1/f noise optimum for field-effect transistors in single-ended resistive mixers

The low-frequency noise in single-ended resistive FET mixers is investigated with respect to the influence of the gate-source voltage. Using a simple broadband mixer with a Fujitsu HEMT, measurement and simulation results are compared yielding good agreement. Two mechanisms exists that create 1/f-noise: The self-mixing process and the self-mixing current. Both cancel each other, i.e., there is a gate bias where a flicker noise minimum appears. The location of this minimum can be controlled with the DC output impedance.