T7507 Quad PCM Codec with Filters,
Termination Impedance, and Hybrid Balance
Data Sheet
August 1999
Transmission Characteristics (continued)
ac Transmission Characteristics (continued)
Table 19. Noise
Parameter
Transmit Noise
Symbol
NXP
Test Conditions
—
Min
—
Typ Max
Unit
—
—
—
–68
–75
–53
dBm0p
dBm0p
dBm0
Receive Noise
NRP
PCM code is A-law positive one
—
Noise, Single Frequency
f = 0 kHz—100 kHz
NRS
VFXIN = 0 Vrms, measurement at
VFRO, DR = DX
—
Power Supply Rejection Transmit
PSRX
PSRX
VDD = 5.0 Vdc + 100 mVrms:
f = 0 kHz—4 kHz
36
30
—
—
—
—
dB
dB
f = 4 kHz—50 kHz
Power Supply Rejection Receive
PCM code is positive one LSB.
VDD = 5.0 Vdc + 100 mVrms:
f = 0 kHz—4 kHz
36
40
30
—
—
—
—
—
—
dB
dB
dB
f = 4 kHz—25 kHz
f = 25 kHz—50 kHz
Spurious Out-of-band Signals at
VFRO Relative to Input
SOS
0 dBm0, 300 Hz—3400 Hz input
PCM code applied:
4600 Hz—7600 Hz
7600 Hz—8400 Hz
8400 Hz—50 kHz
—
—
—
—
—
—
–30
–40
–30
dB
dB
dB
Table 20. Interchannel Crosstalk (Between Channels)
Parameter
Symbol
Test Conditions
Min Typ Max
Unit
Transmit to Receive CTXX-RY
Crosstalk 0 dBm0
Transmit Levels
f = 300 Hz—3400 Hz
idle PCM code for channel under test;
0 dBm0 into any other single-channel VFXIN
—
—
—
–90
–90
–90
–75
–75
–75
dB
Receive to Transmit CTRX-XY
Crosstalk 0 dBm0
Receive Levels
f = 300 Hz—3400 Hz
VFXIN = 0 Vrms for channel under test;
0 dBm0 code level on any other single-channel DR
dB
dB
Transmit to Trans-
mit Crosstalk
0 dBm0 Transmit
Levels
CTXX-XY
f = 300 Hz—3400 Hz
0 dBm0 applied to any single-channel
VFXIN except channel under test,
which has VFXIN = 0 Vrms
Receive to Receive CTRX-RY
Crosstalk 0 dBm0
Receive Levels
f = 300 Hz—3400 Hz
0 dBm0 code level on any single-channel DR except
—
–90
–75
dB
channel under test, which has idle code applied
R
Note: For interchannel, crosstalk into the transmit channels (VFxIN) can be significantly affected by parasitic capacitive feeds from VF O out-
puts. PWB layouts should be arranged to keep these parasitics low. The equivalent resistor looking from VFxIN toward VITR (Figure 16)
should be kept as low as possible to minimize crosstalk. A maximum of 7 kΩ at 3 kHz is recommended. This is easily achievable in this
design with the structure as shown in Figure 16.
20
Lucent Technologies Inc.
AGERE [ AGERE SYSTEMS ]
