Low flicker-noise and low leakage direct conversion CMOS mixer for 5GHz application

This paper presents the design and measurement of low flicker-noise, high conversion gain double-balanced Gilbert cell mixer in CMOS process. Since the noise figure (NF) of the CMOS mixer is strongly affected by flicker noise (1/f noise), a dynamic current injection technique is used to reduce the flicker noise corner frequency. An inductor is employed to tune the tail capacitance in the local oscillator and the RF transconductance stages. So, it reduces the RF leakage through this parasitic capacitance. Moreover, output band elimination filter (BEF) is employed to suppress the leakage of the RF signal. The mixer is designed using TSMC 0.18 µm CMOS process. Simulations and measurements had been performed. The proposed mixer has a simulated conversion gain of 15dB and single side band noise figure is 10.6dB at 20kHz.