A 0.4–6-GHz 17-dBm B1dB 36-dBm IIP3 Channel-Selecting Low-Noise Amplifier for SAW-Less 3G/4G FDD Diversity Receivers

A channel-selecting low-noise amplifier (CS-LNA) with blocker filtering is presented for a SAW-less diversity path receiver (RX) in frequency-division duplexing cellular systems. A hybrid N-path bandpass filter/band-reject filter (BPF/BRF) feedback network is applied to the LNA to create close-in reject bands around the passband to suppress transmit leakage and improve the out-of-band (OOB) input-referred third-order intercept point (IIP3). Control of the frequency and depth of the reject bands is demonstrated with analysis and simulation. A g
_m2
-g
_m3
cancellation linearization is applied to improve the in-band (IB) linearity. Adaptive LO swing and silicon-on-insulator (SOI) thick-oxide devices are demonstrated to improve the power-handling capability. The proposed CS-LNA is implemented in 32-nm CMOS SOI and operates from 0.4 to 6 GHz with the maximum rejection larger than 60 dB and power-handling capability up to 17 dBm. The prototype demonstrates an OOB IIP3 of 36 dBm and IB IIP3 of 10 dBm at 1 GHz. To the authors' knowledge, this is the highest blocker rejection, power-handling capability, linearity, and the widest tuning range for an LNA with tunable filtering.