Design and analysis of a miniature W-band MMIC subharmonically pumped resistive mixer

A W-band monolithic sub-harmonically pumped (SHP) resistive mixer was designed and fabricated using a standard 0.15μm PHEMT process. A nonlinear model featuring modified drain-current characteristics was developed and used in circuit simulation. A small chip size of 1.5 × 1.0 mm² was achieved by using a transformer as a LO balun. Measured results of this circuit showed 14-18 dB conversion losses from 75 to 88 GHz, and agree well with simulation. Analysis on circuit imbalance shows that the phase imbalance of the balun is the dominant factor on LO isolation, and the conversion loss is quite robust to all circuit imbalances.