A Low-Power Multiband Blocker-Tolerant Receiver With a Steep Filtering Slope Using an N-Path LNA With Feedforward OB Blocker Cancellation and Filtering-by-Aliasing Baseband Amplifiers

Abstract

This paper describes a low-power multiband blocker-tolerant receiver (RX) with three steps of filtering among two transconductance (Gm) stages. To consistently achieve low noise figure (NF) and high linearity over a wide range of operating frequency, a single-Gm low-noise amplifier (LNA) heads the RX with embedded N-path filtering, and feed-forward out-of-band (OB) blocker cancellation to surmount the tradeoff between the passband bandwidth (BW) and OB rejection without sacrificing the power budget. A filtering-by-aliasing (FA) block embeds another single-Gm baseband (BB) amplifier to allow a steep roll-off lowpass response with a clock-rate-defined passband BW. Prototyped in 28-nm CMOS, the RX achieves a 3.1-dB NF and a 5.4-dBm OB-IIP3 at 2 GHz, while consuming only 22 mW, measured at a gain of 22 dB. The tunable passband BW is 2.5 to 20 MHz, and the RF-to-BB composite filtering slope is 20 to 50 dB/10 MHz at 1.75xBW offset. The RX occupies a 0.24 mm² active area.