The LMV221 is a 40 dB RF power detector intended for usein CDMA and WCDMA applications. The device has an RFfrequency range from 50 MHz to 3.5 GHz. It provides an accuratetemperature and supply compensated outputvoltagethat relates linearly LMV221SD/NOPB the RF input power in dBm. The circuitoperates with a single supply from 2.7V to 3.3V.
The LMV221 has an RF power detection range from −45 dBmto −5 dBm and is ideally suited for direct use in combinationwith a 30 dB directional coupler. Additional low-pass filteringof the output signal can be realized by means of anexternalresistor and capacitor. Figure (a) shows a LMV221SD/NOPB detector with anadditional output low pass filter. The filter frequency is set withRS and CS.
Figure (b) shows a detector with an additional feedback lowpass filter. Resistor RP is optional and will lower the Transimpedance gain (RTRANS). The filter frequency is set withCP//CTRANS and RP//RTRANS.
The device is active for Enable = High, otherwise it is in a lowpower consumption shutdown mode. To save power and preventdischarge of an external filter capacitance, the outpu (OUT) is high-impedance during shutdown.
The LMV221 powerLMV221SD/NOPB is offered in the small 2.2 mm x2.5 mm x 0.8 mm LLP package.
Features
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 LMV221SD/NOPB compensation
External configurable output filter bandwidth
2.2 mm x 2.5 mm x 0.8 mm LLP 6 package
Applications
UMTS/CDMA/WCDMA RF power control
GSM/GPRS RF power LMV221SD/NOPB control
PA modules
IEEE 802.11b, g (WLAN)
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