Temperature compensated frequency generating circuit
First Claim
1. A temperature compensated constant frequency generator comprising:
- a voltage controlled oscillator (VCO) generator having a frequency controlled by a control voltage which varies with temperature to compensate for the temperature dependency of said frequency to obtain a temperature compensated frequency,means to derive said control voltage by connecting a first forward-biased pn junction voltage which has a negative temperature coefficient in series with a voltage difference of two forward-biased pn junctions, said voltage difference having a positive temperature coefficient.
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Abstract
The frequency of an integrated oscillator is held constant by using temperature compensation to compensate for the component variations due to temperature variations. A voltage controlled oscillator, which has temperature dependent components, is compensated with a temperature dependent control voltage. The frequency of many kinds of oscillators such as a relaxation oscillators and ring oscillators can be held constant when the operating current is held constant. The operating current is often derived from a current source, which is a voltage to current converter with a current equal to the ratio of a control voltage to a resistance. Since semiconductor resistance has a positive temperature coefficient is used to obtain a temperature invariant current source. The positive temperature coefficient is obtained with the difference junction voltage of two forward-biased pn junction voltages. The magnitude can be controlled by junction areas of the two junctions. The magnitude can also be amplified.
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Citations
21 Claims
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1. A temperature compensated constant frequency generator comprising:
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a voltage controlled oscillator (VCO) generator having a frequency controlled by a control voltage which varies with temperature to compensate for the temperature dependency of said frequency to obtain a temperature compensated frequency, means to derive said control voltage by connecting a first forward-biased pn junction voltage which has a negative temperature coefficient in series with a voltage difference of two forward-biased pn junctions, said voltage difference having a positive temperature coefficient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification