SAW oscillator with digital compensation for the temperature related frequency changes
Abstract
The inherent temperature instability of surface acoustic wave (SAW) clock oscillators is improved by the use of a thermometer oscillator circuit that senses temperature changes in the SAW substrate. The thermometer oscillator is used in combination with a calibrated programmable read only memory and a logic circuit and provides frequency corrections to the clock oscillator. The basic device is an oscillator clock circuit using a SAW substrate having a delay path orientation with good temperature stability. A second oscillator, the thermometer oscillator circuit, and the electronic compensation scheme are added in order to produce minimum temperature coefficient of delay over all temperatures in the range of interest. The thermometer oscillator delay path utilizes a high temperature coefficient of delay orientation of the same SAW substrate and at an appropriate angle to the clock oscillator delay path orientation. Its frequency of oscillation; is used as a highly accurate thermometer in order to control a correction signal applied to a variable phase shifter in the clock oscillator loop.
- Publication:
-
Air Force Interim Report
- Pub Date:
- December 1984
- Bibcode:
- 1984aifo.reptQQ...S
- Keywords:
-
- Crystal Oscillators;
- Surface Acoustic Wave Devices;
- Thermal Stability;
- Digital Transducers;
- Frequencies;
- Logic Circuits;
- Patents;
- Precision;
- Read-Only Memory Devices;
- Temperature Gradients;
- Thermometers;
- Electronics and Electrical Engineering