Datasheet

10
100
1k
10k
100k
FREQUENCY (Hz)
-70
-60
-50
-40
-30
-20
-10
0
10
dBV
DIAPHRAGM
AIRGAP
BACKPLATE
ELECTRET
CONNECTOR
LMV1012
IC
LMV1012
SNAS194H –NOVEMBER 2002–REVISED MAY 2013 www.ti.com
APPLICATION SECTION
HIGH GAIN
The LMV1012 series provides outstanding gain versus the JFET and still maintains the same ease of
implementation, with improved gain, linearity and temperature stability. A high gain eliminates the need for extra
external components.
BUILT IN GAIN
The LMV1012 is offered in 0.3 mm height space saving small 4-pin DSBGA packages in order to fit inside the
different size ECM canisters of a microphone. The LMV1012 is placed on the PCB inside the microphone.
The bottom side of the PCB usually shows a bull's eye pattern where the outer ring, which is shorted to the metal
can, should be connected to the ground. The center dot on the PCB is connected to the V
DD
through a resistor.
This phantom biasing allows both supply voltage and output signal on one connection.
Figure 21. 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. This filter improves the correlation of the measured data to the signal to noise ratio perceived by the
human ear.
Figure 22. A-Weighted Filter
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Product Folder Links: LMV1012