Zero-IF Second Harmonic SiGe Mixer with DC Offset Cancellation

In this work, a new SiGe mixer circuit topology operating with the second harmonically pumped mixing technique is proposed. The proposed circuit is developed for to be used in IC receivers which use Zero-IF mixers at their front ends. The Analysis of the circuit is performed and the appropriate operation conditions for second harmonically pumped mixing are investigated. The topology is quite suitable for the wide band applications and has a unique mechanism to prevent the LO to RF leakage which results in DC offset at the output. Simulations are performed and according to the simulation results, 21dB of conversion voltage gain is obtained within 2-12 GHz RF range while the DC voltage component at the output stays more than 80dB below the IF component.