LUCL9310AP-D AGERE [Agere Systems], LUCL9310AP-D Datasheet - Page 51

• Manufacturer Part Number: LUCL9310AP-D
• Description: Line Interface and Line Access Circuit Full-Feature SLIC,Ringing Relay,and Test Access Device
• Manufacturer: AGERE [Agere Systems]

July 2001
ac Applications
First-Generation Codec ac Interface Network: Complex Termination
Transmit Gain
Transmit gain will be specified as a gain from T/R to
PCM, T
assumed to be 0 dB, and in the case of T/R being refer-
enced to some complex impedance other than 600
resistive, the effects of the impedance transformation
must be taken into account.
Again, specified complex termination impedance at T/R
is of the form:
First, calculate the equivalent resistance of this network
at the midband frequency of 1000 Hz.
R
Agere Systems Inc.
EQ
=
------------------------------------------------------------------------- -
2
X
Figure 17. Interface Circuit Using First-Generation Codec (Blocking Capacitors Not Shown)
f
1
(dB). Since PCM is referenced to 600
2
+
C
2
2
324.5
–I
R
T/R
1
f
R
2
R
2 2
R
1
+
2 2
(continued)
R
C
1
2
+
R
TGP
R
R
C
R
2
2
RCVN
RCVP
TGS
= 6.34 k
2
+
----------------------------------------------- -
1
C
G
+
2
2
Full-Feature SLIC, Ringing Relay, and Test Access Device
f
R
V
f
TX
2 2
2
R
C
2 2
0.1 F
C
5-6396(F)
and
2
2
T
XI
V
Using R
into account the impedance transformation:
T
T
impedance at the PCM and R
tip and ring. 20 log
loss/gain due to the impedance transformation.
Note in the case of a 600
at T/R 20 log
Thus, there is no power loss/gain due to impedance
transformation and T
Finally, convert T
T
The ratio of R
with a quad Agere codec such as T7504:
R
----------
R
REF
R
X
X (specified[dB])
X
X
R
R
T6
X
15
(dB) = T
(dB) = 20 log g
N1
N2
< 200 k
= g
C
N
EQ
TX
V
ITR
, calculate the desired transmit gain, taking
•
V
X (specified[dB])
REF
324.5
-------------- -
is the specified transmit gain. 600
R
R
X
/R
15
T3
GP
---------- -
R
600
R
R
T6
RCV
EQ
X
T6
TX
(dB) to a ratio, g
is used to set the transmit gain:
•
= 20 log
X
---------- -
R
600
---- -
M
1
(dB) = T
EQ
R
+ 20 log
(continued)
HB
represents the power
–
+
R
OP AMP
CODEC
pure resistive termination
x
EQ
X (specified[dB])
600
--------- -
600
is the impedance at
---------- -
R
600
CODEC
OUTPUT
DRIVE
AMP
TX
EQ
= 0.
:
.
5-6400.M (F)
is the
51