High performance Q-band subharmonic receiver chip set

A high conversion gain receiver chip set for Q-band millimeter-wave wireless communication systems is designed and fabricated by using 0.1 μm GaAs-based pseudomorphic high electron mobility transistors (PHEMTs) and the coplanar waveguide (CPW) library. The fabricated receiver chip set consists of a subharmonic mixer circuit and a low noise amplifier. From the device characterization, the subharmonic mixer shows a maximum conversion gain of ∼4.8 dB at an RF frequency of 40 GHz for a local oscillation (LO) power of 10 dBm at 17.5 GHz. The subharmonic mixer also exhibits a high degree of isolation characteristic of -35.8 dB for LO-to-IF and -40.5 dB for LO-to-RF, respectively, at a LO frequency of 17.5 GHz. The low noise amplifier shows a S₂₁ gain of ∼25.6 dB at a RF frequency of 40 GHz. Due to the high performances of the circuits, the fabricated receiver chip set produces a high conversion gain of 30.4 dB for the Q-band application purpose.