US 11,871,193 B2
Microphone system
John P. Lesso, Edinburgh (GB); and Thomas I. Harvey, Northcote (AU)
Assigned to Cirrus Logic Inc., Austin, TX (US)
Filed by Cirrus Logic International Semiconductor Ltd., Edinburgh (GB)
Filed on Mar. 1, 2023, as Appl. No. 18/176,555.
Application 18/176,555 is a continuation of application No. 17/710,152, filed on Mar. 31, 2022, granted, now 11,627,414.
Application 17/710,152 is a continuation of application No. 17/091,359, filed on Nov. 6, 2020, granted, now 11,323,810, issued on May 3, 2022.
Claims priority of provisional application 62/949,029, filed on Dec. 17, 2019.
Prior Publication US 2023/0209258 A1, Jun. 29, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04R 1/10 (2006.01); H04R 3/04 (2006.01); H03G 5/16 (2006.01); H04R 1/08 (2006.01); H04R 3/02 (2006.01); H04R 1/02 (2006.01)
CPC H04R 3/04 (2013.01) [H03G 5/165 (2013.01); H04R 1/08 (2013.01); H04R 1/1016 (2013.01); H04R 1/1041 (2013.01); H04R 3/02 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A microphone system, comprising:
a first transducer, for generating a first acoustic signal;
a second transducer, for generating a second acoustic signal;
a high-pass filter, for receiving the first signal and generating a first filtered signal, wherein the first transducer and the second transducer have different acoustic properties;
a low-pass filter, for receiving the second signal and generating a second filtered signal;
an adder, for forming an output signal of the microphone system as a sum of the first filtered signal and the second filtered signal;
a first band-pass filter, configured to receive the first signal during a calibration mode;
a second band-pass filter, configured to receive the second signal during the calibration mode;
an adjustable gain block; and
a feedback loop;
wherein the first band-pass filter and the second band-pass filter each have pass bands that encompass a first frequency at which the high-pass filter and the low-pass filter both pass signals;
wherein the feedback loop acts during the calibration mode to determine a gain value required such that the first signal and the second signal have the same magnitude at the first frequency; and
wherein, in operation of the microphone system, said required gain value is applied to the first filtered signal and/or to the second filtered signal before it is passed to the adder.