LMV1032_15 Datasheet, PDF (7/18 Pages) Texas Instruments – LMV1032-25 Amplifiers for 3-Wire Analog Electret Microphones

LMV1032
www.ti.com
APPLICATION SECTION
SNAS233G – DECEMBER 2003 – REVISED MAY 2013
LOW CURRENT
The LMV1032 has a low supply current which allows for a longer battery life. The low supply current of 60µA
makes this amplifier optimal for microphone applications which need to be always on.
BUILT-IN GAIN
The LMV1032 is offered in the space saving small DSBGA package which fits perfectly into the metal can of a
microphone. This allows the LMV1032 to be placed on the PCB inside the microphone.
The bottom side of the PCB has the pins that connect the supply voltage to the amplifier and make the output
available. The input of the amplifier is connected to the microphone via the PCB.
DIAPHRAGM
x
ELECTRET
CONNECTOR
xx^xx^{x x}
x
x
IC
AIRGAP
BACKPLATE
LMV1032
V_CC
x
x
V_OUT
GND
Figure 20. Built-in Gain
A-WEIGHTED FILTER
The human ear has a frequency range from 20 Hz to about 20 kHz. Within this range the sensitivity of the human
ear is not equal for each frequency. To approach the hearing response weighting filters are introduced. One of
those filters is the A-weighted filter.
The A-weighted filter is usually used in signal-to-noise ratio measurements, where sound is compared to device
noise. It improves the correlation of the measured data to the signal-to-noise ratio perceived by the human ear.
10
0
-10
-20
-30
-40
-50
-60
-70
10
100
1k
10k
FREQUENCY (Hz)
100k
Figure 21. A-Weighted Filter
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