PBL 388 12
Figure 7. Transmitter channel input
amplifier used to suppress ripple in the
mic. supply. (CMRR).
R1 = R2 ≈ 3k
R3 = R4 ≈ 100k
R5 = R6
F
2
+
Ref.
R3
C1 = C2
R4
R7
F
1
+
-
C2
C1
R2
R6
R5
2
3
R1
16
Mic.
C4
C3
Figure 8. Transmitter and receiver
channel rectifier characteristics.
VRxDet
+600
+400
+200
VRx in
10
7.5
5.0
2.5
0.5
≈ 2V
Vref
V
ref
mV
p
1.5
1.0
VTx in
-200
-400
-600
VTxDet
Figure 9. Relationship in timing between
the voltage levels at TxIn, TxDet and NDet
Txin
TxDetout
N
Det
V
V
Figure 10. Transmitter and receiver
channel output dynamics.
Rxout
(mV)
Txout
(mV)
500
400
300
200
100
500
400
300
200
100
V+ (V)
V+ (V)
3.4
2.8
3.0
3.2
3.4
2.4
2.6
2.8
3.0
3.2
2.4
2.6
7
ERICSSON [ ERICSSON ]
