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Apparatus for a temperature compensation of a catheter tip pressure transducer

  • US 5,866,821 A
  • Filed: 02/08/1993
  • Issued: 02/02/1999
  • Est. Priority Date: 10/25/1990
  • Status: Expired due to Term
First Claim
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1. A compensation circuit for a resistance bridge with a pair of arms, wherein each arm includes a pair of resistors, one of which increases with strain, and another of which decreases with strain, comprising:

  • a) a power input, a ground reference, a positive signal output and a negative signal output of the resistance bridge providing a response across the signal outputs as a function of pressure applied to the resistance bridge and an electrical signal applied to the power input, the response including both temperature dependent errors and fixed offset errors;

    b) a voltage controlled current source connected across the power input and the ground reference, the voltage controlled current source having a bridge excitation output current directly proportional to a fixed circuit reference voltage;

    c) a buffer amplifier having a buffer input connected to the power input, the buffer amplifier configured as a voltage follower generating a buffer output voltage proportional to the power input voltage;

    d) an instrumentation amplifier with a positive terminal and a negative terminal connected to the positive signal output and negative signal output respectively to generate an initial output proportional to the response of the signal outputs;

    e) a correction signal generating means having a correction part which consists of a single resistor for correction of temperature dependent errors and a single resistor for correction of fixed offset errors connected in series between the output of said buffer amplifier and said ground reference, said correction part generating an initial offset current at the connection of said single resistor for correction of temperature dependent errors and said single resistor for correction of fixed offset errors, said correction signal generating means having means for inversely amplifying the initial offset current, said correction signal generating means generating a correction signal on the basis of said inversely amplified initial offset current and said buffer output voltage, wherein the value of said resistor for correction of temperature dependent errors is adjusted so as to compensate for said temperature dependent errors, and the value of said resistor for correction of fixed offset errors is adjusted so as to compensate for said fixed offset errors; and

    f) a reference input of the instrumentation amplifier connected for receiving the correction signal to modify the initial output in response to the correction signal.

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