A 50–62 GHz compact subharmonic passive mixer MMIC with low conversion loss

This paper presents a compact 50–62 GHz monolithic passive subharmonic pumped resistive mixer (SHPRM) using a 0.15-μm GaAs pHEMT foundry process. The proposed mixer requires only a half of the LO frequency compared to a fundamentally pumped and is designed in a resistive structure advantages for no drain bias and low DC currents. The mixer includes an IF filter and a scale-down marchand balun with capacitance load. To reduce conversion loss, a quarter-wavelength shorted stub at LO frequency is in parallel with LO input line, it appearing as an open circuit to the LO frequency and also provide the return paths for the RF signals. This mixer achieve a down-conversion loss of 6.55 ± 1 dB when fix LO frequency at 25 GHz and RF frequencies range 50–58 GHz, a down-conversion loss of 4.6 ± 0.6 dB when fix LO frequency at 28 GHz and RF frequencies range 56–62 GHz. In addition, the proposed mixer exhibits more than 18 dB and 30 dB of isolation for the second harmonic of the LO signal at the radio frequency (RF) ports and at the intermediate frequency (IF) ports, respectively. The chip size is 0.85 × 1.41 mm2 only. The total dc power consumption is ∼ 0mW.