Design of a 60 GHz subharmonic mixer MMIC

The design of a subharmonically pumped (SHP), monolithic microwave integrated circuit (MMIC) mixer for future wireless communications applications is described. The mixer uses an anti-parallel diode pair to achieve frequency translation by mixing the RF signal with the second harmonic of the fundamental LO pump. The circuit was fabricated by Triquint Semiconductor Inc. using their GaAs MMIC PHEMT process. The overall chip size is 1.2 mm × 1.3 mm. Measured conversion loss is 13 dB with a 61 GHz RF input signal and RF port return loss is better than 10 dB over a 61.4 to 62.5 GHz frequency range. Simulation predicts a conversion loss of 13 dB over 59 to 61 GHz band and an RF port return loss of better than 10 dB over this range. The simulated 1-dB compression point occurs with an RF input power level of 5 dBm.