Development and Qualitative Analysis of a New Circuit Model of Two-Stage Small-Signal Sziklai Pair Amplifier

Abstract

New circuit model of a two-stage small-signal Sziklai pair amplifier is proposed for the first time. The proposed amplifier circuit, which is obtained by cascading a small-signal Sziklai pair amplifier (Stage-1) with triple-transistor based compound Sziklai amplifier (Stage-2), is analyzed on the qualitative scale. Performance of the proposed amplifier is compared with that of Stage-1 and Stage-2 amplifier circuits to provide a wide spectrum to the qualitative studies. Proposed amplifier uses three additional biasing resistances in its circuit configuration and crops high voltage gain (237.50), high current gain (339.98) with wider bandwidth (2MHz) in 1-15mV range of AC input at 1 KHz. The proposed circuit successfully removes the poor response problem of conventional Darlington pair amplifiers at higher frequencies and narrow bandwidth problem of recently developed (by authors) circuit of small-signal Sziklai pair amplifier. Variation in voltage gain as a function of frequency and different biasing resistances, bandwidth and harmonic distortion of the amplifier is also pursued. The proposed amplifier may be useful for those applications where high voltage and current gain would be the prime requirement of amplification in a wider frequency range, spanned approximately from 200Hz to 2.5MHz.