LTC5531 UUWUAPPLICATIO S I FOR ATIOApplications data (or audio) output and DC-coupled RSSI output for signal strength measurements and AGC. The LTC5531 can be used as a self-standing signal strength measuring receiver for a wide range of input signals from The LTC5531 can be used for RF power detection and –32dBm to 10dBm for frequencies from 300MHz to 7GHz. control. Figure 1 is an example of transmitter power control, using the LTC5531 with a capacitive tap to the Operation at higher frequencies is achievable. Consult power amplifier. A 0.5pF capacitor (C1) followed by a factory for more information. 200Ω resistor (R1) forms a coupling circuit with about The LTC5531 can be used as a demodulator for AM and 20dB loss at 900MHz referenced to the LTC5531 RF input ASK modulated signals with data rates up to 2MHz. pin. In the actual product implementation, component Depending on specific application needs, the RSSI output values for the capacitive tap may be different depending on can be split between two branches, providing AC-coupled parts placement, PCB parasitics and parameters of the antenna. R1 C1 200Ω Tx PA 0.5pF 0.1µF Li-Ion 1% LTC5531ES6 MODULE ±0.05pF 1 6 CELL BAND RFIN VCC DIPLEXER 2 5 GND VOUT 3 4 OFFSET PCS BAND SHDN V DISABLE ENABLE OS ADJUSTMENT MOBILE PHONE VPC DSP BSE 5532 F01 Figure 1. Mobile Phone Tx Power Control Application with a Capacitive Tap 5531f 10
