Bias optimization of 2.4 GHz double gate MOSFET RF mixer

Abstract

The optimum biasing points and structural design parameters for novel nano-scale double gate MOSFET (DG-MOSFET) radio frequency mixers are investigated at 2.4 GHz. Our objective is to analyze and identify the correlation of the conversion gain of the mixer circuit with the signal amplitude of the local oscillator (LO) as well as different device parameters, such as the gate length (L gate ), doping concentration (N A ) and body thickness (t Si ), thus minimizing signal loss and power consumption and increasing stability. The most important figure of merit is found to be the LO DC bias that determines the level of non-linearity in the transconductance response. Furthermore, we observe that in properly designed DG-MOSFETs $$(\hbox{L}_{gate} \ge 3t_{Si}),\; \hbox{L}_{gate}$$ ( L g a t e ? 3 t S i ) , L g a t e and N A have limited impact on the conversion gain of the mixer, while t Si has a more significant role to play. Although the mixing performance of DG-MOSFETs is ultimately limited by the short channel effects perpetrated by any given structural constraint, an optimum body thickness t Si exists in each case to maximize the conversion gain. Thus, we illustrate how 2D and quantum-corrected simulations can identify the optimum body thickness and optimum bias conditions in such compact nano-scale mixers.