US 3,942,131 AGranted

Low frequency two phase oscillator including variable feedback integrator circuits

AssigneeWestinghouse Electric Corp.

InventorAllan I. Bennett

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Abstract

A low frequency oscillator including a pair of novel integrator circuits and a resistive inverter circuit electrically connected together in cascade and having ganged gain control following each integrator. The novel integrator circuit includes an operational amplifier having first and second input terminals, said first input terminal being adapted for connection to a voltage source and including a resistor between said source and terminal. A first negative feedback loop including a capacitor is electrically connected between the output of the amplifier and the first terminal. A second positive frequency independent feedback loop is electrically connected between the output of the amplifier and the second input terminal. The second feedback loop preferably includes a voltage divider having a temperature variable resistor and a pair of independent heaters for varying the resistance of said resistor.

Claims7

Dependent claims

A two-phase low-frequency oscillator comprising first and second integrator circuits, each of said circuits including an operational amplifier having first and second input terminals and an output and including a first frequency dependent negative feedback loop connected between said first terminal and said output terminal, and a frequency independent positive feedback loop between said second input terminal and said output terminal;

a first gain control means having an input connected to the output of said first operational amplifier, and an output defining a first oscillator output terminal;
a second resistor connected to the output of said first gain control means, said second integrator circuit having a first input terminal connected to said second resistor;
a second gain control means having an input connected to the output of said second amplifier;
a third resistor connected to the output of said second control means;
means for changing the phase of the output of said second control means 180.degree. connected to said third resistor, the ouput of said phase changing means defining a second oscillator output;
a first resistor connected to the output of said phase changing means and to the first terminal of said first operational amplifier;
and sensing means connected to each of said second feedback loops for stabilizing said oscillator against drift.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 05/532,287Filed 12 Dec 1974 · division
Priority: 24 Jan 1974
Granted: 2 Mar 1976
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H03B 5/20
Generation of oscillations using amplifier with regenerative feedback from output to input: with frequency-determining element comprising…
G06G 7/186
Using capacitive elements: using an operational amplifier comprising a capacitor or a resistor in the feedback loop
H03B 5/04
Details: modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
H03B 27/00
Generation of oscillations providing a plurality of outputs of the same frequency