SimCom SIM8905A User Manual page 19

Microphone
MIC1P
GND_MIC
Module
Note:
1. Internal MIC_BIAS pull-up is used to reduce BOM cost and PCB routing.
2. Single-ended capless input is the only supported configuration, but differential routing is recommended.
Table 9: Analog microphone input performance
Parameter
Microphone amplifier gain = 0 dB (minimum gain)
Input referred noise
Signal-to-noise ratio
THD+N ratio
Analog input = -1 dBV
Microphone amplifier gain = 6 dB
Input referred noise
Signal-to-noise ratio
THD+N ratio
Analog input = -1 dBV
Microphone amplifier gain = 24 dB (maximum gain)
Input referred noise
Signal-to-noise ratio
THD+N ratio
Analog input = -1 dBV
General requirements
route as differential pair
& shielded by GND
Figure 20: Microphone reference circuit
Test conditions
Single-ended, A-weighted, capless
Single-ended, A-weighted, capless
f = 1.02 kHz; single-ended input; 200 Hz to
20 kHz bandwidth; capless
Single-ended, A-weighted, capless
Single-ended, A-weighted, capless
f = 1.02 kHz; single-ended input;
200 Hz to 20 kHz bandwidth; capless
Single-ended, A-weighted, capless
Single-ended, A-weighted, capless
f = 1.02 kHz; single-ended input;
200 Hz to 20 kHz bandwidth; capless
Smart Machine Smart Decision
Close to microphone
33pF
10pF
33pF
10pF
33pF
10pF
Min
-
92.0
-
-
91.0
-
-
84.2
-
19
ESD
Electret
Microphone
ESD
Typ Max
19.3 25.1 µVrms
94.0 -
-86.0 -70.0
5.9 7.1 µVrms
92.5 -
-85.0 -70
3.4 4.2 µVrms
85.4 -
-82.4 -76.0
Units
dB
dB
dB
dB
dB
dB