Impacts of impedance mismatch on the performance of RF mixers

The impacts of impedance matching on the performance of a radio frequency (RF) front-end mixer are studied. A fully differential double balanced Gilbert cell mixer has been considered in this work. The matching requirements for the low noise amplifier (LNA) and local oscillator (LO) are investigated. A novel solution to use the LNA output capacitors as a matching network is presented. Effects of the layout resistive and capacitive parasitics on the mixer image rejection are highlighted. Creative methods to reduce the impact of the layout parasitic impedances are presented.