Hands-free earphone (low power) design, 5 hands-free earphone (low power) design – Telit Wireless Solutions GE863-QUAD User Manual
Page 48
GE863-QUAD
GE863-PY
1vv0300715 Rev. 1 - 19/09/06
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The resulting gain and high pass cut can be obtained with the formula:
2
3
R
R
Gain
=
4
*
3
*
2
1
.
C
R
freq
π
=
[Hz]
And an example of internal Ear amplifier could be :
Some amplifier require a low impedance load at high frequency in order to avoid auto oscillation, this
can be made with a capacitor (100nF) in series with a resistor (15Ω).
When designing your application, remember to provide an adequate bypass capacitor to the amplifier
and place it close to the power input pin of the IC, keeping the traces as short as possible.
8.5 Hands-Free Earphone (Low Power) Design
The same design considerations made for the handset are valid for the hands-free earphone.
+12dB
GE863-QUAD / PY