A 1.2V wideband CMOS mixer with high conversion gain and low flicker noise

This paper presents the design of a wideband CMOS mixer (frequency convertor) for direct-conversion receivers. The mixer consists of a transconductance stage, a passive switching stage and a current amplifier. The current amplifier with gm-boosted structure realizes a low input resistance. It absorbs the down-converted IF current at the output node of the switching pair and amplifies it through a current mirror. The low noise characteristic of the current amplifier helps to improve the noise performance of the proposed mixer. In order to improve the power efficiency, current-reusing technique is adopted in the transconductance stage. The proposed mixer is designed in 0.13μm RFCMOS process. Simulation results show a 20dB conversion gain, a 10dB SSB noise figure and a 4.5 dBm IIP3 over the wideband operation frequency band from 1GHz to 3GHz while dissipating 2.5mA under a 1.2V supply voltage.