Return Loss ---------------------This is an ECR item – ECR attached---------------
Date: 5/12/03
Name: Cliff Lee, Zale Schoenborn, Andy Volk Email: cliff.lee@intel.com,
zale.t.schoenborn@intel.co
m,
andy.m.volk@intel.com
Company: Mailstop:
C1. Intel Corporation C2. JF2-54
Address: 2111 NE 25th Ave
City: State/Province:
C3. Hillsboro C4. OR
Country: Zip/Postal Code: 97229
C5. USA
Phone: 503-264-8394 FAX: 503-264-6053
Your Company SIG Voting Member Name:
C6. Ramin Neshati
Phone: Email: ramin.neshati@intel.com
Brief description of the functional changes proposed:
Relax transmitter differential return loss from 12dB to 10dB. Changes to table 4-5 (page 213):
Errata for the PCI Express Base Specification, Revision 1.0a
Symbol Comments
Parameter Min Nom Max Units
RL TX-DIFF Measured over 50 MHz to
Differential 10 1.25 GHz
Return Loss
dB
See Note 4.
Relax receiver differential return loss from 15dB to 10dB. Changes to table 4-6 (pgs 216 & 217):
Symbol Comments
Parameter Min Nom Max Units
RL RX-DIFF Measured over 50 MHz to
1.25 GHz with differential test
Differential input signals of 300mV (RMS
10 dB value) swing around ground
Return Loss
-
applied to D+ and D lines.
See Note 9.
RL RX-CM Measured over 50 MHz to
1.25 GHz with differential test
Common Mode 6 input signals of 300mV (RMS
dB value) swing around ground
Return Loss
-
applied to D+ and D lines.
See Note 9.
Clarify return loss measurement conditions. Changes to Note 4 under table 4-5 (page 214):
Note 4 -
The Transmitter input impedance shall result in a differential return loss greater than or equal to
10 dB with differential test input signals of 300mV (peak value) swing around ground applied to
D+ and D- lines and a common mode return loss greater than or equal to 6 dB over a frequency
range of 50 MHz to1.25 GHz. This input impedance requirement applies to all valid input levels.
The reference impedance for return loss measurements is 50 ohms to ground for both the D+
and D- line (i.e., as measured by a Vector Network Analyzer with 50 ohm probes - see Figure 4-
25). Note that the series capacitors CTX is optional for the return loss measurement.
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Errata for the PCI Express Base Specification, Revision 1.0a
Clarify return loss measurement conditions. Changes to Note 9 under table 4-6 (page 217):
Note 9 -
The Receiver input impedance shall result in a differential return loss greater than or equal to 10
dB with differential test input signals of 300mV (peak value) swing around ground applied to D+
and D- lines and a common mode return loss greater than or equal to 6 dB over a frequency
ft
range of 50 MHz to 1.25 GHz. This input impedance requirement applies to all valid input levels.
The reference impedance for return loss measurements for is 50 ohms to ground for both the
D+ and D- line (i.e., as measured by a Vector Network Analyzer with 50 ohm probes – see
ra
Figure 4-25). Note: that the series capacitors CTX is optional for the return loss measurement.
D
Specification(s) this proposed change is against:
PCI Express Base Specification, rev. 1.0a
w
Benefits as a result of the proposed changes:
Allow the buffer and package design to meet a more realistic spec target.
ie
ev
An assessment of the impact to the existing revision and systems that currently conform
to the PCI specification:
Transmitter and receiver design will have a relaxed budget. However, additional simulations are
necessary to ensure receiver package design will have a sufficient “eye” opening at the die.
R
An analysis of the hardware implications:
Return Loss design targets change for transmitter and receiver package and buffer design.
Better definition for the measurements of return loss target using a VNA.
An analysis of the software implications:
3
Errata for the PCI Express Base Specification, Revision 1.0a
None.
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