A New Circuit Model of Small-Signal Amplifier using JFETs in Darlington pair Configuration
|Dr. SachchidaNand Shukla1 and Susmrita Srivastava2
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A small-signal amplifier with two identical JFETs in Darlington pair is proposed and qualitatively analyzed perhaps for the first time. Unlike CS-JFET amplifiers, the voltage gain of this amplifier is significantly higher than unity. In addition, this amplifier can also be tuned in the specific range of audible frequency extended from 90Hz to 19KHz. Tuning performance makes this amplifier suitable to use in Radio and TV receivers. An additional biasing resistance RA, ranging in 3KΩ to 1MΩ, is to be essentially used in the proposed circuit to maintain its voltage/current amplification property. With this additional biasing resistance, the proposed amplifier crops considerably wide bandwidth (12.365MHz), significantly high current gain (530.909) and fairly high voltage gain (9.108) in 1-80mV input signal range at 1 KHz frequency. These properties offer a flexible application range to the proposed amplifier as high power gain, wide band, or tuned amplifier in permissible audio-frequency range. Variations in voltage gain as a function of frequency and different biasing resistances, temperature dependency of performance parameters, bandwidth and total harmonic distortion of the amplifier are also perused to provide a wide spectrum to the qualitative studies.