Technical information

Audio Interface
32 G30 - Module Hardware Description December 15, 2009
Figure 2-16 shows the microphone circuit and Table 2-10 gives the microphone specifications.
Figure 2-16: Headset Microphone Circuit
Important: The headset microphone circuit design depends on the type of microphone device.
A series capacitor is required in case a passive microphone is used, or the
application provides a separate bias voltage to an active microphone circuit.
The internal G30 biasing circuit may also be used with an active microphone, which
corresponds to the headset microphone port specifications.
Differential Speaker (Handset) Port
The analog differential speaker port is the G30 power-up default active output for voice calls and
DTMF tones. It is located at pins 48 and 49 on the G30 81 pin LGA interface, named SPKR_N
and SPKR_P respectively.
It is designed as a differential output with 8Ω impedance, but may also be used as a single-ended
output referenced to the G30 analog ground.
The differential speaker output is used for the handset audio path.
Table 2-10:
Headset Microphone Port Specifications
Parameter Conditions Min Typ Max Unit
Input Voltage No load
AT+MMICG=0
2.0 V
PP
Gain Programmable in
1 dB steps
045dB
AC Input
Impedance
1kΩ
Bias voltage R
BIAS
= 3.0 kΩ
I
BIAS
= 1 mA
1.8 2.0 2.2 V
Bias Current 1 mA