Справочник Пользователя для Motorola Mobility LLC T56KT1

 shows the microphone circuit and 

 gives the microphone specifications.

The 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 microphone port specifications.

The headset microphone port is designed for use with, but not limited to, a headset audio device. 
It is located at pin 53 on the G30 81 pin LGA interface, named MIC_HDST.

It is designed as a single-ended input and should be referenced to the G30 analog ground.

The microphone input includes all the necessary circuitry to support a direct connection to a 
headset microphone device. It incorporates an internal bias voltage of 2.0V through a 3.0kΩ 
resistor, and has an impedance of 1kΩ.

Input Voltage

No load
AT+MMICG=0

2.0

V

PP

Gain

Programmable in 
3 dB steps

0

45

dB

AC Input 
Impedance

1

kΩ

Bias voltage

R

BIAS 

= 3.0 kΩ

I

BIAS 

= 1 mA

1.8

2.0

2.2

V

Bias Current

1

mA