08005276 is referenced by 64 patents and cites 256 patents.

A fingerprint sensing circuit for reducing noise and parasitic capacitive coupling is disclosed in one embodiment of the invention as including a plurality of transmitting elements to sequentially emit a probing signal. A digital ground is provided to ground digital components in the fingerprint sensing circuit. A quiet ground, separate from and quieter than the digital ground, is provided to ground transmitting elements that are not transmitting the probing signal. Similarly, control logic is provided to connect, to the quiet ground, transmitting elements that are not transmitting the probing signal, while disconnecting, from the quiet ground, transmitting elements that are emitting the probing signal. The quiet ground helps to reduce the adverse effects of parasitic capacitive coupling and noise on the inactive transmitting elements.

Title
Apparatus and method for reducing parasitic capacitive coupling and noise in fingerprint sensing circuits
Application Number
12/98370
Publication Number
8005276 (B2)
Application Date
April 4, 2008
Publication Date
August 23, 2011
Inventor
Erik Jonathon Thompson
Phoenix
AZ, US
Jaswinder Jandu
Chandler
AZ, US
Richard Alexander Erhart
Tempe
AZ, US
Gregory Lewis Dean
Phoenix
AZ, US
Agent
William C Cray
Cecily Anne O Regan
Greenberg Traurig
Assignee
Validity Sensors
CA, US
IPC
G06K 9/28
View Original Source