Example: JFETAMP
Single stage amplifier with N-channel JFET

System

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System excitation

The circuit is stimulated by a single-phase power source with amplitude 1V and a frequency 1kHz.

Task

  1. Obtain the direct current analysis and determine the quiescent operating point. Use the transistor model type 2N3458 (Fairchild Semiconductors).
  2. Display the transient analysis for two periods of Vin and Vout, the voltage across Rz.
  3. Compute the frequency characteristics of the voltage transfer function with and without the blocking capacitor C3. Determine the amplification factor for f = 1kHz and the frequency range of the amplifier for the 3dB drop.
  4. Obtain the Fourier analysis of the output signal Vout. Set Vs = 0.5V and obtain Fourier and transient analysis. Set Vs = 2V and display both kinds of analysis again.

Assumptions

JFETN1 model of JFE transistor can be used for T1.

Last Update

August 13, 2007