Dual-gate mos-fet oscillator circuit with amplitude stabilization

Claim 2

An oscillator comprising, a dual-gate MOS field-effect transistor having a drain, source and two gate electrodes, means to couple a voltage source having a pair of terminals between said drain and source electrodes to provide a current conductive path controlled by said gate electrodes, a feedback path completed from said source electrode to one of said gate electrodes to operate said transistor in an oscillator circuit, a rectifying network time constant circuit connected in said feedback path to provide to said one gate electrode a unidirectional bias whose average value varies according to changes in the magnitude of signals appearing over said feedback path in a direction to reduce said changes, said means to couple said source electrode to a terminal of said voltage source including a resistor across which a second bias voltage is derived having a value determined according to changes in the level of current conductivity of said transistor which effectively alters said feedback signals in a direction to cancel said changes in the level of current conductivity of said transistor, means to apply a third bias to said second gate electrode to cause the control exercised on said conducting path by said second gate electrode to be determined by the level of conductivity of said transistor in response to said feedback signal and said first bias applied to said first gate electrode so that the gain of said transistor is increased over that obtained in the absence of said second gate electrode and the application of said third bias thereof.

Claim 3

An oscillator as claimed in claim 1 and wherein said last mentioned means includes a resistive divider connected between the terminals of said voltage source to apply a fixed bias to said second gate electrode.

Claim 4

A field-effect transistor oscillator, including amplitude stabilization means, comprising: a MOS field-effect transistor having a drain, a source and first and second control gate electrodes; means for coupling a voltage source having a pair of terminals between said drain and source electrodes to provide a current conductive path controlled by said gate electrodes; a feedback path including a tank circuit for applying feedback signalS from said source electrode to said first gate electrode to operate said transistor in an oscillator circuit, said tank circuit having an adjustable reactance means whose value determines the frequency of oscillation of said oscillator circuit over a predetermined range of frequencies; a rectifying network time constant circuit connected in said feedback path to provide to said first gate electrode a unidirectional bias whose average value varies according to changes in the magnitude of signals appearing over said feedback path in a direction to reduce said changes; said means for coupling said source electrode to a terminal of said voltage source including a resistor across which a second bias voltage is derived whose value changes according to changes in the level of current conductivity of said transistor to effectively alter said feedback signals in a direction to oppose said changes in the level of current conductivity of said transistor; and means including a resistive divider connected between the terminals of said voltage source to apply a fixed bias to said second gate electrode, said last mentioned means including a capacitive impedance coupled between said second gate electrode and a terminal of said voltage source, whereby the control exercised on said conductive path by said second gate electrode is determined by the level of conductivity of said transistor.

Claim 5

A field-effect transistor oscillator, including amplitude stabilization means, comprising: a MOS field-effect transistor having a drain, a source and first and second control gate electrodes; means for coupling a voltage source having a pair of terminals between said drain and source electrodes to provide a current conductive path controlled by said gate electrodes; a feedback path including a tank circuit for applying feedback signalS from said source electrode to said first gate electrode to operate said transistor in an oscillator circuit, said tank circuit having an adjustable reactance means whose value determines the frequency of oscillation of said oscillator circuit over a predetermined range of frequencies; a rectifying network time constant circuit connected in said feedback path to provide to said first gate electrode a unidirectional bias whose average value varies according to changes in the magnitude of signals appearing over said feedback path in a direction to reduce said changes; said means for coupling said source electrode to a terminal of said voltage source including a resistor across which a second bias voltage is derived whose value changes according to changes in the level of current conductivity of said transistor to effectively alter said feedback signals in a direction to oppose said changes in the level of current conductivity of said transistor; and means including a resistive divider connected between the terminals of said voltage source to apply a fixed bias to said second gate electrode, said last mentioned means including a capacitive impedance coupled between said second gate electrode and a terminal of said voltage source, whereby the control exercised on said conductive path by said second gate electrode is determined by the level of conductivity of said transistor.