A Hybrid Transformer-Based CMOS Duplexer With a Single-Ended Notch-Filtered LNA for Highly Integrated Tunable RF Front-Ends

A hybrid transformer-based CMOS tunable duplexer with a single-ended blocker-tolerant low-noise amplifier (LNA) is proposed for a highly integrated reconfigurable RF front-end architecture. The proposed LNA adopts Q-enhanced LC notch filter at the source of the cascode device and LC bandpass filter at the load. It improves the blocker tolerance and linearity of the receiver by rejecting unwanted out-of-band blockers and transmitter (TX) leakage signals. The duplexer with the notch-filtered LNA was fabricated in a 65-nm CMOS process. It has a voltage gain of 24.2 dB from the antenna to the LNA output with 28-dB notch filtering, cascaded noise figure of 6.4 dB, TX insertion loss of 3.8 dB, and IIP3FD of 52.4 dBm. It can also cover a mid-band range from 1.6 to 2.2 GHz in cellular applications. It draws an average current of 8 mA from a supply voltage of 1.2 V and has an active area of 1.19 mm².