Digital temperature-compensated oscillator

Abstract

A digital temperature-compensated oscillator comprises a crystal oscillator, a first memory previously storing digital temperature compensation data obtained by previously measuring the relation between the ambient temperatures and the frequency deviations of the crystal oscillator, a second memory for storing frequency offset amounts of the oscillation frequency of the crystal oscillator, a temperature sensor for outputting analog detection data relating to the ambient temperature, an A/D converter for converting the analog detection data to digital detection data, a readout circuit for reading out temperature compensation data corresponding to the digital detection data and stored in the first memory according to the digital detection data and reading out the frequency offset amount stored in the second memory according to the digital detection data, an operation circuit for effecting the following calculation by use of the readout temperature compensation data and readout frequency offset amount to derive digital control voltage, V.sub.c =V.sub.co +(K.sub.00 +V.sub.co K.sub.10 +K.sub.01 T).times.(.DELTA.F+.DELTA.F.sup.2 .times.K.sub.10 /2) where K.sub.00, K.sub.01 and K.sub.10 are constants, V.sub.co is an initial value of the control voltage, T is an ambient temperature and .DELTA.F is a frequency offset amount, a D/A converter for converting the digital control voltage into an analog control voltage, and a voltage-capacitance converter for receiving the analog control voltage and generating a control signal to be supplied to the crystal oscillator according to the received analog control voltage, wherein the frequency of the crystal oscillator is controlled according to the control signal.

Dependencies are inferred from the claim text.