A 56-Gb/s 8-mW PAM4 CDR with High Jitter Tolerance

Speaker: Guanrong Hou
Affiliation: Ph.D. Candidate

Via Zoom:  https://ucla.zoom.us/j/98600034008

Abstract:

Wireline transceivers find wide usage in today’s data centers, allowing high-speed data communication between chips, boards, and racks. The use of PAM4 signaling in such links alleviates the channel loss but introduces other difficulties in transceiver design. Specifically, the linearity and resolution issues have generally called for ADC-based PAM4 receivers. However, such architectures entail three drawbacks. First, the ADC and the subsequent digital processing consume high power, a particularly serious challenge in multi-lane applications. Second, the ADC clock must exhibit a very small jitter, e.g., less than 40 fs for a 7-bit converter sampling at 56 GHz. Third, the latency in the ADC and the digital processor limits the overall clock recovery loop bandwidth and jitter tolerance.

An “analog” receiver, on the other hand, can greatly relax all three issues but it requires both a CDR circuit and a DFE that robustly process PAM4 signals. This work demonstrates the former by introducing several new ideas. The prototype provides a 3X improvement in power efficiency and 5X increase in jitter tolerance bandwidth. An analog one-eighth-rate CDR circuit detects both major and minor transitions in PAM4 data by calculating the Euclidean distances between the sampled points. Realized in 28-nm CMOS technology, the prototype exhibits a jitter transfer bandwidth of 160 MHz and a jitter tolerance of 1 UI at 10 MHz.

Biography: 

Guanrong Hou is working towards a PhD degree advised by Professor Behzad Razavi. He received B.S. in Electrical Engineering from Peking University in 2014 and M.S. in Electrical Engineering from UCLA in 2015. He received UCLA EE’s 2015 Prelim Top Performer award in CES track. He interned at Tensorcom, Inc. and designed a channel-select baseband amplifier that was patented. His research interests include SERDES as well as RF, power, etc.

For more information, contact Prof. Behzad Razavi (razavi@ee.ucla.edu)

Date/Time:
Date(s) - Mar 15, 2021
10:30 am - 12:30 pm

Location:
Via Zoom Only
No location, Los Angeles
Map Unavailable