A 2.4GHz 1.8-V CMOS Sub-Harmonic Mixer with Inherent Harmonic-Rejection

This paper presents a novel low power high linear sub-harmonic mixer for direct-down conversion receivers, in which an inductive connection between RF and LO stages is proposed to improve the linearity and enhance the gain of Mixer. This is a novel mixer that not only frequency translates the RF signal to baseband directly but also avoids the need for a discrete filter by attenuating the third and fifth harmonics using the harmonic rejection structure. The proposed core uses 1/2 x LO generation scheme to overcome LO self-mixing and IMD2 related problems common in conventional Direct Conversion Receivers. Simulation results performed by Advanced Design System (ADS) in 0.18 mu m TSMC CMOS process show a voltage conversion gain of 15.57dB, an overall double side band noise figure of 6.88dB, input referred 1dB compression point of -11.5dBm and IIP3 of 1.5dBm while draining 4.2mA from 1.8V supply.