XR-T7295 Datasheet, PDF (10/20 Pages) Exar Corporation – DS3/Sonet STS-1 Integrated Line Receiver

XR-T7295
OUTPUT JITTER
The total jitter appearing on the RCLK output during
normal operation consists of two components. First,
some jitter appears on RCLK because of jitter on the
incoming signal. (The next section discusses the jitter
transfer characteristic, which describes the relationship
between input and output jitter.) Second, noise sources
within the XR-T7295 device and noise sources that are
coupled into the device through the power supplies and
data pattern dependent jitter due to misequalization of the
input signal, all create jitter on RCLK. The magnitude of
this internally generated jitter is a function of the PLL
bandwidth, which in turn is a function of the input 1s
density. For higher 1s density, the amount of generated
jitter decreases. Generated jitter also depends on the
quality of the power supply bypassing networks used.
Figure 12 shows the suggested bypassing network, and
Table 6 lists the typical generated jitter performance.
11_{ÎÎÎÎÎÎÎÎÎÎÎÎ0262408 ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ}
1.0 2.0
5.0 10 20
50 100
Frequency (MHz)
Figure 7. Loss Characteristic of 728A
Coaxial Cable (450 ft.)
140862_{ÎÎÎÎÎÎÎÎÎÎÎÎ000000 ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ}
1.0 2.0
5.0 10 20
50 100
Frequency (MHz)
Figure 8. Phase Characteristic of 728A
Coaxial Cable (450 ft.)
JITTER TRANSFER CHARACTERISTIC
The jitter transfer characteristic indicates the fraction of
input jitter that reaches the RCLK output as a function of
input jitter frequency. Table 6 shows Important jitter
transfer characteristic parameters. Figure 9 also shows a
typical characteristic, with the operating conditions as
described in Table 6. Although existing standards do not
specify jitter transfer characteristic requirements, the
XR-T7295 information is provided here to assist in
evaluation of the device.
Parameter
Typ Max
Unit
Generated Jitter¹
All 1s pattern
1.0
ns peak-to-peak
Repetitive “100”
1.5
pattern
ns peak-to-peak
Jitter Transfer
Characteristic²
Peaking
f 3dB
0.05 0.1
dB
205
kHz
Notes
1 _{Repetitive input data pattern at nominal DSX-3 level with VDD}
= 5V T_A = 25°C.
2 _{Repetitive “100 ” input at nominal DSX-3 level with VDD = 5V,}
T_A = 25°C.
Table 6. Generated Jitter and Jitter Transfer
Characteristics
Rev. 1.05
10