US 7,489,791 B2
A/D converter with integrated biasing for a microphone
Eric Jurgen Van Der Zwan, Eindhoven (Netherlands); Henricus J. Kunnen, legal representative; and Eise Carel Dijkmans, Eindhoven (Netherlands)
Assigned to Koninklijke Philips Electronics N.V., Eindhoven (Netherlands)
Filed on Jul. 05, 2001, as Appl. No. 9/899,449.
Claims priority of application No. 00202381 (EP), filed on Jul. 05, 2000.
Prior Publication US 2002/0071578 A1, Jun. 13, 2002
Int. Cl. H04R 3/00 (2006.01); H03M 1/06 (2006.01)
U.S. Cl. 381—113  [381/95; 341/143; 341/155; 330/296] 17 Claims
OG exemplary drawing
 
1. A combination of a microphone requiring a bias signal and a sigma-delta converter operable to supply a bias signal to the microphone and having an input connected to an output of the microphone, to convert a signal generated by the microphone into a digital signal at an output of the sigma-delta converter, wherein the sigma-delta converter comprises:
a loop filter, a sampler, a first feed back circuit for AC signals, including a first digital-to-analog converter, and a second feedback circuit for DC signals, including a second digital-to-analog converter, the bias signal for the microphone being derived from the second feedback circuit, and the first feedback circuit and the second feedback circuit both being coupled to an input of the loop filter.