CMOS Channel-Selection Low-Noise Amplifier With High- $Q$ RF Band-Pass/Band-Rejection Filter for Highly Integrated RF Front-Ends

In this letter, a CMOS tunable channel-selection low-noise amplifier (LNA) employing a high-${Q}$ RF band-pass (BP)/band-rejection (BR) filter is proposed for highly integrated RF front-ends in cellular applications. The proposed LNA implements a high-${Q}$ RF BP/BR filter characteristic based on a four-path filter theory from a baseband polyphase filter and a low-pass filter. It also provides a high rejection ratio for close-in transmitter leakage signal and out-of-band blockers. Therefore, it compensates for the limited filtering performance of the CMOS duplexer and improves the blocker-tolerance and linearity of the receiver. The proposed LNA is implemented in 65-nm CMOS technology. It achieves a maximum voltage gain of 20.4 dB, a minimum NF of 3.24 dB, and a notch rejection ratio of more than 56.4 dB. It can also cover a low-band and a mid-band from 0.7 up to 2.2 GHz in cellular applications. It draws an average current of 13 mA from a supply voltage of 1.2 V and has an active area of 0.62 mm
²
.