Performance evaluation of single-stage differential amplifier based on carbon nanotube

Abstract

The demand for power sensitive CMOS designs has grown significantly due to the fast growth of battery-operated portable applications. Design of low-power and high-performance submicron and deep submicron CMOS circuits has become a big challenge in nanoelectronics industries due to short-channel effect that occurs after scaling towards nanoscale devices. Silicon-based power transistor devices has low power consumption which allows more components per chip surface area. But silicon-based short-channel devices has generated DIBL effect, hot carriers’ effect and surface scattering, results in device performance degradation. To overcome these unwanted effects, carbon nanotube-based devices has shown the potential to replace silicon-based devices by sustaining the requirements of a high-speed nanodimensional devices because it has similar device operation with CMOS and produces lower leakage power than silicon-based devices. Differential amplifier circuit topology is applied in this research because it is a very useful operational amplifier circuit to examine the performance differences between carbon nanotube and conventional silicon when they are used as channel material by evaluating Common-Mode Rejection Ratio (CMRR) of differential amplifier. The objective of this research is to study the performance of Carbon Nanotube based differential amplifier based on CMRR and to compare the performance of Carbon Nanotube based differential amplifier with the silicon based differential amplifier. HSPICE tool is used in this research to simulate the differential amplifier circuit with current mirrors active load configuration to maintain the voltage gain for single-ended output, which is built using netlists of SPICE CNFET model and PTM model, respectively. From the research findings, the highest CMRR of CNFET-based differential amplifier with constant input DC offset voltages in differential mode and common mode is 72.68 dB. When input DC offset voltages in differential mode and common mode decreases, CNFET-based differential amplifier has achieved CMRR of 92.16 dB, which increases by 26.8% compared to that of constant input DC offset voltages. The CMRR of MOSFET-based differential amplifier (21.83 dB) is smaller than the CMRR of CNFET-based differential amplifier (132.02 dB), with a difference of 110.19 dB or 143.2%.