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Small current detector circuit and locator device using the same

  • US 6,075,520 A
  • Filed: 11/13/1997
  • Issued: 06/13/2000
  • Est. Priority Date: 11/15/1996
  • Status: Expired due to Term
First Claim
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1. A small current detector circuit comprising:

  • a first and a second capacitor;

    a pulse drive circuit which drives one terminal of each capacitor by a pulse signal and charges and discharges said capacitors in synchronism with the rise and fall of the applied pulse so as to generate a first and a second detection signal at the other terminal of each capacitor;

    a connection circuit having a first and a second input terminal for receiving said first and second detection signals, respectively, and a first and a second output terminal, said connection circuit connecting said first and second input terminals to said first and second output terminals, respectively, in synchronism with the rise of said pulse signal whereas said first input terminal is connected to said second output terminal and said second input terminal to said first output terminal in synchronism with the fall of said pulse signal;

    a current generator circuit which receives said first and second detection signals from said first and second output terminals, respectively, to generate a current representing the difference between the levels of said signals; and

    an integrator circuit for integrating the output current from said current generator circuit, at least one of said first capacitor and said second capacitor being provided in detection portion of the detector circuit.

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