Voltage controlled oscillator

Claim 2

An oscillator for generating an output signal at a frequency which is controllable by means of a modulation signal applied to the oscillator, said oscillator comprising: a differential amplifier having an inverting input terminal, a noninverting input terminal, and an output terminal, said amplifier being operative to provide at said output terminal an output signal which is a highly amplifIed function of an input signal applied between said input terminals; a resistive network for applying a preselected amount of positive feedback from said output terminal to said noninverting input terminal; and variable delay means, including a capacitor, for applying to said inverting input terminal a negative feedback signal which is a delayed function of the amplifier output signal, the delay being a function of the value of said capacitor, thereby to cause said amplifier to oscillate at a frequency which is a function of the delay, said delay means including also modulating means for providing an AC signal which is synchronized with the amplifier output signal and which has an amplitude substantially proportional to the amplitude of said modulation signal, said AC signal being applied to said capacitor to vary the effective delay whereby the frequency of oscillation of said amplifier may be varied as a function of the amplitude of said modulation signal.

Claim 3

An oscillator as set forth in claim 1 wherein said amplifier is an integrated circuit differential amplifier providing close input circuit tracking.

Claim 4

An oscillator as set forth in claim 1 wherein said resistive network is a voltage divider connected between said output terminal and local ground for applying a predetermined proportion of said output signal to said noninverting input terminal.

Claim 5

An oscillator as set forth in claim 1 wherein said capacitor is connected between said inverting input terminal and local ground and wherein said delay means includes a resistance connected between said output terminal and said inverting input terminal.

Claim 6

An oscillator as set forth in claim 1 wherein modulating means comprises a signal chopper which operates on said modulation signal and is synchronized by the amplifier output signal. 6 An oscillator as set forth in claim 5 wherein said chopper is balanced and provides a square wave AC output signal having substantially no DC component.

Claim 7

An oscillator as set forth in claim 6 wherein said delay means includes a resistance connected between said output terminal and said capacitor for providing said delayed feedback signal and wherein the chopper output signal is applied to said capacitor through a second resistance for varying the effective delay as a function of the amplitude of said modulation signal.

Claim 8

An oscillator as set forth in claim 7 including a blocking capacitor in series with said second resistance.

Claim 9

An oscillator for generating an output signal at a frequency which is controllable by means of a modulation signal applied to the oscillator, said oscillator comprising: a differential amplifier having an inverting input terminal, a noninverting input terminal, and an output terminal, said amplifier being operative to provide at said output terminal an output signal which is a highly amplified function of an input signal applied between said input terminals; a resistive voltage divider for applying a preselected amount of positive feedback from said output terminal to said noninverting input terminal; signal delay means, including a capacitor connected to said inverting input terminal and a resistance connected between said output terminal and said inverting input terminal, for applying to said inverting input terminal a negative feedback signal which is a delayed function of the amplifier output signal thereby to cause said amplifier to oscillate at a frequency which is a function of the delay; a chopper which operates on said modulation signal and which is synchronized by the amplifier output signal thereby to generate an AC signal having an amplitude which is substantially proportional to the amplitude of said modulation signal; and means for applying said AC signal to said capacitor to vary the effective delay as a function of the amplitude of said modulation signal, whereby the frequency of oscillation of said amplifier may be varied under the control of said modulation signal.

Claim 10

An oscillator for generating an output signal at a frequency which is controllable by means of a modulation signal applied to the oscillator, said oscillator comprising: a differential amplifier having an inverting input terminal, a noninverting input terminal, and an output terminal, said amplifier being operative to provide at said output terminal an output signal which is a highly amplified function of an input signal applied between said input terminals; a resistive voltage divider for applying a preselected amount of positive feedback from said output terminal to said noninverting input terminal; signal delay means, including a capacitor connected to said inverting input terminal and a resistance connected between said output terminal and said inverting input terminal, for applying to said inverting input terminal a negative feedback signal which is a delayed function of the amplifier output signal thereby to cause said amplifier to oscillate at a frequency which is a function of the delay; a chopper which operates on said modulation signal and which is synchronized by the amplifier output signal thereby to generate an AC signal having an amplitude which is substantially proportional to the amplitude of said modulation signal; and means for applying said AC signal to said capacitor to vary the effective delay as a function of the amplitude of said modulation signal, whereby the frequency of oscillation of said amplifier may be varied under the control of said modulation signal.

Claim 11

An oscilLator for generating an output signal at a frequency which is controllable by means of a modulation signal applied to the oscillator, said oscillator comprising: a differential amplifier having an inverting input terminal, a noninverting input terminal, and an output terminal, said amplifier being operative to provide at said output terminal an output signal which is a highly amplified function of an input signal applied between said input terminals; a resistive voltage divider for applying a preselected amount of positive feedback from said output terminal to said noninverting input terminal; a capacitor connected between said inverting input terminal and local ground; a first resistance connected between said output terminal and said inverting input terminal thereby to generate at said inverting input terminal a signal which is a delayed function of the amplifier output signal thereby to cause said amplifier to oscillate at a frequency which is a function of the delay; a balanced chopper which operates on said modulation signal and which is synchronized by the amplifier output signal thereby to generate a square wave signal having a peak to peak AC amplitude which is substantially proportional varied the amplitude of said modulation signal and having substantially no DC component; and a second resistance for applying said square-wave signal to said capacitor to vary the effective delay as a function of the amplitude of said modulation signal, whereby the frequency of oscillation of said amplifier may be varied under the control of said modulation signal.

Claim 12

An oscilLator for generating an output signal at a frequency which is controllable by means of a modulation signal applied to the oscillator, said oscillator comprising: a differential amplifier having an inverting input terminal, a noninverting input terminal, and an output terminal, said amplifier being operative to provide at said output terminal an output signal which is a highly amplified function of an input signal applied between said input terminals; a resistive voltage divider for applying a preselected amount of positive feedback from said output terminal to said noninverting input terminal; a capacitor connected between said inverting input terminal and local ground; a first resistance connected between said output terminal and said inverting input terminal thereby to generate at said inverting input terminal a signal which is a delayed function of the amplifier output signal thereby to cause said amplifier to oscillate at a frequency which is a function of the delay; a balanced chopper which operates on said modulation signal and which is synchronized by the amplifier output signal thereby to generate a square wave signal having a peak to peak AC amplitude which is substantially proportional varied the amplitude of said modulation signal and having substantially no DC component; and a second resistance for applying said square-wave signal to said capacitor to vary the effective delay as a function of the amplitude of said modulation signal, whereby the frequency of oscillation of said amplifier may be varied under the control of said modulation signal.