T7507 Quad PCM Codec with Filters,
Termination Impedance, and Hybrid Balance
Data Sheet
August 1999
Gain Flatness—Out of Band—High
Frequencies
Chip Set Performance Specifications
When using the T7507, L8567 SLIC, L7583
The transmit and receive directions’ frequency-depen-
dent loss relative to gain at 3400 Hz is shown below.
This specification is met by using the T7507, L8567
SLIC, L7583 solid-state switch, and 50 Ω protection
resistors (200 Ω + 680 Ω || 0.1 µF termination).
solid-state switch, and 50 Ω protection resistors, the
following line card requirements are achieved; specified
termination impedance is shown in Figure 5.
680 Ω
200 Ω
30
ACCEPTABLE
REGION
25
0.1 µF
5-5324a(F)
20
Figure 5. Termination Impedance
12.5
10
Gain
Table 21. Gain
Gain @
1020 Hz
Min
Typ
Max
Unit
0
Transmit
Receive
Receive
–0.7
–4.2
–7.7
0
0.3
dB
dB
dB
–5
–3.5
–7.0
–3.2
–6.7
3400
4000
4600
5000
FREQUENCY (Hz)
5-5340(F)
Gain Flatness—In Band
Figure 6. Transmit and Receive Direction
Frequency-Dependent Loss Relative to
Gain at 3400 Hz
Table 22. Gain Flatness—In Band
The in-band frequency-dependent loss relative to
gain at frequency = 1020 Hz, for the transmit and
receive directions. This specification is met by using
the T7507, L8567 SLIC, L7583 solid-state switch, and
50 Ω protection resistors (200 Ω + 680 Ω || 0.1 µF
termination).
The loss for frequencies 3400 Hz < f < 4600 Hz is given
by:
π(4000 – f)
b = 12.5 1 – sin---------------------------- dB
1200
Frequency (Hz)
Min
Max
Unit
300—400
400—600
–0.3
–0.3
–0.3
–0.3
–0.3
1.00
0.75
0.35
0.55
1.50
dB
dB
dB
dB
dB
600—2400
2400—3000
3000—3400
Lucent Technologies Inc.
21
AGERE [ AGERE SYSTEMS ]
