Low distortion FET oscillator with feedback loop for amplitude stabilization

Claim 1

An oscillator comprising, in combination: a field effect transistor having drain, source and gate electrodes; direct voltage means connected between said drain and a common reference; inductive-capacitive circuit means connected to the source and one of the other electrodes to provide output oscillations at the drain electrode at a selected frequency, said inductive-capacitive circuit means including a coil connected from the source to said common reference and a pair of capacitors connected in series between said one electrode and said reference, said source and one end of said coil being connected to the junction of said series capacitors; feedback loop means including a third capacitor, a unilateral conducting device having a cathode and an anode, and first resistance means serially connecting the drain electrode to the gate electrode to provide a gate control voltage inversely proportional to the drain output voltage amplitude, said loop further including means for adjusting the portion of the output voltage from said drain electrode coupled to said gate electrode through said loop; a fourth capacitor connected between said anode and common reference in parallel with said first resistance means; and a second resistance means connected from said cathode to said common reference; said feedback means, fourth capacitor and said second resistance means acting to control and maintain the amplitude level of said oscillations below a level causing limiting.