Temperature-compensated crystal oscillator
AssigneeNippon Electric Co., Ltd.
InventorShigeaki Ashida
Life of this patent
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Abstract
A control voltage for a crystal oscillation circuit is formed by adding two separately generated voltages. One of these voltages is proportionally variable with changes of temperature. The other voltage generally follows the temperature-frequency slope characteristic of the crystal unit. A use of such a control voltage eliminates the requirement for designing specific voltage generator circuits for each respective type of crystal oscillator, thereby enabling a substantial reduction in the cost of manufacture.
Claims9
A temperature-compensated crystal oscillator including a voltage-controlled crystal oscillation circuit means comprising a quartz crystal means and a variable-capacitance diode means operated responsive to a control voltage for varying the oscillation frequency thereof, and a control-voltage generator circuit means for producing the control voltage to maintain the oscillation frequency variations with temperature within definite predetermined limits, said control-voltage generator circuit means comprising first means for generating a first voltage V.sub.1 (T) which is variable in proportion to changes in temperature T, said first voltage being represented by Vs (To)+.DELTA.V.sub.1 (T), where Vs(To) represents a reference voltage at a reference temperature To and .DELTA.V.sub.1 (T)=V.sub.1 (T)-Vs(To);
- second means including at least one thermistor and a plurality of resistors for generating a second voltage V.sub.2 (T) which varies in a curvilinear form responsive to changes in temperature T, said second voltage being represented by Vs(To)+.DELTA.V.sub.2 (T), where .DELTA. V.sub.2 (T)=V.sub.2 (T)-Vs(To);
- and third means for synthesizing said first and second voltages to produce said control voltage which is represented by:
- V.sub.S (T.sub.O)+G.sub.1 .DELTA.V.sub.1 (T)+G.sub.2 .DELTA.V.sub.2 (T), where G.sub.1 and G.sub.2 represent respective variable gains.
A voltage controlled and temperature compensated crystal oscillator comprising means for generating a first voltage having a characteristic which varies in proportion to temperature caused variations in the output of said oscillator, means for generating a second voltage which has a slope corresponding to the temperature-frequency slope of a crystal type which is used in said oscillator, means coupled to said first voltage generating means for converting said first voltage into a third voltage having a variable gain, means coupled to said second voltage generating means for converting said second voltage into a fourth voltage having a variable gain, means for adding said third and fourth voltages to derive a control voltage, and means for applying said derived control voltage to control said oscillator in a manner which compensates for variations in said characteristic responsive to temperature changes.
A crystal controlled and temperature compensated oscillator wherein said crystal has a temperature vs. frequency characteristic which may be represented by the slope of a line, said oscillator comprising first voltage generating means for producing a voltage which compensates for oscillation frequency changes derived from said crystal, said compensating voltage varying according to said slope of a line, first regulating means coupled to said first voltage generating means for converting the output of said first voltage generating means to have the particular slope characteristic corresponding to the average slope characteristic for the particular type of crystal that is used, second voltage generating means for producing a voltage which is variable with temperature, second regulating means coupled to said second voltage generating means for correcting a voltage having a variable gain which compensates for oscillation frequency variations that occur in said oscillator independently of said average variations for said crystal type, synthesizer means for adding the output of said two regulating means, and means responsive to the output of said synthesizer means for driving said oscillator means to provide an oscillation output which has said temperature compensations.
Dependencies are inferred from the claim text.