Capacitive fingerprint sensor circuit and inductor

Capacitive fingerprint sensor circuit and inductor

  • CN 104,217,193 B
  • Filed: 03/20/2014
  • Issued: 12/19/2017
  • Est. Priority Date: 03/20/2014
  • Status: Active Grant
First Claim
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1. A kind of 1. capacitive fingerprint sensor circuit, it is characterised in that including cancellation module and feedback amplifier, the cancellation moduleFirst input end is connected with the first external driving source, and the second input of the cancellation module is by being pressed against second inputFinger be connected with the second external driving source, the output end of the cancellation module is connected with the input of the feedback amplifier,The first external driving source and the signal of the second external driving source output are anti-phase each other, and the first external driving source is sentThe signal for entering to the signal of the cancellation module and the described second external driving source to be coupled to the cancellation module produces counteracting, obtainsTo the fingerprint induced signal related to fingerprint depth, the output end of the feedback amplifier exports amplified fingerprint sensing letterNumber;

  • The cancellation module includes inductance capacitance (Cs) and counteracting electric capacity (Cc), the inductance capacitance (Cs) input supported to be describedSecond input of the module that disappears, the inductance capacitance (Cs) output end and the counteracting electric capacity (Cc) output end connection, it is describedOffset electric capacity (Cc) input be the cancellation module first input end, the inductance capacitance (Cs) and the counteracting electric capacity(Cc) tie point be the cancellation module output end;

    Second input of the cancellation module includes induction plate, fingerIsolated between the induction plate by dielectric layer, form the inductance capacitance (Cs), the first input of the cancellation moduleEnd forms the counteracting electric capacity (C comprising pole plate is offset between the induction plate and the counteracting pole platec)。

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