Oscillators – Automatic frequency stabilization using a phase or frequency... – Plural a.f.s. for a single oscillator
Patent
1982-03-25
1984-06-12
Grimm, Siegfried H.
Oscillators
Automatic frequency stabilization using a phase or frequency...
Plural a.f.s. for a single oscillator
331 17, 331 25, 331176, H03L 102, H03L 708
Patent
active
044544839
ABSTRACT:
A method for temperature compensating the output of an oscillator circuit and apparatus for performing the method. This method employs fractional cycle synthesis to maintain the output frequency of a voltage-controlled oscillator at a desired value, the reference frequency of the circuit being derived from a crystal oscillator. To calibrate the circuit, the crystal oscillator is cycled in temperature. The frequency output of the crystal oscillator is accurately counted while a digital signal representing temperature is generated by an analog-to-digital converter from a temperature sensor. A signal representing the relationship between crystal frequency and temperature is stored in a memory and is available during actual operation of the oscillator for temperature compensation. During oscillator operation the output of the memory, as it relates to an instantaneous ambient temperature of the crystal, is appropriately treated and then injected into a phase locked loop containing the voltage-controlled oscillator, thereby affecting the input voltage to the oscillator to control the frequency output thereof. The stabilized frequency output of the VCO is offset from the crystal reference frequency and it is this offset that is shifted by very small amounts to provide the desired compensation of the oscillator output.
REFERENCES:
patent: 3938316 (1976-02-01), Morokawa et al.
patent: 4015208 (1977-03-01), Hammer et al.
patent: 4159622 (1979-07-01), Akahane
patent: 4297657 (1981-10-01), Frerking
Cubic Corporation
Grimm Siegfried H.
Mis David C.
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