| 主权项 |
1. A capacitive fingerprint sensing device for sensing a fingerprint pattern of a finger, said capacitive fingerprint sensing device comprising:
a plurality of sensing elements, each including:
a protective dielectric top layer to be touched by said finger;an electrically conductive sensing structure arranged underneath said top layer;a charge amplifier connected to said sensing structure for providing a sensing voltage signal indicative of a change of a charge carried by said sensing structure resulting from a change in a potential difference between said finger and said sensing structure, said charge amplifier comprising:
a first input connected to said sensing structure;a second input;an output for providing said sensing voltage signal;a feedback capacitor connected between said first input and said output; andat least one amplifier stage between said first and second inputs, and said output; and a voltage-to-current converter for converting said sensing voltage signal to a sensing current signal indicative of said change of charge carried by said sensing structure, wherein said fingerprint sensing device further comprises readout circuitry connected to the voltage-to-current converter comprised in each of said sensing elements for receiving sensing current signals from said plurality of sensing elements and providing a representation of said fingerprint pattern based on said sensing current signals. |
