Data Sheet
February 1998
T7503 Dual PCM Codec with Filters
Transmission Characteristics
(continued)
ac Transmission Characteristics
(continued)
Table 12. Interchannel Crosstalk (Between Channels) R
F
=
≤400
kΩ*
Parameter
Symbol
Test Conditions
Transmit to Receive CT
XX-RY
f = 300 Hz—3400 Hz
Crosstalk 0 dBm0
idle PCM code for channel under test;
Transmit Levels
0 dBm0 into any other single-channel VF
X
IN
Receive to Transmit CT
RX-XY
f = 300 Hz—3400 Hz
Crosstalk 0 dBm0
VF
X
IN = 0 Vrms for channel under test;
Receive Levels
0 dBm0 code level on any other single-channel D
R
Transmit to Trans-
CT
XX-XY
f = 300 Hz—3400 Hz
mit Crosstalk
0 dBm0 applied to any single-channel
0 dBm0 Transmit
VF
X
IN except channel under test,
Levels
which has VF
X
IN = 0 Vrms
Receive to Receive CT
RX-RY
f = 300 Hz—3400 Hz
Crosstalk 0 dBm0
0 dBm0 code level on any single-channel D
R
except
Receive Levels
channel under test which has idle code applied
Min
—
Typ
—
Max
–75
Unit
dB
—
—
–75
dB
—
—
–75
dB
—
—
–75
dB
* For Table 12, crosstalk into the transmit channels (VF
X
IN) can be significantly affected by parasitic capacitive feeds from GS
X
and VF
R
O out-
puts. PWB layouts should be arranged to keep these parasitics low. The resistor value of RF (from GS
X
to VF
X
IN) should also be kept as low
as possible (while maintaining the load on GS
X
above 10 kΩ per Table 4) to minimize crosstalk.
Table 13. Intrachannel Crosstalk (Within Channels) R
F
=
≤400
kΩ*
Parameter
Symbol
Transmit to Receive CT
XX-RX
Crosstalk 0 dBm0
Transmit Levels
Receive to Transmit CT
RX-XX
Crosstalk 0 dBm0
Receive Levels
Test Conditions
f = 300 Hz—3400 Hz
idle PCM code for channel under test;
0 dBm0 into VF
X
IN
f = 300 Hz—3400 Hz
VF
X
IN = 0 Vrms for channel under test;
0 dBm0 code level on D
R
Min
—
Typ
—
Max
–65
Unit
dB
—
—
–65
dB
* For Table 13, crosstalk into the transmit channels (VF
X
IN) can be significantly affected by parasitic capacitive feeds from GS
X
and VF
R
O out-
puts. PWB layouts should be arranged to keep these parasitics low. The resistor value of RF (from GS
X
to VF
X
IN) should also be kept as low
as possible (while maintaining the load on GS
X
above 10 kΩ per Table 4) to minimize crosstalk.
Lucent Technologies Inc.
9
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