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Abstract-A small-signal amplifier with three identical MOSFETs in Darlington's topology is proposed and qualitatively analyzed perhaps for the first time. Unlike CS-MOSFET amplifiers, the voltage gain of the proposed circuit is found considerably higher than unity. This amplifier can be used to amplify audio range signal excursions swinging in 0.1-2mV range. In the narrow-band performance range, the proposed amplifier produces simultaneously high voltage and current gains with low harmonic distortion. These properties offer a flexible application range to the proposed circuit as high-voltage-narrow-band amplifier in permissible audiofrequency range. An additional biasing resistance RA is to be essentially used in the proposed circuit to maintain its voltage/current amplification property. Variations in voltage gain as a function of frequency and different biasing resistances, temperature dependency of performance parameters like voltage gain, bandwidth, current gain, input/output noises and total harmonic distortion of the amplifier are perused to provide a wide spectrum to the qualitative studies.Index Terms-Small signal RC coupled amplifiers, darlington amplifiers, common Source MOS amplifiers, triple darlington amplifiers, MOSFET darlington pairs.

New circuit models of 'Complementary-Symmetry Class-AB and Class-B Push-Pull Amplifiers' are proposed. The proposed Class-AB amplifier circuit, configured by matched Darlington pairs, possesses 62.83% efficiency with low harmonic distortion (0.94%). However the proposed Class-B amplifier that is configured by using Triple Darlington configuration of matched BJTs, produces improved efficiency (73.28%) on the cost of enhanced harmonic distortion (1.23%). The proposed circuit model of Class-B Amplifier is perhaps a fresh approach. Variation of efficiency and total harmonic distortion as a function of biasing resistances and temperature are also observed. Proposed power amplifier may be quite useful for transmitters and other analog communication circuits.

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