Digital temperature-compensated oscillator
First Claim
1. A digital temperature-compensated oscillator comprising:
- a crystal oscillator;
first memory means previously storing digital temperature compensation data obtained by previously measuring a relation between an ambient temperatures and frequency deviations of said crystal oscillator;
second memory means for storing frequency offset amounts of an oscillation frequency of said crystal oscillator;
a temperature sensor for detecting the ambient temperature and outputting analog detection data relating to the ambient temperature;
A/D converting means for converting the analog detection data to digital detection data;
readout means for reading out temperature compensation data corresponding to the digital detection data and stored in said first memory means according to the digital detection data and reading out the frequency offset amount stored in said second memory means according to the digital detection data;
operation means for effecting the following calculation by use of the readout temperature compensation data and readout frequency offset amount to derive digital control voltage,
space="preserve" listing-type="equation">Vc=V.sub.co +(K.sub.00 +V.sub.co K.sub.10 +K.sub.01 T)×
(Δ
F+Δ
F.sup.2 ×
K.sub.10 /2) where K00, K01 and K10 are constants, Vco is an initial value of the control voltage, T is an ambient temperature and Δ
F is a frequency offset amount;
D/A converting means for converting the digital control voltage into an analog control voltage; and
voltage-capacitance coverting means for receiving the analog control voltage and generating a control signal to be supplied to said crystal oscillator according to the received analog control voltage;
wherein the frequency of said crystal oscillator is controlled according to the control signal.
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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)×(ΔF+ΔF2 ×K10 /2)
where K00, K01 and K10 are constants, Vco is an initial value of the control voltage, T is an ambient temperature and ΔF 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.
118 Citations
5 Claims
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1. A digital temperature-compensated oscillator comprising:
-
a crystal oscillator; first memory means previously storing digital temperature compensation data obtained by previously measuring a relation between an ambient temperatures and frequency deviations of said crystal oscillator; second memory means for storing frequency offset amounts of an oscillation frequency of said crystal oscillator; a temperature sensor for detecting the ambient temperature and outputting analog detection data relating to the ambient temperature; A/D converting means for converting the analog detection data to digital detection data; readout means for reading out temperature compensation data corresponding to the digital detection data and stored in said first memory means according to the digital detection data and reading out the frequency offset amount stored in said second memory means according to the digital detection data; operation means for effecting the following calculation by use of the readout temperature compensation data and readout frequency offset amount to derive digital control voltage,
space="preserve" listing-type="equation">Vc=V.sub.co +(K.sub.00 +V.sub.co K.sub.10 +K.sub.01 T)×
(Δ
F+Δ
F.sup.2 ×
K.sub.10 /2)where K00, K01 and K10 are constants, Vco is an initial value of the control voltage, T is an ambient temperature and Δ
F is a frequency offset amount;D/A converting means for converting the digital control voltage into an analog control voltage; and voltage-capacitance coverting means for receiving the analog control voltage and generating a control signal to be supplied to said crystal oscillator according to the received analog control voltage;
wherein the frequency of said crystal oscillator is controlled according to the control signal. - View Dependent Claims (2, 3, 4, 5)
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Specification