Time constant automatic adjustment circuit for a filter circuit
First Claim
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1. An automatic adjustment circuit for adjusting a filter circuit, the filter circuit having a time constant, the adjustment circuit adjusting the time constant and receiving a reference frequency signal, said adjustment circuit comprising:
- oscillation means for generating an oscillation signal, said oscillation means including a time constant variable filter and a feedback amplifier connected to said variable filter for positive feedback; and
means for detecting a difference in phase between said reference frequency signal and said oscillation signal and generating a control signal for automatically adjusting the time constant of the filter circuit.
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Abstract
An automatic adjustment circuit for adjusting the time constant of a filter circuit. The adjustment circuit includes a source of reference frequency signal, an oscillator for generating an oscillation signal, and a detector for detecting the difference in one of phase and frequency between the reference frequency signal and the oscillation signal and generating a control signal for automatically adjusting the time constant of the filter circuit.
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Citations
9 Claims
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1. An automatic adjustment circuit for adjusting a filter circuit, the filter circuit having a time constant, the adjustment circuit adjusting the time constant and receiving a reference frequency signal, said adjustment circuit comprising:
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oscillation means for generating an oscillation signal, said oscillation means including a time constant variable filter and a feedback amplifier connected to said variable filter for positive feedback; and means for detecting a difference in phase between said reference frequency signal and said oscillation signal and generating a control signal for automatically adjusting the time constant of the filter circuit. - View Dependent Claims (2, 3, 4)
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5. A method for adjusting a time constant of a filter circuit comprising the steps of:
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generating an oscillation signal using a combination of a variable filter and an amplifier connected to provide positive feedback to said filter; comparing the phase of said oscillation signal with the phase of a reference frequency signal; generating a control signal in response to a difference in phase between said oscillation signal and said reference frequency signal; and adjusting said time constant of said filter circuit with said control signal. - View Dependent Claims (6)
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7. An automatic adjustment circuit for adjusting a filter circuit, the filter circuit having a time constant, the adjustment circuit adjusting the time constant and receiving a reference frequency signal, said adjustment circuit comprising:
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oscillation means for generating an oscillation signal, said oscillation means including a time constant and variable filter, a feedback amplifier connected to said variable filter for positive feedback; and means for detecting a difference in frequency between said reference frequency signal and said oscillation signal and generating a control signal for automatically adjusting the time constant of said filter circuit.
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8. A method for adjusting a time constant of the filter circuit comprising the steps of:
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generating an oscillation signal using a combination of a variable filter and an amplifier connected to provide positive feedback to said filter; comparing the frequency of said oscillation signal with the frequency of a reference frequency signal; generating a control signal in response to a difference in frequency between said oscillation signal and said reference frequency signal; and adjusting said time constant of said filter circuit with said control signal. - View Dependent Claims (9)
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Specification