LMH2120UM/NOPB [TI]
具有 40 dB 动态范围的 6GHz 线性 RMS 功率检测器 | YFZ | 6 | -40 to 85;
| 型号： | LMH2120UM/NOPB |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 具有 40 dB 动态范围的 6GHz 线性 RMS 功率检测器 | YFZ | 6 | -40 to 85 电信 电信集成电路 |
| 文件： | 总35页 (文件大小：741K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LMH2120
www.ti.com
SNWS021C –JULY 2010–REVISED FEBRUARY 2013
LMH2120 6 GHz Linear RMS Power Detector with 40 dB Dynamic Range
Check for Samples: LMH2120
1
FEATURES
DESCRIPTION
The LMH2120 is a 40 dB Linear RMS power detector
particularly suited for accurate power measurement of
modulated RF signals that exhibit large peak-to-
average ratios, i.e, large variations of the signal
envelope. Such signals are encountered in W-CDMA
and LTE cell phones. The RMS measurement
topology inherently ensures a modulation insensitive
measurement.
2
•
•
•
•
•
•
•
•
•
•
Linear Root Mean Square Response
40 dB Linear-in-V Power Detection Range
Multi-Band Operation from 50 MHz to 6 GHz
Lin Conformance Better than ±0.5 dB
Highly Temperature Insensitive
Modulation Independent Response
Minimal Slope and Intercept Variation
Shutdown Functionality
The device has an RF frequency range from 50 MHz
to 6 GHz. It provides an accurate, temperature and
supply insensitive, output voltage that relates linearly
to the RF input power in volt. The LMH2120's
excellent conformance to a linear response enables
an easy integration by using slope and intercept only,
reducing calibration effort significantly. The device
operates with a single supply from 2.7V to 5V. The
LMH2120 has an RF power detection range from -35
dBm to 5 dBm and is ideally suited for use in
combination with a directional coupler. Alternatively, a
resistive divider can be used.
Wide Supply Range from 2.7V to 5V
Tiny 6-Bump DSBGA Package
APPLICATIONS
•
Multi Mode, Multi Band RF Power Control
–
–
–
–
–
GSM/EDGE
CDMA/CDMA2000
W-CDMA
OFDMA
The device is active for EN = High, otherwise it is in a
low power consumption shutdown mode. To save
power and prevent discharge of an external filter
capacitance, the output (OUT) is high impedance
during shutdown.
LTE
•
Infrastructure RF Power Control
The LMH2120 power detector is offered in a tiny 6-
bump DSBGA package.
10
COUPLER
ANTENNA
RF
PA
1
50W
V
DD
0.1
85°C
A1
25°C
RF
EN
IN
OUT
B1
A2
-40°C
0.01
ADC
LMH2120
-50
-40
-30
-20
-10
0
10
C2
RF INPUT POWER (dBm)
C1, B2
GND
Figure 1. Typical Application
Figure 2. Output Voltage vs. RF Input Power at
1900 MHz
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2010–2013, Texas Instruments Incorporated
LMH2120
SNWS021C –JULY 2010–REVISED FEBRUARY 2013
www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
(1)(2)
Absolute Maximum Ratings
Supply Voltage
VDD - GND
RF Input
5.5V
Input power
12 dBm
1V
DC Voltage
Enable (EN) Input Voltage
GND-0.4V < VEN and VEN<Min (VDD+0.4, 3.6V)
(3)
ESD Tolerance
Human Body Model
Machine Model
2000V
200V
Charge Device Model
Storage Temperature Range
1000V
−65°C to 150°C
150°C
(4)
Junction Temperature
For soldering specifications:
See product folder at www.ti.com and SNOA549
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test
conditions, see the Electrical Characteristics.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
(3) Human body model, applicable std. MIL-STD-883, Method 3015.7. Machine model, applicable std. JESD22–A115–A (ESD MM std of
JEDEC). Field-Induced Charge-Device Model, applicable std. JESD22–C101–C. (ESD FICDM std. of JEDEC)
(4) The maximum power dissipation is a function of TJ(MAX) , θJA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(MAX) - TA)/θJA. All numbers apply for packages soldered directly into a PC board.
(1)
Operating Ratings
Supply Voltage
2.7V to 5V
−40°C to +85°C
50 MHz to 6 GHz
−35 dBm to 5 dBm
166.7°C/W
Temperature Range
RF Frequency Range
RF Input Power Range
Package Thermal Resistance θJA
(2)
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but specific performance is not ensured. For ensured specifications and the test
conditions, see the Electrical Characteristics.
(2) The maximum power dissipation is a function of TJ(MAX) , θJA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(MAX) - TA)/θJA. All numbers apply for packages soldered directly into a PC board.
2
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SNWS021C –JULY 2010–REVISED FEBRUARY 2013
2.7 V and 4.5V DC and AC Electrical Characteristics
Unless otherwise specified, all limits are ensured to TA = 25°C, VDD = 2.7V and 4.5V (worst case of the 2 is specified), RFIN=
(1)
1900 MHz CW (Continuous Wave, unmodulated). Boldface limits apply at the temperature extremes
.
Symbol
Parameter
Condition
Min
Typ
Max
Units
(2)
(3)
(2)
Supply Interface
IDD
Supply Current
Active mode: EN = High, no signal
3.5
4.0
2.9
3.8
4.7
3.8
4.7
60
mA
µA
present at RFIN
.
Shutdown: EN = LOW,
no signal present at
RFIN
4.7
5.0
VBAT = 2.7V
VBAT = 4.5V
VBAT = 2.7V
VBAT = 4.5V
5.7
6.1
EN = LOW, RFIN = 0
dBm, 1900 MHz
4.7
5.0
µA
dB
5.7
6.1
PSRR
Power Supply Rejection Ratio
RFIN = -10 dBm, 1900 MHz, 2.7V <
VBAT < 5V
50
Logic Enable Interface
VLOW
EN logic LOW input level
(Shutdown mode)
0.6
V
VHIGH
IEN
EN logic HIGH input level
Current into EN pin
1.1
50
nA
Input / Output Interface
RIN
Input Resistance
44
50
18
56
Ω
VOUT
Minimum Output Voltage
(Pedestal)
No Input Signal
29
33
mV
ROUT
IOUT
Output Resistance
EN = HIGH, RFIN = -10 dBm, 1900
MHz, ILOAD = 1 mA, DC measurement
2
3
1
Ω
Output Sinking Current
Output Sourcing Current
RFIN = -10 dBm, 1900 MHz, OUT
connected to 2.5V
30
25
42
45
mA
RFIN = -10 dBm, 1900 MHz, OUT
connected to GND
36
31
IOUT, SD
Output Leakage Current in
Shutdown Mode
EN = LOW, OUT connected to 2V
80
nA
(4)
en
vn
Output Referred Noise
RFIN = -10 dBm, 1900 MHz, output
spectrum at 10 kHz
5
µV/√Hz
µVRMS
Output Referred Noise Integrated Integrated over frequency band 1 kHz -
390
(4)
6.5 kHz, RFIN = -10 dBm, 1900 MHz
Timing Characteristics
tON Turn-on Time from shutdown
RFIN = -10 dBm, 1900 MHz, EN LOW-
to-HIGH transition to OUT at 90%
13
7
18
µs
µs
µs
tR
Rise Time
Fall Time
Signal at RFIN from -20 dBm to 0 dBm,
10% to 90%, 1900 MHz
tF
Signal at RFIN from 0 dBm to -20 dBm,
90% to 10%, 1900 MHz
18
(1) Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very
limited self-heating of the device such that TJ = TA. No specification of parametric performance is indicated in the electrical tables under
conditions of internal self-heating where TJ > TA.
(2) All limits are ensured by test or statistical analysis.
(3) Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary
over time and will also depend on the application and configuration. The typical values are not tested and are not specified on shipped
production material.
(4) This parameter is ensured by design and/or characterization and is not tested in production.
Copyright © 2010–2013, Texas Instruments Incorporated
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2.7 V and 4.5V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured to TA = 25°C, VDD = 2.7V and 4.5V (worst case of the 2 is specified), RFIN=
1900 MHz CW (Continuous Wave, unmodulated). Boldface limits apply at the temperature extremes (1)
.
Symbol
Parameter
Condition
Min
Typ
Max
Units
(2)
(3)
(2)
RF Detector Transfer, fit range -15 dBm to -5 dBm for Linear Slope and Intercept
RFIN = 50 MHz(5)
PMIN
Minimum Power Level, bottom
end of Dynamic Range
Log Conformance Error within ±1 dB
-37
4
dBm
PMAX
Maximum Power Level, top end of
Dynamic Range
VMIN
VMAX
KSLOPE
PINT
Minimum Output Voltage
Maximum Output Voltage
Linear Slope
At PMIN
At PMAX
31
2.6
1
mV
V
dB/dB
dBm
Linear Intercept
VOUT = 0 dBV
-5.7
-5.5
-5.3
DR
Dynamic Range for specified
Accuracy
±1 dB Lin Conformance Error (ELC
)
)
37
36
41
40
±3 dB Lin Conformance Error (ELC
44
48
dB
43
47
±0.5 dB Variation over Temperature
(EVOT
41
45
)
RFIN = 900 MHz(5)
PMIN
Minimum Power Level, bottom
end of Dynamic Range
Lin Conformance Error within ±1 dB
-35
5
dBm
PMAX
Maximum Power Level, top end of
Dynamic Range
VMIN
VMAX
KSLOPE
PINT
Minimum Output Voltage
Maximum Output Voltage
Linear Slope
At PMIN
At PMAX
33
2.5
1
mV
V
dB/dB
dBm
Linear Intercept
VOUT = 0 dBV
-4.2
-4.0
-3.8
DR
Dynamic Range for specified
Accuracy
±1 dB Lin Conformance Error (ELC
)
)
36
33
40
37
±3 dB Lin Conformance Error (ELC
45
48
44
47
±0.5 dB Variation over Temperature
(EVOT
41
44
dB
)
±0.3 dB Error for a 1dB Power Step
(E1dB
41
40
)
±1 dB Error for a 10dB Power Step
(E10dB
45
)
EMOD
Input referred Variation due to
Modulation
W-CDMA Release 6/7/8,
-35 dBm<RFIN<-3 dBm
0.15
0.29
dB
LTE, -35 dBm<RFIN<-3 dBm
RFIN = 1900 MHz(5)
PMIN
Minimum Power Level, bottom
end of Dynamic Range
Lin Conformance Error within ±1 dB
-34
4
dBm
PMAX
Maximum Power Level, top end of
Dynamic Range
VMIN
Minimum Output Voltage
Maximum Output Voltage
Linear Slope
At PMIN
At PMAX
30
1.7
1
mV
V
VMAX
KSLOPE
PINT
dB/dB
dBm
Linear Intercept
VOUT = 0 dBV
-2.2
-1.8
-1.4
(5) Limits are ensured by design and measurements which are performed on a limited number of samples.
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SNWS021C –JULY 2010–REVISED FEBRUARY 2013
2.7 V and 4.5V DC and AC Electrical Characteristics (continued)
Unless otherwise specified, all limits are ensured to TA = 25°C, VDD = 2.7V and 4.5V (worst case of the 2 is specified), RFIN=
1900 MHz CW (Continuous Wave, unmodulated). Boldface limits apply at the temperature extremes (1)
.
Symbol
Parameter
Condition
Min
Typ
Max
Units
(2)
(3)
(2)
DR
Dynamic Range for specified
Accuracy
±1 dB Lin Conformance Error (ELC
±3 dB Lin Conformance Error (ELC
)
)
35
31
38
35
44
48
41
45
±0.5 dB Variation over Temperature
(EVOT
35
40
dB
)
±0.3 dB Error for a 1dB Power Step
(E1dB
39
36
)
±1 dB Error for a 10dB Power Step
(E10dB
35
)
EMOD
Input referred Variation due to
Modulation
W-CDMA Release 6/7/8,
-34 dBm<RFIN<-2 dBm
0.16
0.24
dB
LTE, -34 dBm<RFIN<-2 dBm
RFIN = 2600 MHz(5)
PMIN
Minimum Power Level, bottom
end of Dynamic Range
Lin Conformance Error within ±1 dB
-30
6
dBm
PMAX
Maximum Power Level, top end of
Dynamic Range
VMIN
VMAX
KSLOPE
PINT
Minimum Output Voltage
Maximum Output Voltage
Linear Slope
At PMIN
At PMAX
31
1.5
1
mV
V
dB/dB
dBm
Linear Intercept
VOUT = 0 dBV
0.8
1.7
2.6
DR
Dynamic Range for specified
Accuracy
±1 dB Lin Conformance Error (ELC
)
)
32
29
36
33
±3 dB Lin Conformance Error (ELC
43
45
dB
40
42
±0.5 dB Variation over Temperature
(EVOT
34
39
)
RFIN = 3500 MHz(6)
PMIN
Minimum Power Level, bottom
end of Dynamic Range
Lin Conformance Error within ±1 dB
-26
7
dBm
PMAX
Maximum Power Level, top end of
Dynamic Range
VMIN
VMAX
KSLOPE
PINT
Minimum Output Voltage
Maximum Output Voltage
Linear Slope
At PMIN
At PMAX
32
1.1
1
mV
V
dB/dB
dBm
Linear Intercept
VOUT = 0 dBV
4.4
5.5
6.7
DR
Dynamic Range for specified
Accuracy
±1 dB Lin Conformance Error (ELC
)
)
30
27
33
30
±3 dB Lin Conformance Error (ELC
39
42
dB
36
40
±0.5 dB Variation over Temperature
(EVOT
27
35
)
(6) Limits are ensured by design and measurements which are performed on a limited number of samples.
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CONNECTION DIAGRAM
V
A1
B1
C1
A2
B2
C2
OUT
GND
EN
DD
RF
IN
GND
Figure 3. 6-Bump DSBGA
Top View
PIN DESCRIPTIONS
DSBGA
A1
Name
Description
Power
Supply
VDD
Positive Supply Voltage.
C1
GND
EN
Ground. Both C1 and B2 need to be connected to GND.
B2
Logic Input
C2
The device is enabled for EN = High, and in shutdown mode for EN = LOW. EN should be
<2.5V when IEN is LOW. For EN >2.5V, IEN increases slightly while the device is still
functional. Absolute maximum rating for EN = 3.6V.
Analog
Input
B1
A2
RFIN
OUT
RF input signal to the detector, internally terminated with 50 Ω.
Output
Ground referenced detector output voltage.
BLOCK DIAGRAM
A1
V
DD
LDO
Internal Supply
V/I
V/I
RF
IN
B1
OUT A2
A
C2
V/I
V/I
EN
GND
C1, B2
Figure 4. LMH2120
6
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SNWS021C –JULY 2010–REVISED FEBRUARY 2013
Typical Performance Characteristics
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
Supply Current
vs.
Supply Voltage (Active)
Supply Current
vs.
Supply Voltage (Shutdown)
8
7
6
5
4
3
2
1
0
5
4
3
2
1
0
0
1
2
3
4
5
6
0
1
2
3
4
5
6
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
Figure 5.
Figure 6.
Supply Current
vs.
Enable Voltage (EN)
Supply Current
vs.
RF Input Power
5
6
5
4
3
2
1
0
4
3
2
1
0
85°C
25°C
-40°C
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2
-50
-40
-30
-20
-10
0
10
ENABLE VOLTAGE (V)
RF INPUT POWER (dBm)
Figure 7.
Figure 8.
Output Sourcing Current
Output Sinking Current
vs.
vs.
RF Input Power
60
RF Input Power
60
50
40
30
20
10
0
50
40
-40°C
25°C
-40°C
25°C
30
85°C
85°C
20
10
OUT = 0V
RFin = 1900 MHz
OUT = 2.5V
RFin = 1900 MHz
0
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10 10
0
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 9.
Figure 10.
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Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
RF Input Impedance
vs.
Power Supply Rejection Ratio
Frequency,
Resistance (R) and Reactance (X)
vs.
Frequency
70
100
R
75
60
50
50
25
40
0
30
-25
X
20
-50
10
-75
MEASURED ON BUMP
-100
0
10
100
1k
10k
100k
10M
100M
1G
10G
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 11.
Figure 12.
Output Voltage Noise
Lin Slope
vs.
Frequency
vs.
Frequency
8
7
6
5
4
3
2
1
1.3
PIN = -10 dBm
1.2
1.1
1.0
0.9
0.8
0.7
-40°C
85°C
25°C
0
10
100
1k
10k
100k
1M
10M
100M
1G
10G
FREQUENCY (Hz)
FREQUENCY (Hz)
Figure 13.
Figure 14.
Lin Intercept
vs.
Frequency
Output Voltage
vs.
RF Input Power
10
1
12
10
8
6
4
2
0
0.1
0.01
-2
-4
-6
25°C
85°C
-40°C
-8
10M
-50
-40
-30
-20
-10
0
10
100M
1G
10G
FREQUENCY (Hz)
RF INPUT POWER (dBm)
Figure 15.
Figure 16.
8
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SNWS021C –JULY 2010–REVISED FEBRUARY 2013
Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
Output Voltage
Output Voltage
vs.
vs.
Frequency
RF Input Power at 50 MHz
10
1
10
1
0.1
0.01
0.1
0.01
85°C
25°C
100M
-40°C
-30
10M
1G
10G
-50
-40
-20
-10
0
10
RF INPUT POWER (dBm)
FREQUENCY (Hz)
Figure 17.
Figure 18.
Lin Conformance
vs.
RF Input Power at 50 MHz
Lin Conformance (50 units) vs.
RF Input Power at 50 MHz
3
3
2
1
2
1
-40°C
85°C
0
0
-1
-2
-3
-1
-2
-3
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 19.
Figure 20.
Temperature Variation
vs.
RF Input Power at 50 MHz
Temperature Variation (50 units) vs.
RF Input Power at 50 MHz
2.0
2.0
1.5
1.5
1.0
1.0
0.5
0.5
0.0
0.0
-0.5
-1.0
-1.5
-2.0
-0.5
-1.0
-1.5
-2.0
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 21.
Figure 22.
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Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
Output Voltage
Lin Conformance
vs.
vs.
RF Input Power at 900 MHz
RF Input Power at 900 MHz
10
1
3
2
1
0
0.1
-1
-2
-3
85°C
25°C
-40°C
-30
0.01
-50
-40
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 23.
Figure 24.
Temperature Variation
vs.
RF Input Power at 900 MHz
Lin Conformance (50 units) vs.
RF Input Power at 900 MHz
3
2.0
1.5
1.0
2
1
-40°C
85°C
0.5
0
0.0
-0.5
-1.0
-1.5
-2.0
-1
-2
-3
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 25.
Figure 26.
Temperature Variation (50 units) vs.
RF Input Power at 900 MHz
1 dB Power Step Error vs.
RF Input Power at 900 MHz
2.0
1.5
1.5
1.2
0.9
1.0
0.6
0.5
0.3
0.0
0.0
-0.3
-0.6
-0.9
-1.2
-1.5
-0.5
-1.0
-1.5
-2.0
25°C
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 27.
Figure 28.
10
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SNWS021C –JULY 2010–REVISED FEBRUARY 2013
Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
W-CDMA variation
10 dB Power Step Error vs.
RF Input Power at 900 MHz
vs.
RF Input Power at 900 MHz
1.5
1.0
2.0
1.5
1.0
0.5
0.5
0.0
0.0
W-CDMA, REL6
W-CDMA, REL7
-0.5
-1.0
-1.5
-2.0
-0.5
-1.0
-1.5
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 29.
Figure 30.
LTE variation
vs.
RF Input Power at 900 MHz
Output Voltage
vs.
RF Input Power at 1900 MHz
1.5
10
1
20 MHz, 100 RB
1.0
0.5
0.0
LTE, QPSK
-0.5
-1.0
-1.5
0.1
0.01
85°C
25°C
LTE, 16 QAM
-40°C
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 31.
Figure 32.
Lin Conformance
vs.
RF Input Power at 1900 MHz
Lin Conformance (50 units) vs.
RF Input Power at 1900 MHz
3
2
3
2
85°C
1
1
0
0
-1
-2
-3
-1
-2
-40°C
-3
-50
-50
-40
-30
-20
-10
0
10
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 33.
Figure 34.
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Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
Temperature Variation
vs.
Temperature Variation (50 units) vs.
RF Input Power at 1900 MHz
2.0
RF Input Power at 1900 MHz
2.0
1.5
1.5
1.0
1.0
0.5
0.0
0.5
0.0
-0.5
-0.5
-1.0
-1.5
-2.0
-1.0
-1.5
-2.0
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 35.
Figure 36.
1 dB Power Step Error vs.
RF Input Power at 1900 MHz
10 dB Power Step Error vs.
RF Input Power at 1900 MHz
2.0
1.5
1.2
0.9
1.5
1.0
0.6
0.5
0.3
0.0
0.0
-0.3
-0.6
-0.9
-1.2
-1.5
-0.5
-1.0
-1.5
-2.0
25°C
-50
-40
-30
-20
-10
0
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 37.
Figure 38.
W-CDMA variation
vs.
RF Input Power at 1900 MHz
LTE variation
vs.
RF Input Power at 1900 MHz
1.5
1.0
1.5
20 MHz, 100 RB
1.0
0.5
0.0
0.5
LTE, QPSK
0.0
W-CDMA, REL6
W-CDMA, REL7
-0.5
-1.0
-1.5
-0.5
-1.0
-1.5
LTE, 16 QAM
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 39.
Figure 40.
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Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
Output Voltage
Lin Conformance
vs.
vs.
RF Input Power at 2600 MHz
RF Input Power at 2600 MHz
10
1
3
2
1
0
0.1
-1
-2
-3
85°C
25°C
-40°C
-20
0.01
-50
-40
-30
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 41.
Figure 42.
Temperature Variation
vs.
RF Input Power at 2600 MHz
Lin Conformance (50 units) vs.
RF Input Power at 2600 MHz
2.0
3
2
1
0
1.5
1.0
85°C
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-1
-40°C
-2
-3
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 43.
Figure 44.
Output Voltage
vs.
RF Input Power at 3500 MHz
Temperature Variation (50 units) vs.
RF Input Power at 2600 MHz
10
1
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
0.1
85°C
25°C
-40°C
-20
0.01
-50
-40
-30
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 45.
Figure 46.
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Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
Lin Conformance
vs.
Lin Conformance (50 units) vs.
RF Input Power at 3500 MHz
RF Input Power at 3500 MHz
3
2
3
2
85°C
1
1
0
0
-1
-2
-3
-1
-2
-3
-40°C
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 47.
Figure 48.
Temperature Variation
vs.
RF Input Power at 3500 MHz
Temperature Variation (50 units) vs.
RF Input Power at 3500 MHz
2.0
2.0
1.5
1.5
1.0
1.0
0.5
0.5
0.0
0.0
-0.5
-1.0
-1.5
-2.0
-0.5
-1.0
-1.5
-2.0
-40°C
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 49.
Figure 50.
Output Voltage
vs.
RF Input Power at 5800 MHz
Lin Conformance
vs.
RF Input Power at 5800 MHz
10
1
3
2
85°C
1
0
-40°C
0.1
-1
-2
-3
85°C
25°C
25°C
-40°C
0.01
-50
-40
-30
-20
-10
0
10
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
RF INPUT POWER (dBm)
Figure 51.
Figure 52.
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Typical Performance Characteristics (continued)
Unless otherwise specified TA = 25°C, VBAT = 2.7V, RFIN = 1900 MHz CW (Continuous Wave, unmodulated). Specified errors
are input referred.
Temperature Variation
vs.
RF Input Power at 5800 MHz
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 53.
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APPLICATION INFORMATION
The LMH2120 is a 40 dB Linear RMS power detector particularly suited for accurate power measurements of
modulated RF signals that exhibit large peak-to-average ratios (PAR’s). The RMS detector implements the exact
definition of power resulting in a power measurement insensitive to high PAR’s. Such signals are encountered,
e.g, in LTE and W-CDMA applications. The LMH2120 has an RF frequency range from 50 MHz to 6 GHz. It
provides an output voltage that relates linearly to the RF input power in volt. Its output voltage is highly
insensitive to temperature and supply variations.
TYPICAL APPLICATION
The LMH2120 can be used in a wide variety of applications like LTE, W-CDMA, CDMA and GSM. This section
discusses the LMH2120 in a typical transmit power control loop for such applications.
Transmit-power-control-loop circuits make the transmit-power level insensitive to power amplifier (PA)
inaccuracy. This is desirable because power amplifiers are non-linear devices and temperature dependent,
making it hard to estimate the exact transmit power level. If a control loop is used, the inaccuracy of the PA is
eliminated from the overall accuracy of the transmit power level. The accuracy of the transmit power level now
depends on the RF detector accuracy instead. The LMH2120 is especially suited for transmit-power control
applications, since it accurately measures transmit power and is insensitive to temperature, supply voltage and
modulation variations.
Figure 54 shows a simplified schematic of a typical transmit-power control system. The output power of the PA is
measured by the LMH2120 through a directional coupler. The measured output voltage of the LMH2120 is
digitized by the ADC inside the baseband chip. Accordingly, the baseband controls the PA output power level by
changing the gain control signal of the RF VGA. Although the output ripple of the LMH2120 is typically low
enough, an optional low-pass filter can be placed in between the LMH2120 and the ADC to further reduce the
ripple.
COUPLER
VGA
PA
RF
GAIN
ADC
ANTENNA
50W
B
A
S
E
B
A
N
D
V
DD
OPTIONAL
R
S
A1
RF
IN
OUT
EN
B1
A2
C
S
LMH2120
EN
C2
B2, C1
GND
Figure 54. Transmit-Power Control System
ACCURATE POWER MEASUREMENT
Detectors have evolved over the years along with the communication standards. Newer communication
standards like LTE and W-CDMA raise the need for more advanced accurate power detectors. To be able to
distinguish the various detector types it is important to understand what the ideal power measurement should
look like and how a power measurement is implemented.
Power is a metric for the average energy content of a signal. By definition it is not a function of the signal shape
over time. In other words, the power content of a 0 dBm sine wave is identical to the power content of a 0 dBm
square wave or a 0 dBm W-CDMA signal; all these signals have the same average power content.
The average power can be described by the following formula:
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2
v(t)2
R
VRMS
R
T
1
T
P =
dt =
—
0
(1)
where T is the time interval over which is averaged, v(t) is the instantaneous voltage at time t, R is the resistance
in which the power is dissipated, and VRMS is the equivalent RMS voltage.
According to aforementioned formula for power, an exact power measurement can be done by measuring the
RMS voltage (VRMS) of a signal. The RMS voltage is described by:
v(t)2dt
1
T
VRMS
=
—
(2)
Implementing the exact formula for RMS can be difficult however. A simplification can be made in determining
the average power when information about the waveform is available. If the signal shape is known, the
relationship between RMS value and, for instance, the peak value of the RF signal is also known. It thus enables
a measurement based on measuring peak voltage rather than measuring the RMS voltage. To calculate the
RMS value (and therewith the average power), the measured peak voltage is translated into an RMS voltage
based on the waveform characteristics. A few examples:
•
•
•
Sine wave: VRMS = VPEAK / √2
Square wave: VRMS = VPEAK
Saw-tooth wave: VRMS = VPEAK / √3
For more complex waveforms it is not always easy to determine the exact relationship between RMS value and
peak value. A peak measurement can therefore become impractical. An approximation can be used for the VRMS
to VPEAK relationship, but it can result in a less accurate average power estimate.
Depending on the detection mechanism, power detectors may produce a slightly different output signal in
response to the earlier mentioned waveforms, even though the average power level of these signals are the
same. This error is due to the fact that not all power detectors strictly implement the definition for signal power,
being the root mean square (RMS) of the signal. To cover for the systematic error in the output response of a
detector, calibration can be used. After calibration a look-up table corrects for the error. Multiple look-up tables
can be created for different modulation schemes.
TYPES OF RF DETECTORS
This section provides an overview of detectors based on their detection principle. Detectors that will be discussed
are:
•
•
•
Peak Detectors
LOG Amp Detectors
RMS Detectors
Peak Detectors
A peak detector is one of the simplest type of detector, storing the highest value arising in a certain time window.
However, a peak detector is typically used with a relatively long holding time when compared to the carrier
frequency and a relatively short holding time with respect to the envelope frequency. In this way a peak detector
is used as AM demodulator or envelope tracker (Figure 55).
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PEAK
ENVELOPE
CARRIER
Figure 55. Peak Detection vs. Envelope Tracking
A peak detector usually has a linear response. An example of this is a diode detector (Figure 56). The diode
rectifies the RF input voltage; subsequently, the RC filter determines the averaging (holding) time. The selection
of the holding time configures the diode detector for its particular application. For envelope tracking, a relatively
small RC time constant is chosen such that the output voltage tracks the envelope nicely. In contrast, a
configuration with a relatively large time constant measures the maximum (peak) voltage of a signal.
Z
0
D
V
REF
C
R
V
OUT
Figure 56. Diode Detector
Since peak detectors measure a peak voltage, their response is inherently dependent on the signal shape or
modulation form as discussed in the previous section. Knowledge about the signal shape is required to
determine an RMS value. For complex systems having various modulation schemes, the amount of calibration
and look-up tables can become unmanageable.
LOG Amp Detectors
LOG Amp detectors are widely used RF power detectors for GSM and the early W-CDMA systems. The transfer
function of a LOG amp detector has a linear-in-dB response, which means that the output in volts changes
linearly with the RF power in dBm. This is convenient since most communication standards specify transmit
power levels in dBm as well. LOG amp detectors implement the logarithmic function by a piecewise linear
approximation. Consequently, the LOG amp detector does not implement an exact power measurement, which
implies a dependency on the signal shape. In systems using various modulation schemes calibration and lookup
tables might be required.
RMS Detectors
An RMS detector has a response that is insensitive to the signal shape and modulation form. This is because its
operation is based on exact determination of the average power, i.e. it implements:
v(t)2dt
1
T
VRMS
=
—
(3)
RMS detectors are particularly suited for the newer communication standards like W-CDMA and LTE that exhibit
large peak-to-average ratios and different modulation schemes (signal shapes). This is a key advantage
compared to other types of detectors in applications that employ signals with high peak-to-average power
variations or different modulation schemes. For example, the RMS detector response to a 0 dBm modulated W-
CDMA signal and a 0 dBm unmodulated carrier is essentially equal. This eliminates the need for long calibration
procedures and large calibration tables in the application due to different applied modulation schemes.
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LMH2120 RF POWER DETECTOR
For optimal performance, the LMH2120 needs to be configured correctly in the application. The detector will be
discussed by means of its block diagram (Figure 57). Details of the electrical interfacing are separately discussed
for each pin below.
A1
V
DD
LDO
Internal Supply
V/I
V/I
i
i
1
RF
IN
B1
OUT A2
V
i
A
OUT
OUT
2
C2
V/I
V/I
EN
GND
C1, B2
Figure 57. Block Diagram
For measuring the RMS (power) level of a signal, the time average of the squared signal needs to be measured
as described in section ACCURATE POWER MEASUREMENT. This is implemented in the LMH2120 by means
of a multiplier and a low-pass filter in a negative-feedback loop. A simplified block diagram of the LMH2120 is
depicted in Figure 57. The core of the loop is a multiplier. The two inputs of the multiplier are fed by (i1, i2):
i1 = iLF + iRF
i1 = iLF - iRF
(4)
(5)
in which iLF is a current depending on the DC output voltage of the RF detector and iRF is a current depending on
the RF input signal. The output of the multiplier (iOUT) is the product of these two current and equals:
2
iLF2 - iRF
iOUT
=
I0
(6)
in which I0 is a normalizing current. By a low-pass filter at the output of the multiplier the DC term of this current
is isolated and integrated. The input of the amplifier A acts as the nulling point of the negative feedback loop,
yielding:
iLF2dt = iRF2dt
—
—
(7)
which implies that the average power content of the current related to the output voltage of the LMH2120 is
made equal to the average power content of the current related to the RF input signal.
For a negative-feedback system, the transfer function is given by the inverse function of the feedback block.
Therefore, to have a linear transfer for this RF detector, the feedback network implements a linear function as
well resulting in an overall transfer function for the LMH2120 of:
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VOUT = k
vRF2dt
—
(8)
in which k is the conversion gain. Note that as a result of the feedback loop a square root is also implemented,
yielding the RMS function.
Given this architecture for the RF detector, the high performance of the LMH2120 can be understood. In theory
the accuracy of the linear transfer is set by:
•
•
The linear feedback network, which basically needs to process a DC signal only.
A high loop gain for the feedback loop, which is ensured by the amplifier gain A.
The RMS functionality is inherent to the feedback loop and the use of a multiplier. Thus, a very accurate LIN-
RMS RF power detector is obtained.
To ensure a low dependency on the supply voltage, the internal detector circuitry is supplied via a low drop-out
(LDO) regulator. This enables the usage of a wide range of supply voltage (2.7V to 5V) in combination with a low
sensitivity of the output signal for the external supply voltage.
RF Input
RF systems typically use a characteristic impedance of 50Ω; the LMH2120 is no exception to this. The RF input
pin of the LMH2120 has an input impedance of 50Ω. It enables an easy, direct connection to a directional
coupler without the need for additional components (Figure 54). For an accurate power measurement the input
power range of the LMH2120 needs to be aligned with the output power range of the power amplifier. This can
be done by selecting a directional coupler with the appropriate coupling factor.
Since the LMH2120 has a constant input impedance, a resistive divider can also be used instead of a directional
coupler (Figure 58).
ANTENNA
RF
PA
R
1
V
DD
A1
RF
EN
IN
OUT
B1
A2
ADC
LMH2120
C2
B2, C1
GND
Figure 58. Application with Resistive Divider
Resistor R1 implements an attenuator, together with the detector input impedance, to match the output range of
the PA with the input range of the LMH2120. The attenuation (AdB) realized by R1 and the effective input
impedance (RIN) of the LMH2120 equals:
R1 ÿ
»
AdB = 20LOG 1 +
…
Ÿ
RIN
⁄
(9)
Solving this expression for R1 yields:
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A
dB
»
ÿ
20
…
Ÿ
10
R1 =
- 1 RIN
⁄
(10)
Suppose the desired attenuation is 30 dB with a given LMH2120 input impedance of 50Ω, the resistor R1 needs
to be 1531Ω. A practical value is 1.5 kΩ. Although this is a cheaper solution than the application with directional
coupler, it has a disadvantage. After calculating the resistor value it is possible that the realized attenuation is
less than expected. This is because of the parasitic capacitance of resistor R1 which results in a lower actual
realized attenuation. Whether the attenuation will be reduced depends on the frequency of the RF signal and the
parasitic capacitance of resistor R1. Since the parasitic capacitance varies from resistor to resistor, exact
determination of the realized attenuation can be difficult. A way to reduce the parasitic capacitance of resistor R1
is to realize it as a series connection of several separate resistors.
Enable
To save power, the LMH2120 can be brought into a low-power shutdown mode by means of the enable pin (EN).
The device is active for EN = HIGH (VEN > 1.1V), and in the low-power shutdown mode for EN = LOW (VEN
<
0.6V). In this state the output of the LMH2120 is switched to high-impedance. This high impedance prevents the
discharge of the optional low-pass filter which is good for power efficiency. Using the shutdown function, care
must be taken not to exceed the absolute maximum ratings. Since the device has an internal operating voltage of
2.5V, the voltage level on the enable should not be higher than 3V to prevent excess current flowing into the
enable pin. Also enable voltage levels lower than 400 mV below GND should be prevented. In both cases the
ESD devices start to conduct when the enable voltage range is exceeded and excess current will be drawn. A
correct operation is not ensured then. The absolute maximum ratings are also exceeded when EN is switched to
HIGH (from shutdown to active mode) while the supply voltage is switched off. This situation should be prevented
at all times. A possible solution to protect the device is to add a resistor of 1 kΩ in series with the enable input to
limit the current.
Output
The output of the LMH2120 provides a DC voltage that is a measure for the applied RF power to the input pin.
The output voltage has a linear-in-V response for an applied RF signal.
RF power detectors can have some residual ripple on the output due to the modulation of the applied RF signal.
The residual ripple on the LMH2120’s output is small; therefore, additional filtering is usually not needed. This is
because its internal averaging mechanism reduces the ripple significantly. For some modulation types having
very high peak-to-average ratios or low-frequency components in the amplitude modulation, additional filtering
might be useful.
Filtering can be applied by an external low-pass filter. It should be realized that filtering reduces not only the
ripple, but also increases the response time. In other words, it takes longer before the output reaches its final
value. A trade-off should be made between allowed ripple and allowed response time. The filtering technique is
depicted in Figure 59. The low-pass output filter is realized by resistor RS and capacitor CS. The -3 dB bandwidth
of this filter can be calculated by:
f−3 dB = 1 / (2πRSCS)
(11)
V
DD
R
S
RF
IN
OUT
A1
B1
A2
+
C
S
LMH2120
ADC
EN
C2
B2,C1
-
GND
Figure 59. Low-Pass Output Filter for Residual Ripple Reduction
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The output impedance of the LMH2120 is HIGH in shutdown. This is especially beneficial in pulsed mode
systems. It ensures a fast settling time when the device returns from shutdown into active mode and reduces
power consumption.
In pulse mode systems, the device is active only during a fraction of the time. During the remaining time the
device is in low-power shutdown. Pulsed mode system applications usually require that the output value is
available at all times. This can be realized by a capacitor connected between the output and GND that “stores”
the output voltage level. To apply this principle, discharging of the capacitor should be minimized in shutdown
mode. The connected ADC input should thus have a high input impedance to prevent a possible discharge path
through the ADC. When an additional filter is applied at the output, the capacitor of the RC-filter can be used to
store the output value. An LMH2120 with a high-impedance shutdown mode saves power in pulse mode
systems. This is because the capacitor CS doesn’t need to be fully recharged each cycle.
Supply
The LMH2120 has an internal LDO to handle supply voltages between 2.7V to 5V. This enables a direct
connection to the battery in cell phone applications. The high PSRR of the LMH2120 ensures that the
performance is constant over its power supply range.
SPECIFYING DETECTOR PERFORMANCE
The performance of the LMH2120 can be expressed by a variety of parameters. This section discusses the key
parameters.
Dynamic Range
The LMH2120 is designed to have a predictable and accurate response over a certain input power range. This is
called the dynamic range (DR) of a detector. For determining the dynamic range a couple of different criteria can
be used. The most commonly used ones are:
•
•
•
•
Linear conformance error, ELC
Variation over temperature error, EVOT
1 dB step error, E1 dB
Variation due to Modulation, EMOD
The specified dynamic range is the range in which the specified error metric is within a predefined window. An
explanation of these errors is given in the following paragraphs.
Linear Conformance error
The LMH2120 implements a linear detection function. In order to describe how close the transfer is to an ideal
linear function the linear conformance error is used. To calculate the linear conformance error the detector
transfer function is modeled as a linear-in-V relationship between the input power and the output voltage.
The ideal linear-in-V transfer is modeled by 2 parameters:
•
•
Slope, KSLOPE
Intercept, PINT
and is described by:
VOUT = KSLOPE (PIN – PINT
)
(12)
where VOUT is the output voltage in dBV, KSLOPE is the slope of the function in dB/dB, PIN the input power level in
dBm and PINT is the power level in dBm at which the function intersects VOUT = 0 dBV = 1V (See Figure 60).
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10
1
P
= RF at V is 0 dBV (1V)
IN OUT
INT
P
INT
0.1 Detector
response
K
SLOPE
Ideal LIN function
-30 -20 -10
RF INPUT POWER (dBm)
0.01
-50
-40
0
10
Figure 60. Ideal Linear Response
To determine the linear conformance error two steps are required:
1. Determine the best fitted line at 25°C.
2. Determine the difference between the actual data and the best fitted line.
The best fit can be determined by standard routines. A careful selection of the fit range is important. The fit range
should be within the normal range of operation of the device. Outcome of the fit is KSLOPE and PINT
.
Subsequently, the difference between the actual data and the best fitted line is determined. The linear
conformance is specified as an input referred error. The output referred error is therefore divided by the KSLOPE to
obtain the input referred error. The linear conformance error is calculated by the following equation:
VOUT (T) - KSLOPE 25°C
PIN - PINT 25°C
(
)
ELC(T)
=
KSLOPE 25°C
(13)
where VOUT
is the measured output voltage at a power level at PIN at a specific temperature. KSLOPE
(T)
25°C
(dB/dB) and PINT 25°C (dBm) are the parameters of the best fitted line of the 25°C transfer.
Figure 61 shows that both the error with respect to the ideal LIN response as well as the error due to
temperature variation are included in this error metric. This is because the measured data for all temperatures is
compared to the fitted line at 25°C. The measurement result of a typical LMH2120 in Figure 61 shows a dynamic
range of 35 dB for ELC= ±1dB.
3
2
1
0
-1
-2
-3
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 61. ELC vs. RF input Power at 1900 MHz
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Variation over Temperature Error
In contrast to the linear conformance error, the variation over temperature error (EVOT) purely measures the error
due to temperature variation. The measured output voltage at 25°C is subtracted from the output voltage at
another temperature. Subsequently, it is translated into an input referred error by dividing it by KSLOPE at 25°C.
The equation for variation over temperature is given by:
EVOT = (VOUT_TEMP - VOUT 25°C) / KSLOPE
(14)
The variation over temperature is shown in Figure 62, where a dynamic range of 40 dB is obtained for EVOT
±0.5 dB.
=
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 62. EVOT vs. RF Input Power at 1900 MHz
1 dB Step Error
This parameter is a measure for the error for an 1 dB power step. According to a 3GPP specification, the error
should be less than ±0.3 dB. This condition is often used to define a useful dynamic range of the detector.
The 1 dB step error is calculated in 2 steps:
1. Determine the maximum sensitivity.
2. Calculate the 1 dB step error.
First the maximum sensitivity (SMAX) is calculated per temperature. It is defined as the maximum difference
between two output voltages for a 1 dB step within the power range:
SMAX = VOUT P+1 - VOUT P
(15)
The 1dB error is than calculated by:
E1 dB = (SACTUAL - SMAX) / SMAX
(16)
where SACTUAL (actual sensitivity) is the difference between two output voltages for a 1 dB step at a given power
level. Figure 63 shows the typical 1 dB step error at 1900 MHz, where a dynamic range of 36 dB over
temperature is obtained for E1dB = ±0.3 dB.
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1.5
1.2
0.9
0.6
0.3
0.0
-0.3
-0.6
-0.9
-1.2
-1.5
25°C
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 63. 1 dB Step Error vs. RF Input Power at 1900 MHz
10 dB step error
This error is defined in a different manner than the 1 dB step error. This parameter shows the input power error
over temperature for a 10 dB power step. The 10 dB step at 25°C is taken as a reference.
To determine the 10 dB step error first the output voltage levels (V1 and V2) for power levels “P” and “P+10dB”
at the 25°C are determined (Figure 64). Subsequently these 2 output voltages are used to determine the
corresponding power levels at temperature T (PT and PT+X). The difference between those two power levels
minus 10 results in the 10 dB step error.
25°C response
V2
Temp (T)
response
V1
RF (dBm)
IN
P
P+10 dB
P +X
P
T
T
Figure 64. Graphical Representation of 10 dB Step Error Calculations
Figure 65 shows the typical 10 dB step error at 1900 MHz, where a dynamic range of 35 dB is obtained for E10dB
= ±1dB.
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2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-50
-40
-30
-20
-10
0
RF INPUT POWER (dBm)
Figure 65. 10 dB Step Error vs.
RF Input Power at 1900 MHz
Variation due to Modulation
RMS power detectors, such as the LMH2120 are inherently insensitive to different modulation schemes. This in
contrast to traditional detectors like peak detectors and LOG AMP detectors, where modulation forms with high
peak-to-average ratios (PAR) can cause significant output variation. This is because the measurement of these
detectors is not an actual RMS measurement and is therefore waveform dependent.
To be able to compare the various detector types on modulation sensitivity, the variation due to modulation
parameter is used. To calculate the variation due to modulation (EMOD), the measurement result for an
unmodulated RF carrier is subtracted from the measurement result for a modulated RF carrier. The calculations
are similar to those for variation over temperature. The variation due to modulation can be calculated by:
EMOD = (VOUT_MOD - VOUT_CW) / KSLOPE
(17)
where VOUT_MOD is the measured output voltage for an applied power level of a modulated signal, VOUT_CW is the
output voltage as a result of an applied un-modulated signal having the same power level.
Figure 66 shows the variation due to modulation for W-CDMA, where a EMOD of 0.16 dB is obtained for a
dynamic range from -34 dBm to -2 dBm.
1.5
1.0
0.5
0.0
W-CDMA, REL6
-0.5
W-CDMA, REL7
-1.0
-1.5
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 66. Variation due to Modulation for W-CDMA at 1900 MHz
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TEMPERATURE BEHAVIOR
The specified temperature range of the LMH2120 is from -40°C to 85°C. The RF detector is, to a certain extent
however, still functional outside these temperature limits. Figure 67, Figure 68, and Figure 69 show the detector
behavior for temperatures from -50°C up to 125°C in steps of 25°C. The LMH2120 is still very accurate within a
dynamic range from -35 dBm to 5 dBm. On the upper and lower end the curves deviate in a gradual way, the
lowest temperature on the bottom side and the highest temperature on top side.
10
125°C
In Steps of 25°C
1
0.1
-50°C
0.01
0.001
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 67. VOUT vs. RF Input Power at 1900 MHz
3
In Steps of 25°C
2
1
0
125°C
-1
-2
-3
-50°C
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 68. Linear Conformance Error vs. RF Input Power at 1900 MHz
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2.0
1.5
125°C
100°C
75°C
50°C
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
0°C
-25°C
-50
-40
-30
-20
-10
0
10
RF INPUT POWER (dBm)
Figure 69. Temperature Variation vs. RF Input Power at 1900 MHz
Layout Recommendations
As with any other RF device, careful attention must be paid to the board layout. If the board layout isn’t properly
designed, performance might be less than can be expected for the application.
The LMH2120 is designed to be used in RF applications, having a characteristic impedance of 50Ω. To achieve
this impedance, the input of the LMH2120 needs to be connected via a 50Ω transmission line. Transmission lines
can be created on PCBs using microstrip or (grounded) coplanar waveguide (GCPW) configurations.
In order to minimize injection of RF interference into the LMH2120 through the supply lines, the PCB traces for
VDD and GND should be minimized for RF signals. This can be done by placing a decoupling capacitor between
the VDD and GND. It should be placed as close as possible, to the VDD and GND pins of the LMH2120.
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REVISION HISTORY
Changes from Revision B (February 2013) to Revision C
Page
•
Changed layout of National Data Sheet to TI format .......................................................................................................... 28
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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)
LMH2120UM/NOPB
LMH2120UMX/NOPB
ACTIVE
ACTIVE
DSBGA
DSBGA
YFZ
YFZ
6
6
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
Level-1-260C-UNLIM
-40 to 85
-40 to 85
R
R
3000 RoHS & Green
SNAGCU
(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
5-Nov-2022
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
K0
P1
W
B0
Reel
Diameter
Cavity
A0
A0 Dimension designed to accommodate the component width
B0 Dimension designed to accommodate the component length
K0 Dimension designed to accommodate the component thickness
Overall width of the carrier tape
W
P1 Pitch between successive cavity centers
Reel Width (W1)
QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE
Sprocket Holes
Q1 Q2
Q3 Q4
Q1 Q2
Q3 Q4
User Direction of Feed
Pocket Quadrants
*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)
LMH2120UM/NOPB
LMH2120UMX/NOPB
DSBGA
DSBGA
YFZ
YFZ
6
6
250
178.0
178.0
8.4
8.4
0.89
0.89
1.3
1.3
0.56
0.56
4.0
4.0
8.0
8.0
Q1
Q1
3000
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
5-Nov-2022
TAPE AND REEL BOX DIMENSIONS
Width (mm)
H
W
L
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LMH2120UM/NOPB
LMH2120UMX/NOPB
DSBGA
DSBGA
YFZ
YFZ
6
6
250
208.0
208.0
191.0
191.0
35.0
35.0
3000
Pack Materials-Page 2
MECHANICAL DATA
YFZ0006x
D
0.425
±0.045
E
UMD06XXX (Rev B)
D: Max = 1.246 mm, Min =1.186 mm
E: Max = 0.846 mm, Min =0.786 mm
4215131/A
12/12
A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994.
B. This drawing is subject to change without notice.
NOTES:
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