A 50-GHz Low-Conversion-Loss Subharmonic Mixer Based on HISL Platform

This paper presents a 50-GHz low-conversion-loss subharmonic mixer based on the hybrid-integrated suspended line (HISL) platform. A novel three-wire-coupled filter is proposed, introducing a transmission zero at low frequencies, which improves the isolation between RF port and LO port. Additionally, a wideband low-pass filter based on LC structure is designed, leading to a significant enhancement in the circuit isolation. Compared with traditional subharmonic mixer structure, we add several additional transmission lines that, along with the stub, participate in the impedance matching of the anti-parallel diode pair (APDP) to reduce conversion loss. According to simulation results, the subharmonic mixer achieves the conversion loss of 5–8.5 dB, the optimal LO power is 7 dBm, indicating that low LO driving power is achieved.