Optimum biasing and design of high performance double gate MOSFET RF mixers

The optimum biasing conditions and structural design parameters for novel nano-scale radio frequency mixers based on single double gate MOSFET is investigated. Our objective is to analyze and identify the correlation of the conversion gain of the mixer circuit with the signal conditions at the local oscillator 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. The most important figure of merit in the mixer performance 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 double gate MOSFETs (L_gate ≥ 3t_Si), L_gate 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 double gate MOSFETs is ultimately limited by the short channel effects perpetrated by any given structural constraint, an optimum body thickness tSi 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.