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Crystal Oscillator

IP.com Disclosure Number: IPCOM000092635D
Original Publication Date: 1966-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Arnold, RW: AUTHOR [+2]

Abstract

Drawing A illustrates an oscillator which produces a substantially pure sinusoidal output accurately referenced about ground and very symmetrical. The oscillator includes operational amplifier 1 with precision input and negative feedback resistors 2 and 3. Positive AC feedback, provided through crystal 4, is limited, for example, to +/-. 2 volt, by oppositely poled diodes 5 and 6.

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Crystal Oscillator

Drawing A illustrates an oscillator which produces a substantially pure sinusoidal output accurately referenced about ground and very symmetrical. The oscillator includes operational amplifier 1 with precision input and negative feedback resistors 2 and 3. Positive AC feedback, provided through crystal 4, is limited, for example, to +/-. 2 volt, by oppositely poled diodes 5 and 6.

Tank circuits 7 and 8 tune amplifier 1 to the desired frequency and ensure purity in the sine wave output. The negative DC feedback assures symmetry and referencing about ground. The ratio of the values of 2 and 3 determine the output level.

One form of amplifier is in drawing B. It includes two cascaded differential amplifier stages 10 and 11, current source 12 for the first stage and common mode rejection feedback circuit 13 cooperating with source 12. The output stage includes amplifiers 19 and 20. The amplifier of B is adapted for monolithic fabrication on a single semiconductor chip. Interconnection terminals for external components are assigned reference numerals 14...18.

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