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Integrated circuit for transducers

  • US 5,189,380 A
  • Filed: 04/13/1992
  • Issued: 02/23/1993
  • Est. Priority Date: 04/13/1992
  • Status: Expired due to Term
First Claim
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1. An integrated circuit for VR transducers comprising:

  • a low power consumption amplitude stabilized oscillator circuit havinga sine wave oscillator having a first transistor pair with emitter and collector electrodes connected in push-pull arrangement, with the emitter electrodes connected across a secondary winding of a transformer and with the collector electrodes connected across a primary winding of the transformer, and further having a capacitive element connected across the primary winding, the oscillator producing a sinusoidal output signal,a first synchronous full wave phase sensitive demodulator means connected to the oscillator for receiving sinusoidal signals representative of the amplitude of the output and producing a full wave DC rectified signal,a high frequency filter means connected to the first demodulator means for smoothing the rectified signal to provide a control voltage,an amplifier means connected to the filter means for comparing the control voltage to a reference voltage and producing a control signal output to the oscillator;

    a linearity circuit havinga reference signal source connected across a secondary winding of the first transformer and producing a reference voltage,a sensor means having a variable transducer pair connected across a secondary winding of the first transformer and producing an output signal,an amplifier means connected to the sensor means for comparing the output signal and a reference voltage and producing an amplified signal;

    a second synchronous full wave phase sensitive demodulator means for producing a full wave DC rectified signal proportional to the amplified signal;

    a reference voltage means; and

    a level shifter means havingan amplifier means connected to the second demodulator means for comparing the rectified signal to the DC reference voltage and producing a modifying control signal output to the oscillator circuit.

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