Rainbow Electronics GM862-QUAD-PY - Manual (Page 54)

GM862-QUAD / PY Hardware User Guide
1vv0300748 Rev. 5 - 20/09/07
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 54 of 68
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.
9.5 Hands-Free Earphone (Low Power) Design
The same design considerations made for the handset are valid for the hands-free earphone.
+12dB
GM862-QUAD / PY