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High Precision Integrated Bipolar RC Oscillator

IP.com Disclosure Number: IPCOM000049578D
Original Publication Date: 1982-Jun-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Azzis, D: AUTHOR

Abstract

The figure illustrates an integrated bipolar RC oscillator which provides the maximum period that can be obtained with given R and C values. Frequency tolerance is better than 0.1 percent.

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High Precision Integrated Bipolar RC Oscillator

The figure illustrates an integrated bipolar RC oscillator which provides the maximum period that can be obtained with given R and C values. Frequency tolerance is better than 0.1 percent.

The oscillator includes a basic oscillating circuit which is comprised of transistors 11 and 24 and external precision components Rx and Cx, a compensation circuit and an output circuit. The compensation circuit permits the oscillation frequency F to be only dependent on timing components Rx and Cx and to be precisely that given by the following relation: (see original) In the compensation circuit, diodes 10 and 23 are matched with transistors 11 and 24, respectively, and cause the basic oscillating circuit to be regenerative by controlling its switchover. They also balance the VBE drops. Transistors 8 and 26 conduct a delta i current which is equal to about i/100 and produce equal drops across resistors Rx. By adding a current equal to 2i/ beta to that of the transistor 11 or 24 which is on, transistor 3 or 33 exactly maintains a current equal to i through Cx and a current equal to 2i through resistor Rx connected to the transistor which is on. This additional current is switched into the transistor 11 or 24 by transistor 2 or 35 which is controlled by the OUT or OUT signal, respectively. Matched pairs of transistors 14,21 and 17,19 increase the amplitude of the signals across the resistors Rx so as to improve the accuracy of the...