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Circuit with adjustable amplitude and rolloff frequency characteristics

  • US 4,545,258 A
  • Filed: 07/05/1983
  • Issued: 10/08/1985
  • Est. Priority Date: 07/05/1983
  • Status: Expired due to Term
First Claim
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1. An electrical circuit for providing an output signal having a frequency representative of an input signal which has a fundamental frequency which varies responsive to a parameter and noise components at frequencies other than the fundamental frequency, the circuit comprising:

  • amplifier means having an adjustable amplitude response for providing the output signal as a function of the input signal;

    filter means coupled to the amplifier means for filtering the output signal and at least partially determining the amplitude response of the amplifier means, the filter means having an adjustable rolloff frequency characteristic with an adjustable rolloff;

    first adjustable impedance means for adjusting the amplitude response of the amplifier means and the rolloff frequency characteristic of the filter means as a function of a control signal so that the rolloff frequency is substantially equal to the fundamental frequency; and

    control means for providing the control signal to the first adjustable impedance means to decrease the amplitude response and increase the rolloff frequency when the fundamental frequency increases and to increase the amplitude response and decrease the rolloff frequency when the fundamental frequency decreases.

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