A High-Performance 330-GHz Subharmonic Mixer Using Schottky Diodes

Abstract

This letter presents the design of a state-of-the-art 330-GHz subharmonic mixer (SHM) using planar Schottky diodes. Unlike conventional mixers, the embedded impedances of the diode chip are accurately extracted and then used for direct synthesis of the diode's peripheral circuit to efficiently design SHMs with good performance. Band-stop filters (BSFs) using symmetrical open stubs are adopted to recycle RF and local oscillator (LO) energy while simplifying the circuit. At room temperature, the mixer exhibits a single sideband (SSB) conversion loss (CL) of less than 10 dB from 292 to 356 GHz, with 3 mW of LO power at 164.5 GHz. A minimum SSB CL of 7.5 dB is achieved at 334 GHz. The measured return losses at RF and IF ports are typically better than 14 dB.