Fuqun Zhong

A Broadband W-band Subharmonic Mixers Circuit Based on Planar Schottky Diodes

A balanced sub-harmonic fix-tuned mixer is designed precisely based on combination of linear/nonlinear circuit simulation. The influence of parasitic parameter on the performance of the mixer is studied by building three dimensional electromagnetic model of antiparallel GaAs Schottky diode. The mixer is realized based on rogers substrate process to minimize the cost and simplify the assembly. The mixer works in the 82-104 GHz band with a simulated conversion loss less than 7.3 dB when pumped with 3.6mW of local oscillator power.

The design of a 310–350-GHz sub-harmonic mixer with planar schottky diodes

This paper presents the design and simulation of a novel fixed-tuned 310–350-GHz wide-band sub-harmonic mixer. The mixer is based on an anti-parallel pair of GaAs Schottky diodes fabricated at European company. The circuits are fully integrated with the RF/IF filter and flip-chipped onto a suspended quartz-based substrate. A best double-sideband-mixer loss of 5.7dB was achieved with 5mW of LO power at 332GHz. Over an RF band of 310350GHz, the double-sideband loss is below 11dB. This state-of-the-art optimization is attributed to lower parasitic devices and a low-loss waveguide circuit.

Optimization and design of a suspended 215–235-GHz subharmonically pumped mixer for space-borne radiometers

This paper presents the optimization and design of a low-loss fixed-tuned 215–235-GHz sub-harmonic mixer, pumped by planar GaAs Schottky diodes fabricated by European company for space-borne radiometers. The circuits are fully integrated with the RF/IF filter and flip-chipped onto a suspended quartz-based substrate. The GaAs Gunn oscillator is used as the local-oscillator (LO) and this paper also found an innovative nonlinear circuit model for GaAs Gunn diode in oscillator based on the physical mechanism. Its equivalent nonlinear circuit can assist the design of the Gunn LO. A best double-sideband-mixer loss of 6.4dB was achieved with 7mW of LO power at 224GHz. Over an RF band of 215–235GHz, the doublesideband loss is below 12dB. This state-of-the-art optimization is attributed to lower parasitic devices and a low-loss waveguide circuit.

Design of improved CMRC structure used in terahertz subharmonic pumped mixer

This paper presents a new improved compact, low-insertion loss, sharp-rejection, and easy to manufacture compact microstrip resonant cell (CMRC) structure [1] as microstrip or suspended-substrate microstrip lowpass filter (LPF) used in terahertz (THz) Subharmonically pumped mixer (SHM). In comparison to traditional high/low step-impedance filter used in SHM, this improved CMRC structure could shorten the circuit size by 50% and have advantages of better frequency selectivity property, as well as sideband rejection. By using suspended-microstrip transmission line structure, this improved CMRC structure improved its operation frequency up to THz. In addition, this improved structure also easy to manufacture through conventional lithography corrosion microstrip line technology. This improved CMRC structures circuit topology structure, equivalent-circuit model and full wave electromagnetic field simulation results and the SHM circuit topology model using improved CMRC structure are given.

110GHz high performanced varistor tripler

A 110GHz Schottky diode frequency tripler made with four barrier diodes by two DBES105a diodes from United Monolithic Semiconductor (UMS) company is presented. The circuit is design on a suspended quartz. The whole frequency tripler circuit is optimized by harmonic balance analysis simulator of ADS. The measured multiplication output power reaches 5mW and the efficiency is nearly 3% from 106GHz to 114GHz.