A Low Flicker Noise CMOS Mixer Using Two Resonating Inductors for Direct Conversion Receivers

This paper presents the design, implementation, and measurement of a novel low flicker noise RF mixer in a 0.18 mum CMOS process for C-band direct conversion receivers. The low flicker noise mixer is implemented by incorporating a double-balanced Gilbert-type configuration, the RF leakage-less current bleeding technique, and Cp resonating technique. By using two separate inductors at the node between the current bleeding devices and LO switches, conversion gain and flicker noise performance are significantly improved. Also, a double-balanced Gilbert-type mixer with current bleeding circuits without inductors is fabricated and measured for analysis and comparison purposes. The proposed mixer has a measured conversion gain of 16.1 dB, a measured IIP3 of -5 dBm, a measured noise figure of 9.8 dB at 1 MHz, and a flicker corner frequency of 125 kHz while consuming only 7mW of DC power. To the best of our knowledge, the proposed mixer shows the lowest flicker corner frequency (125 kHz) with a more than 15 dB of conversion gain in CMOS process