Enfora Enabler III-G
Modem Integration Guide
6.6.24. Headset Microphone Input (Pin 55)
The headset differential inputs
HSMIC and AUXI can be
amplified by the differential
handset microphone amplifier.
This amplifier has two different
gains 4.9 dB or 25.6 dB and a
bias generator HSMICBIAS
provides an external voltage of
2 V or 2.5 V to bias the
microphone.
Headset Mic
Input
Parameter/Conditions Min
Typ
Max
Units
Maximum Input Range
Inputs 3 dBm0 (Maximum
digital sample amplitude with
PGA gain set to 0 dB),
AUXAMP
gain = 18 dB, Single
HSMIC
78
mV
RMS
Nominal Ref. Level
-10
dBm0
Microphone Pre-
Amplifier Gain
18
dB
Input resistance at
HSMIC
HSMIC single input,
AUXAMP
gain = 18 dB
(INMODE = 0101)
40.5 k
Ω
6.6.25. Headset Microphone Bias Output (Pin 53)
Mic Bias Output
Parameter/Conditions
Min
Typ
Max
Units
Set to 2.0 V
1.9 2.1
Vdc
Bias Voltage on Mic(+)
Set to 2.5 V
2.4 2.6
Vdc
Mic Bias Current
Capability
2.0
mA
GSM0308PB001
52
Version DRAFT – 2/9/2007