A Q/Ku-K band MMIC double-balanced subharmonic diode ring mixer for satellite communications in GaAs pHEMT technology

摘要

A MMIC double-balanced subharmonic diode ring mixer was designed for broadband satellite communications exploiting a GaAs pHEMT process. The circuit implements the frequency conversion from Q (43.5-50 GHz) to Ku-K band (17-21.5 GHz). Besides the RF, LO, and IF baluns, the MMIC integrates a buffer amplifier for the local oscillator signal, which is designed between X and Ku bands (11-16.5 GHz), due to the subharmonic operation. The mixer measured conversion loss is between 8 and 12 dB along the bandwidth, with an LO power of 9 dBm. The input p1 dB and IP3 are 2 and 15 dBm, respectively. The balanced structure ensures an LO and 2 × LO leakages at the IF port lower than -25 and -35 dBm, respectively. Other spurious remain below - 67 dBc. The chip dimensions are 2.4 × 2.4 mm~2.