Programmable intermediate frequency RSSI system including an adjustable rectifying stage

摘要

An IF receiver system includes an IF signal path formed by an IF amplifier section, a bandpass filter, and a limiter section. An RSSI (Receive Signal Strength Indicator) circuit is coupled to the IF amplifier section and the limiter section and generates an RSSI output signal which varies linearly with logrithmic changes in input power. A storage unit is coupled to the RSSI circuit and is configured to store a value which controls current limiting associated with the RSSI circuit. In one specific implementation, the limiter section includes a plurality of serially coupled limiter stages. The RSSI circuit includes a plurality of rectifying stages, wherein a separate rectifying stage is coupled to an input of a corresponding limiter stage. An additional rectifying stage is coupled to an output of a last of the limiting stages. The value within the storage unit controls the extent of current limiting associated with the additional rectifying stage.