A double-balanced subharmonic passive mixer with an integrated quadrature local oscillator in 0.18 μm CMOS

This letter presents a double-balanced subharmonic passive mixer designed in a 0.18 μm CMOS technology.The biasing condition of the passive mixer is analyzed to optimize its conversion loss and local oscillator (LO) to RF/IF leakage performances. The four phases required for the mixer were generated using an on-chip LO and a divide-by-two circuit. The mixer converts an RF signal ranging from 3.5 to 6.7 GHz to an IF signal using an LO of 2.5 GHz with a voltage conversion loss of 7.2 ± 1.5 dB. The measured 1 × LO and 2 × LO leakages to the RF/IF port are -25/-60 dBm and -35/-65 dBm, respectively. The measured input third-order intercept point (IIP3) of the mixer is -2 dBm. The circuit operates from a 1.8 V supply and consumes 45 mW of power.