MSC8144E Quad Core Digital Signal Processor Data Sheet, Rev. 0
Electrical Characteristics
Freescale Semiconductor
44
2.7.5.4
Transmitter Specifications
LP-Serial transmitter electrical and timing specifications are stated in the text and tables of this section. The differential return
loss, S11, of the transmitter in each case shall be better than
–10 dB for (baud frequency)/10 < freq(f) < 625 MHz, and
–10 dB + 10log(f/625 MHz) dB for 625 MHz
≤ freq(f) ≤ baud frequency
The reference impedance for the differential return loss measurements is 100
Ω resistive. Differential return loss includes
contributions from internal circuitry, packaging, and any external components related to the driver. The output impedance
requirement applies to all valid output levels. It is recommended that the 20–80% rise/fall time of the transmitter, as measured
at the transmitter output, have a minimum value 60 ps in each case. It is also recommended that the timing skew at the output
of an LP-Serial transmitter between the two signals comprising a differential pair not exceed 25 ps at 1.25 GB, 20 ps at 2.50
GB, and 15 ps at 3.125 GB.
Table 30. Short Run Transmitter AC Timing Specifications—1.25 GBaud
Characteristic
Symbol
Range
Unit
Notes
Min
Max
Output Voltage,
VO
–0.40
2.30
V
Voltage relative to COMMON of either signal
comprising a differential pair
Differential Output Voltage
VDIFFPP
500
1000
mVPP
Deterministic Jitter
JD
0.17
UIPP
Total Jitter
JT
0.35
UIPP
Multiple output skew
SMO
1000
ps
Skew at the transmitter output between lanes of a
multilane link
Unit Interval
UI
800
ps
±100 ppm
Table 31. Short Run Transmitter AC Timing Specifications—2.5 GBaud
Characteristic
Symbol
Range
Unit
Notes
Min
Max
Output Voltage,
VO
–0.40
2.30
V
Voltage relative to COMMON of either signal
comprising a differential pair
Differential Output Voltage
VDIFFPP
500
1000
mVPP
Deterministic Jitter
JD
0.17
UIPP
Total Jitter
JT
0.35
UIPP
Multiple Output skew
SMO
1000
ps
Skew at the transmitter output between lanes of a
multilane link
Unit Interval
UI
400
ps
±100 ppm
Table 32. Short Run Transmitter AC Timing Specifications—3.125 GBaud
Characteristic
Symbol
Range
Unit
Notes
Min
Max
Output Voltage,
VO
-0.40
2.30
V
Voltage relative to COMMON of either signal
comprising a differential pair
Differential Output Voltage
VDIFFPP
500
1000
mVPP
Deterministic Jitter
JD
0.17
UIPP
Total Jitter
JT
0.35
UIPP
Multiple output skew
SMO
1000
ps
Skew at the transmitter output between lanes of a
multilane link
Unit Interval
UI
320
ps
±100 ppm