A very wideband FET resistive MMIC double balanced mixer based on empirical non-linear cold FET model

Abstract

A broadband FET resistive mixer MMIC on GaAs substrate is described in this paper. A non-linear model of MESFET operating in passive mode (Vds=0V) developed for design and simulation of mixer has also been analyzed. Measured mixer results match closely with the simulations based on the developed model. The on-chip broadband spiral baluns delivered wide frequency range from 230 MHz to 1.8 GHz while the LO/RF frequency coverage was from 2-8 GHz. 10 dB conversion loss was achieved for 500 MHz IF at 5 GHz RF frequency, and 10 dBm LO power. The mixer exhibited >10 dBm input 1 dB compression point, 18 dBm input 3rd order intercept point and >30 dB LO-IF and RF-IF isolation. The mixer was realized in compact chip area of 2.8 × 2.6 mm2 through intensive EM simulations using ADS momentum EM simulator and was fabricated using the standard G7A MESFET process at GAETEC.