* The value of the low-pass filter capacitor is application dependent, see the application section for additional information.

VDD

GND

Mic

Bias

REF

Mic1+

1.1 k:

1.1 k:

1.1 k:

1.1 k:

VDD

1 PF

C1

10 nF

CVREF

RIN3

RIN1

CIN1

Mic2+

470 nF

CIN3

CIN4

CIN2

Mic2-

470 nF

470 nF

Mic1-

470 nF

RIN2

RIN4

Bias

Mute 1

Mute 2

GA0

GA1

GA2

GA3

+

-

Mode

Mode 0

Shutdown

SD

Mode 1

Mic

CNTRL

Post-Amp Gain

(6-18 dB)

GB0

GB1

GB2

Pre-Amp Gain

(6 - 36 dB)

Optimized

Audio

Ouput

*

OUT-

LPF-

Optimized

Audio

Ouput

*

OUT+

LPF+

+/-0.5 dB

matched

omnidirectional

microphones

Analog

Noise

Canceling

Block

LMV1091

Loud Mu

sic

Tra

ffic

Noise

Crowd Noise

Anno

unce

men

ts

Ma

ch

ine

No

ise

Near-Field Voice

Far-field noise, > 50 cm

Up to 4 cm

Pure analog solution

provides superior

performance over DSP

solutions

Far field noise reduced

by up to 20 dB in properly

configured and using

+/-0.5 dB matched

microphones

LMV1091

SNAS481C – OCTOBER 2009 – REVISED MAY 2013

www.ti.com

System Diagram

Typical Application

Figure 1. Typical Dual Microphone Far Field noise Cancelling Application

2

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