![background image](http://html1.mh-extra.com/html/telit-wireless-solutions/gl865-quad/gl865-quad_hardware-users-manual_1083599049.webp)
GL865 Hardware User Guide
1vv0300910 Rev.1 – 2011-07-22
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 49 of 79
10.
Audio Section Overview
The Base Band Chip of the GL865 provides one input for audio to be transmitted
(Uplink), that can be connected directly to a microphone or an audio source.
The bias for the microphone is already provided by the product; so the connection can
be done in both following ways:
For more information refer to Telit document : “ 80000NT10007a
Audio Settings Application Note “.
MIC connection
TIP: Since the J-FET transistor inside the microphone acts as
RF-detector-amplifier, ask vendor for a microphone with anti-EMI
1u
220n
220n
1K
1K
MIC/AF_IN+
MIC/AF_IN-
AGND
MODULE
-
+
INPUT
ADC
Vmic
Wire Or Ground Plane
1u
220n
220n
1K
2.2K
1
u
÷10u
MODULE
-
+
INPUT
ADC
Vmic
MIC/AF_IN+
MIC/AF_IN-
AGND
Integral Ground Plane