LMV221_14 Datasheet, PDF (1/41 Pages) Texas Instruments – 50 MHz to 3.5 GHz 40 dB Logarithmic Power Detector for CDMA and WCDMA

LMV221
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SNWS018B – DECEMBER 2006 – REVISED MARCH 2008
LMV221 50 MHz to 3.5 GHz 40 dB Logarithmic Power Detector for CDMA and WCDMA
Check for Samples: LMV221
FEATURES
1
•2 40 dB Linear in dB Power Detection Range
• Output Voltage Range 0.3 to 2V
• Shutdown
• Multi-Band Operation from 50 MHz to 3.5 GHz
• 0.5 dB Accurate Temperature Compensation
• External Configurable Output Filter Bandwidth
• 2.2 mm x 2.5 mm x 0.8 mm WSON 6 Package
APPLICATIONS
• UMTS/CDMA/WCDMA RF Power Control
• GSM/GPRS RF Power Control
• PA Modules
• IEEE 802.11b, g (WLAN)
DESCRIPTION
The LMV221 is a 40 dB RF power detector intended for use in CDMA and WCDMA applications. The device has
an RF frequency range from 50 MHz to 3.5 GHz. It provides an accurate temperature and supply compensated
output voltage that relates linearly to the RF input power in dBm. The circuit operates with a single supply from
2.7V to 3.3V.
The LMV221 has an RF power detection range from −45 dBm to −5 dBm and is ideally suited for direct use in
combination with a 30 dB directional coupler. Additional low-pass filtering of the output signal can be realized by
means of an external resistor and capacitor. Figure 1 shows a detector with an additional output low pass filter.
The filter frequency is set with R_S and C_S.
Figure 2 shows a detector with an additional feedback low pass filter. Resistor R_P is optional and will lower the
Trans impedance gain (R_TRANS). The filter frequency is set with C_P//C_TRANS and R_P//R_TRANS.
The device is active for Enable = 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.
The LMV221 power detector is offered in the small 2.2 mm x 2.5 mm x 0.8 mm WSON package.
Typical Application
RF
PA
COUPLER
ANTENNA
50:
V_DD
RF_IN
2
1
OUT ^RS
6
LMV221
EN _{4 3 5} REF
GND
+
C_S
ADC
-
Figure 1. LMV221 with output RC Low Pass Filter
RF
PA
COUPLER
ANTENNA
50:
V_DD
RF_IN
2
1
OUT
6
LMV221
R_P
C_P
EN
REF
43 5
GND
+
ADC
-
Figure 2. LMV221 with feedback (R)C Low Pass
Filter
1
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2
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 © 2006–2008, Texas Instruments Incorporated