. Keep RF signal lines as short
as possible to reduce losses, radiation, and induc-
tance. For best performance, route the ground-pin
traces directly to the exposed pad underneath the
______________________________________________________________________________________ 11
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
package. This pad should be connected to the ground
Table 3. Attenuation Setting vs. Gain-
Control Bits
plane of the board by using multiple vias under the
device to provide the best RF/thermal conduction path.
Solder the exposed pad on the bottom of the device
package to a PC board exposed pad.
ATTENUATION
B4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
B3*
0
B2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
B1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
B0
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
The MAX2055 Evaluation Kit can be used as a refer-
ence for board layout. Gerber files are available upon
request at www.maxim-ic.com.
0
2
0
3
0
MAX205
Power-Supply Bypassing
4
0
Proper voltage-supply bypassing is essential for high-
5
0
frequency circuit stability. Bypass each V
pin with a
CC
6
0
1000pF and 100pF capacitor. Connect the 100pF
capacitor as close to the device as possible. Resistor
R7 helps reduce switching transients. If switching tran-
sients are not a concern, R7 is not required. Therefore,
7
0
8
1
9
1
connect pin 9 directly to V
.
CC
10
11
12
13
14
15
16
17
18
19
20
21
22
23
1
Exposed Paddle RF Thermal
Considerations
1
1
The EP of the MAX2055’s 20-pin TSSOP-EP package
provides a low thermal-resistance path to the die. It is
important that the PC board on which the IC is mounted
be designed to conduct heat from this contact. In addi-
tion, the EP provides a low-inductance RF ground path
for the device.
1
1
1
X
X
X
X
X
X
X
X
It is recommended that the EP be soldered to a ground
plane on the PC board, either directly or through an
array of plated via holes.
Soldering the pad to ground is also critical for efficient
heat transfer. Use a solid ground plane wherever
possible.
*Enabling B4 disables B3 and the minimum attenuation is
16dB.
Chip Information
TRANSISTOR COUNT: 325
PROCESS: BiCMOS
12 ______________________________________________________________________________________
Digitally Controlled, Variable-Gain, Differential
ADC Driver/Amplifier
MAX205
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
PACKAGE OUTLINE, TSSOP 4.40mm BODY
1
21-0066
I
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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