A SAW-less receiver front-end with continuously variable bandwidth and enhanced blocker-filtering

Abstract

A SAW-less receiver front-end with an active adjustable feedback loop for blocker-filtering is presented. By simply tuning the gain of loop amplifier, the −3 dB intermediate frequency (IF) bandwidth can be configured from 1 to 15 MHz continuously only using 46 pF capacitors. Moreover, the blocker current at low-noise amplifier (LNA) output can be effectively absorbed by the auxiliary capacitor and the loop amplifier buffer. The front-end operates from 0.1 to 2.5 GHz with maximal out-of-band rejection of 38 dB at 100 MHz offset frequency and it achieves 7-dBm out-of-band input third intercept point (IIP3). The design is implemented in 0.13 µm BiCMOS process.