128-jfet-colpitts-oscillator-simulation

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JFET Colpitts oscillator realized with N-channel JFET is given in figure bellow.
Simulate JFET Colpitts oscillator.

jfet-colpitts-oscillator

JFET Colpitts oscillator is similar with JFET Hartley Oscillator, but for Colpitts oscillator, excitation for active amplifier comes originally from capacitor voltage divider. In modified scheme given above, L-C resonant circuit is made of one inductor and two capacitors. JFET has good feature for application in Colpitts oscillator since it has high input impedance that not burdening L-C resonant circuit and have good high frequency characteristic. In the drain branch of JFET there is dimmer inductance LP that obtains small damping of L-C circuit i.e. increases quality factor Q as well as output impedance. Oscillation frequency of JFET Colpitts oscillator is:

jfet_colp_os_eq1

Coupling capacitors CS1 and CS2 has to have much higher capacitance then C1 and C2.

Simulate JFET Colpitts oscillator.

External Links:

JFET Colpitts oscillator on Wikipedia
JFET Colpitts oscillator on Hyperphysics
JFET Colpitts oscillator on Electronics-Tutorials

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