A Harmonic-Rejecting CMOS LNA for Broadband Radios

The local oscillator harmonics corrupt the desired signal in broadband RF receivers by downconverting interferers. This paper proposes the notion of harmonic rejection in the front-end low-noise amplifier so as to relax the stringent matching required of harmonic-reject mixers. Described are frequency response shaping techniques by feedforward and unilateral Miller capacitance multiplication for a signal bandwidth of 100 MHz to 10 GHz. A calibration algorithm is also proposed for the tuning of the frequency response. An experimental prototype fabricated in 65-nm digital CMOS technology provides at least 20 dB of rejection while consuming 8.64 mW with a 1.2-V supply.