Design and optimization of sub harmonic mixer with harmonic rejection for direct-down conversion receivers

Frequency translation in a system is performed by a non-linear device known as a mixer. There are various topographies from simple single ended, single balanced mixers to more complicated double & triple balanced mixers that provide better isolation from the Local Oscillator (LO) and spurious. The most popular double-balanced mixer used in RFIC designs is the Gilbert Cell mixer. The design of this mixer with harmonic rejection is the subject of this paper. This paper presents a novel low power high linear sub-harmonic mixer for direct-down conversion receivers, which is proposed to improve the linearity and enhance the gain of the Mixer and also avoids the need for a discrete filter by attenuating the third and fifth harmonics using the harmonic rejection structure. Simulation results performed by Advanced Design System (ADS) shows a voltage conversion gain of 10.119 dB, an overall double side band noise figure of 6.219 dB, and IIP3 of 8.018 dBm from 2.8 V supply for a frequency of 2500 MHz.