U3761MB-T ATMEL [ATMEL Corporation], U3761MB-T Datasheet - Page 25

• Manufacturer Part Number: U3761MB-T
• Description: Universal Telephone IC - All Functions Integrated
• Manufacturer: ATMEL [ATMEL Corporation]

Equations for
Electrical
Characteristic
Parameters of the
Speech Circuit
4744A–CORD–09/03
The equations refer to the basic test circuit. If not otherwise specified, the switches in
the basic test circuit are inactive.
Transmit Gain
V
Line-loss Compensation Transmit
D GS = GS (at I
TX-mode: V
Line-loss Compensation Receive
D GR = GR (at I
RX-mode: V
Receiving Gain
RX-mode: V
Sidetone Reduction
TX-mode: V
Input Impedance of Microphone Amplifier
TX-mode: VMIC = 3 mV/1 kHz, S5 = open
Gain Change when Muted
V
Total Harmonic Distortion (THD)
n
GS
GR
GSTA
Ri
GRM
THD
1
MIC
gen
, ... n
=
=
=
= 100 mV/1 kHz, S5 = open, S8 = open
= 3 mV/1 kHz, S5 = open
------------------------------------------------ -
æ
è
=
=
20 log
V
--------------------------------- - 1
20 log
=
V
n
20 log
L(S6 = closed)
20 log
L(S6 = open)
= harmonics of high and low frequency group
20 log
´
´
´
´
´
50 k
MIC
MIC
gen
gen
æ
è
æ
è
------------
V
V
---------------- -
æ
ç
ç
è
L
L
æ
è
V
= 3 mV/1 kHz, S5 = open
= 300 mV/1 kHz, S7b
= 300 mV/1 kHz, S7b
= 3 mV/1 kHz, S5 = open
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
MIC
RECO
æ
è
V
---------------- -
= 73 mA) - GS (at I
V
= 73 mA) - GR (at I
L
---------------- -
V
n
RECO
L
V
1
RECO
–
ö
ø
V
L
´
L
ö
ø
ö
ø
U
ö
ø
LG
ö
ø
(Mute = inactive) -
(in TX-mode) + GR
2
+
n
1
´
U
HG
L
L
2
= 20 mA)
= 20 mA)
+
n
2
´
20 log
U
U
LG
LG
´
2
2
+
+
n
æ
è
U
V
---------------- -
2
HG
RECO
´
V
U
L
2
HG
ö
ø
2
(Mute = active)
+
...n
n
U3761MB-T
´
U
LG
2
+
n
n
´
U
HG
2
ö
÷
÷
ø
25