Design of Subharmonic Mixers above 100 GHz

This paper presents the design and simulation of several fixed-tuned sub-harmonic mixers cover frequencies from 110 GH to 130 GHz, 215 GH to 235 GHz, 310 GH to 350 GHz, and 400 GH to 440 GHz. Among them, 120 GHz, 225 GHz, 330 GHz subharmonic mixers are designed with flip-chipped planar schottky diode mounted onto a suspended quartz-based substrate, the 225 GHz and 425 GHz subharmonic mixers are GaAs membrane integrated, and the 115 GHz subharmonic mixer has been fabricated and tested already.

Millimeter-wave fixed-tuned subharmonic mixers with planar Schottky diodes

Two different frequency bandwidth subharmonic mixers（SHM） using planar Schottky mixing diodes are discussed and fabricated.Full-wave analysis is carried out to find the optimum diode embedding impedances with a lumped port for modeling the nonlinear junction.The SHM circuit is divided into several different parts and each part is optimized using the calculated diode impedances.The divided parts are then combined and optimized together.The exported S-parameter files of the global circuit are used for conversion loss（CL） discussion.For the 150 GHz SHM,the lowest measured CL is 10.7 dB at 153 GHz,and typical CL is 12.5 dB in the frequency range of 135-165 GHz.The lowest measured CL of the 180 GHz SHM is 5.8 dB at 240 GHz,and typical CL is 13.5 dB and 11.5 dB in the frequency range of 165-200 GHz and 210-240 GHz,respectively.

Design of Ka-band antipodal finline mixer and detector

This paper mainly discusses the analysis and design of a finline single-ended mixer and detector. In the circuit, for the purpose of eliminating high-order resonant modes and improving transition loss, metallic via holes are implemented along the mounting edge of the substrate embedded in the split-block of the WG-finline-microstrip transition. Meanwhile, a Ka band slow-wave and bandstop filter, which represents a reactive termination, is designed for the utilization of idle frequencies and operation frequencies energy. Full-wave analysis is carded out to optimize the input matching network of the mixer and the detector circuit using lumped elements to model the nonlinear diode. The exported S-matrix of the optimized circuit is used for conversion loss and voltage sensitivity analysis. The lowest measured conversion loss is 3.52 dB at 32.2 GHz; the conversion loss is flat and less than 5.68 dB in the frequency band of 29-34 GHz. The highest measured zero-bias voltage sensitivity is 1450 mV/mW at 38.6 GHz, and the sensitivity is better than 1000 mV/mW in the frequency band of 38-40 GHz.

A millimeter-wave monolithic doubly balanced diode mixer

A broadband miniature doubly balanced diode mixer chip fabricated by Win＇s 0.15/zm pHEMT technology is presented. In order to save chip area, a four-fold modified Marchand balun is used. A coupled line U section improves the port to port isolation and provides the IF-output port. The mixer achieves a low conversion loss of 5.5 to 10.7 dB and high isolation of more than 26 dB over a 26-40 GHz RF/LO bandwidth and a DC-14 GHz IF bandwidth. The mixer＇s chip size is around 0.96 mm2.

A novel circuit architecture for fourth subharmonic mixers

A circuit topology for high-order subharmonic（SH） mixers is described.By phase cancellation of idle frequency components,the SH mixer circuit can eliminate the complicated design procedure of idle frequency circuits.Similarly,the SH mixer circuit can achieve a high port isolation by phase cancellation of the leakage LO, RF and idle frequency signals.Based on the high-order SH mixer architecture,a new Ka-band fourth SH mixer is analyzed and designed,it shows the lowest measured conversion loss of 8.3 dB at 38.4 GHz and the loss is lower than 10.3 dB in 34-39 GHz.Measured LO-IF,RF-LO,RF-IF port isolation are better than 30.7 dB,22.9dB and 46.5 dB,respectively.