A bias-shared direct downconversion receiver front-end with flicker noise minimization

A direct downconversion receiver front-end that employs current-mode passive mixers is described. Bias-sharing is employed between the RF transconductor and a baseband transimpedance amplifier (TIA). Flicker noise of the RF transconductor is mitigated by chopping the RF signal, which is made possible by employing phase-domain orthogonality between RF and baseband signals. A noise shaping network that suppresses the TIA thermal noise from around the frequency of the local oscillator is investigated. Simulations in a 0.13μm CMOS process show 35 dB conversion gain, 4.9 dB NF, and in-band 1dB compression point of -26 dBm. The noise reduction techniques improve the flicker noise corner from 1 MHz to 11 kHz, and the noise figure beyond the flicker corner from 5.8 dB to 4.9 dB. The design consumes 3.8 mA from 1.2 V supply.