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Low Cost Self Starting Temperature Compensated Nonsaturating Oscillator

IP.com Disclosure Number: IPCOM000084093D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

McDowell, JR: AUTHOR [+2]

Abstract

Most low-cost oscillators are not temperature compensated or self-starting, and most require additional circuitry to prevent saturation, or to improve symmetry. The circuit described is self-starting, and, by making use of integrated circuit tracking, is very precise due to temperature compensated, nonsaturated operation. Because this circuit is designed to operate with no load on the resonant circuit, it provides a practically perfectly symmetrical output waveform. The extremely low cost of this circuit is due to its use of integrated circuit technology, designed to minimize the number of external connections needed to operate.

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Low Cost Self Starting Temperature Compensated Nonsaturating Oscillator

Most low-cost oscillators are not temperature compensated or self-starting, and most require additional circuitry to prevent saturation, or to improve symmetry. The circuit described is self-starting, and, by making use of integrated circuit tracking, is very precise due to temperature compensated, nonsaturated operation. Because this circuit is designed to operate with no load on the resonant circuit, it provides a practically perfectly symmetrical output waveform. The extremely low cost of this circuit is due to its use of integrated circuit technology, designed to minimize the number of external connections needed to operate.

The resonant circuit, consisting of the capacitor C, the inductor L, and the damping resistor R, determines the operating frequency of this circuit.

Diodes D1, D2, D3, D4 are used to prevent the saturation of transistors T1 and T2 by shifting the operating points of T1 and T2 beyond the voltage swing of node 1. Constant-current sources I1 and I3 are equal and are used to give the level shift diodes a well defined operating point 11 also insures that this circuit starts to oscillate.

During normal operation, when the voltage at node 1 is greater than Vcc, T2 turns off and T1 turns on sinking an output current I(out) equal to I2. When node 1 drops below Vcc, T1 turns off and T2 turns on providing a drive current, equal to I2, to the resonant tank.

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