LMV1088 Datasheet, PDF (1/22 Pages) National Semiconductor (TI) – Dual Input, Far Field Noise Suppression Microphone Amplifier with Automatic Calibration Ability

December 10, 2007
LMV1088
Dual Input, Far Field Noise Suppression Microphone
Amplifier with Automatic Calibration Ability
General Description
The LMV1088 is a fully analog dual input microphone array
amplifier designed to reduce background acoustic noise,
while delivering superb speech clarity in voice communica-
tions applications.
The LMV1088 incorporates calibration circuitry which may be
initiated by either an I²C command or by a logic level control
on a separate input pin. The calibration sequence compen-
sates for gain and frequency response variations of the mi-
crophones used with the LMV1088, eliminating the need to
use expensive matched microphone sets. The calibration da-
ta is stored in the internal EEPROM memory. The LMV1088
has two differential input microphone amplifier channels plus
far field noise suppression (FFNS) processing circuitry. The
amplifiers and FFNS circuitry are adjustable for gain differ-
ences in the MIC channels of +/- 3dB. The frequency re-
sponse variations of the microphones over the voice band
frequency range can also be adjusted for differences of
+/-3dB.
The compensation or calibration function is achieved via
memory stored coefficients. These are determined when the
FFNS calibration fuction is activated. The purpose of the cal-
ibration sequence is to choose the optimized coefficients for
the FFNS circuitry for the given microphones, spacing, and
acoustical environment.
Key Specifications
(3.3V supply, unless otherwise specified)
■ ^{Supply voltage}
■ ^{Supply current}
■ ^{Signal to noise ratio (A-weighted)}
■ ^{Total harmonic distortion (A-weighted)}
■ ^{Temperature range}
2.7V to 5.5V
1mA (typ)
60dB (typ)
0.1% (typ)
−40°C to 85°C
Features
■ ^{Low power consumption}
■ ^{Neglectable noise suppression processing delay}
■ ^{Automatic Calibration}
■ ^{Three microphone usage modes}
■ ^{Space-saving 36 Bump micro SMD package}
Applications
■ ^{Cellular phones}
■ ^{Mobile and handheld two-way radios}
■ ^{Bluetooth and other powered headsets}
Application of the LMV1088
20213040
© 2007 National Semiconductor Corporation 202130
www.national.com