Threshold Inverter Quantizer (TIQ)-Based 2-Bit Comparator Using Spatial Wavefunction Switched (SWS) FET Inverters

Abstract

A Threshold Inverter Quantizer (TIQ)-based voltage comparator is used to quantize analog input signal in flash ADC designs. This quantizer is based on the systematic sizing of CMOS inverter thus eliminating resistor array which is used for conventional comparator array. Such an implementation removes static power during quantization of analog input signal. This paper presents a simulation of TIQ 2-bit-based comparator using spatial wavefunction switched (SWS) field effect transistor (FET)-based CMOS inverters. The inverters use 4-state SWSFETs. Unlike conventional FETs, SWSFETs consist of two or more vertical coupled arrays of either quantum dot or quantum well channels, where the spatial location of carriers within these channels is used to encode the logic states (00), (01), (10), and (11). The TIQ-based comparator circuit presented here is based on the 2-bit SWS-CMOS inverter. The schematic of the ADC comparator circuit is demonstrated as well as the 2-bit ADC configuration cascading two 2-bit SWSFET-based inverters in CMOS-X. The circuit simulation was done in Cadence and SWSFET was modeled by integrating Berkeley Short-Channel IGFET Model (BSIM) and the Analog Behavioral Model (ABM). The 2-bit comparator circuit provides a four-state logic output voltage for any given analog input signal.