Shanghai SIMCom Wireless Solutions Limited 8PSA301 ユーザーズマニュアル
Smart Machine Smart Decision
19
Microphone
Electret
Microphone
route as differential pair
& shielded by GND
Close to microphone
MIC1P
Module
GND_MIC
ESD
ESD
10pF
33pF
33pF
33pF
10pF
10pF
Figure 20: Microphone reference circuit
Note:
1.
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
Test conditions
Min
Typ
Max
Units
Microphone amplifier gain = 0 dB (minimum gain)
Input referred noise
Single-ended, A-weighted, capless
-
19.3
25.1
µVrms
Signal-to-noise ratio
Single-ended, A-weighted, capless
92.0
94.0
-
dB
THD+N ratio
Analog input = -1 dBV
f = 1.02 kHz; single-ended input; 200 Hz to
20 kHz bandwidth; capless
20 kHz bandwidth; capless
-
-86.0
-70.0
dB
Microphone amplifier gain = 6 dB
Input referred noise
Single-ended, A-weighted, capless
-
5.9
7.1
µVrms
Signal-to-noise ratio
Single-ended, A-weighted, capless
91.0
92.5
-
dB
THD+N ratio
Analog input = -1 dBV
f = 1.02 kHz; single-ended input;
200 Hz to 20 kHz bandwidth; capless
-
-85.0
-70
dB
Microphone amplifier gain = 24 dB (maximum gain)
Input referred noise
Single-ended, A-weighted, capless
-
3.4
4.2
µVrms
Signal-to-noise ratio
Single-ended, A-weighted, capless
84.2
85.4
-
dB
THD+N ratio
Analog input = -1 dBV
f = 1.02 kHz; single-ended input;
200 Hz to 20 kHz bandwidth; capless
-
-82.4
-76.0
dB
General requirements