Accession Number : ADP001572

Title :   Dual Mode Digitally Temperature Compensated Crystal Oscillator,


Personal Author(s) : Rubach,Robert

Report Date : 1982

Pagination or Media Count : 5

Abstract : This paper describes a method of utilizing a low frequency mode of vibration of an AT cut resonator to temperature compensate a second AT cut resonator to an accuracy of + or - 2 pp 10 to the 7th power over the temperature range 0 degrees C to 70 degrees C. In the DMDTCXO (Dual Mode Digitally Temperature Compensated Crystal) a two loop oscillating scheme was developed to allow a 3.0 MHz AT cut resonator to vibrate in two modes of oscillation, approximately half the time each, as shown in Figure 1. The 810 kHz low frequency mode used was digitized to an eight bit address, and an eight bit correction word used to compensate the 3.0 MHz mode of the resonator. The second oscillating loop contains a second AT cut 3.0 MHz resonator that oscillates continuously. For one-half of the time the second resonator is phase-locked to the first resonator. During the remaining half cycle, the output is held at its previous value to present a continuous output from the system. If the frequency does not change too much before the loop is closed again, then the system can remain at a steady state frequency locked condition.

Descriptors :   *Frequency, *Control, *Symposia, *Crystal oscillators, *Temperature, Compensation, Digital systems, Dual mode, Vibration, Accuracy, Crystals, Resonators

Distribution Statement : APPROVED FOR PUBLIC RELEASE