Low noise Ku-band drain mixer using P-HEMT technology

A low-noise monolithic pseudomorphic HEMT drain mixer working in the Ku-band is reported. The RF frequency band is from 14 to 17 GHz with an IF fixed at 1 GHz. A drain mixer configuration has been chosen to inject LO and RF signals through different ports, improving the isolation between these ports. Another advantage of this topology is the lower noise figure compared to the gate mixers. A diplexer has been included to inject the LO signal and to extract the IF one. The circuit has been fabricated at the PML foundry using the D02AH process, which uses 0.2 μm gate length HEMTs. The chip size, including the diplexer and the RF matching network, is 1.5 mm². On-wafer measurements show a conversion gain over 2 dB for a RF signal of 16 GHz. The RF/LO isolation is better than 22 dB in the whole frequency band, thanks to the topology used. A SSB noise figure of 7.6 dB has been obtained, which is a good result for a monolithic Ku-band mixer