GE864-QUAD V2 Hardware User Guide
1vv0300841 Rev.5
–
2017-05-11
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights
Reserved.
Page 52 of 77
10.2.
Electrical Characteristics
TIP:
Being the microphone circuitry the more noise sensitive,
its design and layout must be done with particular care. Both
microphone paths are balanced and the OEM circuitry must be
balanced designed to reduce the common mode noise typically
generated on the ground plane. However the customer can use
the unbalanced circuitry for its particular application.
10.2.1.
Input Lines Characteristics
“MIC_MT” and “MIC_HF” differential
microphone paths
Line Coupling
AC*
Line Type
Balanced
Differential input
voltage
≤
1,03V
pp
@
Mic
G=0dB
Gain steps
7
Gain increment
6dB per step
Coupling capacitor
≥
100nF
Differential input
resistance
50K
Ω
Input capacitance
≤ 10pF
(*) WARNING :
AC means that the signals from the microphone
have to be connected to input lines of the module through
capacitors which value has to be
≥
100nF. Not
respecting this constraint, the input stages will be damaged.
WARNING:
when
particular OEM application needs a
Single Ended
Input
configuration, it is forbidden connecting the unused
input directly to Ground, but only through a 100nF
capacitor.
Don’t forget that the useful input signal will be
halved in
Single Ended
Input
configuration.
