Sziklai Pair based Small signal Amplifier with bjt-mosfet Hybrid Unit at 180nm Technology

Abstract

Two circuit models of Small Signal amplifier, constituted with BJT-MOSFET hybrid unit under Sziklai pair topology are designed and analyzed using ‘PSpice’ and ‘Cadence Virtuoso and Spectre simulation tool (at GPDK 180nm technology)’ respectively. First amplifier (Circuit-1) uses PSpice user-defined model of BJT and MOSFET whereas the second amplifier (Circuit-2) consists of transistors available at GPDK 180nm technology. Circuit-1 can amplify the AC signals of 1mV-1nV range with optimum voltage gain 389.532, 137.570 current gain, 14.464MHz bandwidth and 2.43% THD. However, Circuit-2 can amplify AC signals of 0.1mV-10nV range with 164.018 voltage gain, 32.775 current gain, 11.906 MHz bandwidth, and 13.608E-6% THD. Both the proposed amplifier circuits remove narrow band problem and generate better results than earlier announced small signal Sziklai pair amplifier with BJT-MOSFET hybrid unit in respect of voltage and current gains, bandwidth, THD, and power consumption. Proposed amplifiers successfully address the problem of poor frequency response of small signal Darlington pair amplifier in higher frequency range and narrow bandwidth limitations of small-signal PNP Sziklai pair amplifier. Dependency of the proposed amplifiers at various biasing resistances and performance with temperature variation, noise variation, DC supply variation, and phase variation are also discussed herein. Proposed Circuits display strong dependency over ideal maximum forward beta ‘β’ of NPN transistor, Transconductance ‘VTO’ of P-MOS transistor and additional biasing resistances ‘RA’. Layout of Circuit-2 is found to cover 96.3898µm2 area with 11.32µm length and 8.515µm breadth. Minor percentage variation between pre-layout and post-layout simulation results of Circuit-2 validates the proposed design at GPDK 180nm technology. Monte Carlo and Process Corner analysis are also performed to test the robustness and insensitivity of Circuit-2 against mean value of the parameters and process and mismatch respectively. Performance summary of the proposed circuits and comparison with the recently reported designs shows effectiveness of the proposed circuits in terms of power gain, THD, voltage gain, current gain, input referred noise and power gain. Qualitative analysis of the proposed Circuits recommends its usability as Low Noise Amplifier in the portable RF noise measurement system.