An Experimental Evaluation of X-Band Mixers using Dual-Gate GaAs Mesfets

Experimental results are presented for X-band GaAs MESFET mixers using a dual-gate device. This device combines high conversion gain and low noise operation with the convenient feature that the RF and local oscillator signals can be applied to the separate gates. Biased near pinch off a one micron gate MESFET in a 'disc' tuned circuit has yielded 11 dB of conversion gain and 6.5 dB noise figure (DSB) at 10 GHz with an IF of 30 MHz. Using an IF of 150 MHz a noise figure of 5.2 dB with 8 dB of conversion gain has been obtained.