RXP and RXN. At TJ = –40°C to 125°C, unless otherwise noted.
PARAMETER |
MIN |
NOM |
MAX |
UNIT |
COMMENTS |
UI |
Unit interval |
399.88 |
400 |
400.12 |
ps |
Each UI is 400 ps 300 ppm. UI does not account for SSC dictated variations(1)
|
VRX-DIFFp-p
|
Differential input peak-to-peak voltage |
0.175 |
|
1.200 |
V |
VRX-DIFFp-p = 2*|VRXP - VRXN, |(2)
|
TRX-EYE
|
Minimum receiver eye width |
0.4 |
|
|
UI |
The maximum interconnect media and transmitter jitter that can be tolerated by the receiver is derived as TRX-MAX-JITTER = 1 - TRX-EYE = 0.6 UI(2)
(3)
|
TRX-EYE-MEDIAN-to-MAX-JITTER
|
Maximum time between jitter median and maximum deviation from median |
|
|
0.3 |
UI |
Jitter is defined as the measurement variation of the crossing points (VRX-DIFFp-p = 0 V) in relation to recovered TX UI. A recovered TX UI is calculated over 3500 consecutive UIs of sample data. Jitter is measured using all edges of the 250 consecutive UIs in the center of the 3500 UIs used for calculating the TX UI.(2) (3)
|
VRX-CM-ACp
|
AC peak common-mode input voltage |
|
|
150 |
mV |
VRX-CM-ACp = RMS(|VRXP + VRXN|/2 - VRX-CM-DC) VRX-CM-DC = DC(avg) of |VRXP + VRXN|/2(2)
|
RLRX-DIFF
|
Differential return loss |
10 |
|
|
dB |
Measured over 50 MHz to 1.25 GHz with the P and N lines biased at +300 mV and - 300 mV, respectively(4)
|
RLRX-CM
|
Common-mode return loss |
6 |
|
|
dB |
Measured over 50 MHz to 1.25 GHz with the P and N lines biased at +300 mV and 300 mV, respectively(4)
|
ZRX-DIFF-DC
|
DC differential input impedance |
80 |
100 |
120 |
Ω |
RX dc differential mode impedance(4)
|
ZRX-DC
|
DC input impedance |
40 |
50 |
60 |
Ω |
Required RXP as well as RXN dc impedance (50 Ω 20% tolerance)(2)
(5)
|
ZRX-HIGH-IMP-D
|
Powered down dc input impedance |
200 |
|
|
kΩ |
Required RXP as well as RXN dc impedance when the receiver terminations do not have power(6)
|
VRX-IDLE-DET-DIFFp-p
|
Electrical idle detect threshold |
65 |
|
175 |
mV |
VRX-IDLE-DET-DIFFp-p = 2*|VRXP - VRXN| measured at the receiver package terminals |
TRX-IDLE-DET-DIFF-ENTER-TIME
|
Unexpected electrical idle enter detect threshold integration time |
|
|
10 |
ms |
An unexpected electrical idle (VRX-DIFFp-p < VRX-IDLE-DET-DIFFp-p) must be recognized no longer than TRX-IDLE-DET-DIFF-ENTER-TIME to signal an unexpected idle condition. |
(1) No test load is necessarily associated with this value.
(2) Specified at the measurement point and measured over any 250 consecutive UIs. A test load must be used as the RX device when taking measurements. If the clocks to the RX and TX are not derived from the same reference clock, the TX UI recovered from 3500 consecutive UI is used as a reference for the eye diagram.
(3) A TRX-EYE = 0.40 UI provides for a total sum of 0.60 UI deterministic and random jitter budget for the transmitter and interconnect collected any 250 consecutive UIs. The TRX-EYE-MEDIAN-to-MAX-JITTER specification ensures a jitter distribution in which the median and the maximum deviation from the median is less than half of the total UI jitter budget collected over any 250 consecutive TX UIs. It must be noted that the median is not the same as the mean. The jitter median describes the point in time where the number of jitter points on either side is approximately equal as opposed to the averaged time value. If the clocks to the RX and TX are not derived from the same reference clock, the TX UI recovered from 3500 consecutive UIs must be used as the reference for the eye diagram.
(4) The receiver input impedance results in a differential return loss greater than or equal to 15 dB with the P line biased to 300 mV and the N line biased to 300 mV and a common-mode return loss greater than or equal to 6 dB (no bias required) over a frequency 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 50Ω to ground for both the P and N line (i.e., as measured by a vector network analyzer with 50Ω probes). The series capacitors CTX is optional for the return loss measurement.
(5) Impedance during all link training status state machine (LTSSM) states. When transitioning from a PCIe reset to the detect state (the initial state of the LTSSM) there is a 5-ms transition time before receiver termination values must be met on the unconfigured lane of a port.
(6) The RX dc common-mode impedance that exists when no power is present or PCIe reset is asserted. This helps ensure that the receiver detect circuit does not falsely assume a receiver is powered on when it is not. This term must be measured at 300 mV above the RX ground.