A Low Power Highly Linear CMOS Current Mode Up-Conversion Mixer

Abstract

In order to decrease the power dissipation and supply voltage, a current mode up-conversion mixer for RF transmitter is proposed in this paper. Different from the traditional Gilbert structure, the mixer replaces the transconductance stage with current mirrors. This method can bring enough conversion gain and high linearity. The way of current bleeding is also adopted here to improve the performance. The simulation is made by Cadence Spectre in CHRT 0.18mm CMOS mixed signal/RF process. The simulation results indicate that the mixer achieves 24.5dBm third-order input intercept point (IIP3), 5dB conversion gain and 14.9dB SSB noise figure while its power dissipation is only 3.8mW under 1.2 V supply voltage. It is especially suitable for low power mobile communication.

An Analytical Model of Conversion Gain for Submicron Active Mixers with LO Offsets

“…In order to reduce noise contribution from mixers and its cascaded circuits to the front-end system noise, and compensate for the loss of the IF filter as well, the mixers with a conversion gain are highly preferred. Due to high conversion gain and superior port isolation, etc., active mixers (i.e., Gilbert mixers) have been widely used in current integrated RF front-end circuits [3][4][5]. Therefore it is undoubtedly significant to accurately analyze and predict the gain characteristics of active mixers.…”