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The Design of a Low-Power High-Speed Phase Locked Loop. Tiankuan Liu 1 , Datao Gong 1 , Suen Hou 2 , Zhihua Liang 1 , Chonghan Liu 1 , Da-Shung Su 2 , Ping-Kun Teng 2 , Annie C. Xiang 1 , Jingbo Ye 1 1 Department of Physics, Southern Methodist University, Dallas TX 75275, U.S.A. - PowerPoint PPT Presentation
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The Design of a Low-Power High-Speed Phase Locked Loop
Tiankuan Liu1, Datao Gong1, Suen Hou2, Zhihua Liang1, Chonghan Liu1, Da-Shung Su2, Ping-Kun Teng2, Annie C. Xiang1, Jingbo Ye1
1 Department of Physics, Southern Methodist University, Dallas TX 75275, U.S.A.
2 Institute of Physics, Academia Sinica, Nangang 11529, Taipei, Taiwan
2
Outline
• Introduction• PLL Design
– Block diagram– Layout– VCO design and simulation– Divider design and simulation
• PLL performances– Acquisition time– Deterministic jitter– Random jitter
• Conclusion• Acknowledgments
3
Introduction
Present Upgrade
Data rate per front-end board (FEB) (Gbps) 1.6 100
Power consumption per Gbps (mW) 1188 90
ATLAS Liquid Argon Calorimeter Optical Link Upgrade
• Silicon-on-Sapphire (SoS) CMOS technology– High speed, low power, high quality inductors, no latch-up– The radiation tolerance of a commercial 0.25 µm SoS CMOS technology has
been evaluated in the previous study
• Design Goals:– Operation frequency: 4 ~ 5 GHz for data rate 8 ~ 10 Gbps – Random jitter < 1 ps (RMS)
– Power consumption < 100 mW
• Application background
4
PLL Design: Block Diagram
LVDS Receiver
is the input
interfaceCML driver is used to drive
50 Ω coaxial cables
Phase frequency detector
Test points
2nd order passive Low pass filter with programmable bandwidth
charge pump with programmable current
(20, 40, 60, 80 µA)
LC-tank based voltage controlled oscillator
(VCO)
Divider (divide by 16)
5
PLL Design: Shared Blocks • The LVDS receiver, the phase frequency detector (PFD), the charge pump, the pass
filter, the CMOS divider, and the CML driver are shared with the 5 Gbps 16:1 serializer. For details of these design blocks please see the poster “A 16:1 serializer for data transmission at 5 Gbps” presented by Dr. Datao Gong at TWEPP, Paris France, September, 2009.
• The bandwidth of the low pass filter and the current of charge pump are programmable to suit different applications. The loop bandwidth and the phase margin are calculated in the following table.
Configuration C0C1C2 001 010 100
BW (MHz)
phase margin (deg)
BW (MHz)
phase margin (deg)
BW (MHz)
phase margin (deg)
Charge pump gain (µA)
20 0.42 46.33 0.84 46.34 1.68 46.33
40 0.72 56.29 1.44 56.30 2.88 56.31
60 1.02 59.50 2.04 59.50 4.08 59.53
80 1.31 59.99 2.63 59.99 5.25 60.04
6
PLL Design: Layout
Area 1.4 mm x 1.7 mm
7
PLL Design: VCO
VCO Type LC-tank based VCO
Ring oscillator-based VCO
Power Consumption Low High
Frequency High Low
Phase noise/jitter performance Good Bad
Radiation sensitivity Small Large
Tuning range Narrow Wide
Chip area Large Small
Comparison of two common type VCOs
8
PLL Design: VCO Schematic
Start-up circuit Reference
current source
On-chip spiral inductors with a peak frequency of 5.1 GHz. The Q factor is simulated to be 21.2 at 5 GHz.
Decoupling capacitors are used to improve the noise performance
Cross-coupled transistors provides negative resistance,
compensating the energy loss in the
LC tank
A NMOS or PMOS transistor with its source and drain tied together serves a varactor with monotonic C-V curve and large tuning range (Cmax/Cmin > 2).
9
PLL Design: VCO Simulation• The tuning range is 3.79 – 5.01 GHz at the typical corner and room
temperature and varies less than 8% in all corners and temperature range.
10
PLL Design: Dividers
• The divider consists of a CML divider (divide by 2), a CML to CMOS converter, and a CMOS divider (divide by 8)
• The dividers can work up to 5.1 GHz at all corners from -40 °C to 85 °C
11
PLL Design: CML Divider
12
PLL Design: CML to CMOS Converter
13
PLL Performances: Acquisition Time
The PLL tracks the input frequency and phase after 9 µs
14
PLL Performances: Deterministic Jitter
The deterministic jitter after tracking (9 µs) is less than 2 ps (peak-peak)
15
PLL Performances: Random Jitter
The random jitter due to the VCO’s phase noise, the dominant noise source, is less than 1 ps (RMS) from 10 kHz to 100 MHz
The phase noise of the VCO in the worst case
16
Conclusion: Simulated Results of the PLL
Tuning range (GHz) 3.78 – 5.01
power consumption (core PLL mW) 104
Area (including pads and decoupling caps, mm2) 1.4 x 1.7
Random Jitter from VCO (RMS, ps) < 1
Deterministic jitter after locking (peak-peak, ps) 2
Acquisition time (μs) 9
17
Conclusion: Status and Plan
• Fabrication: submitted on August 3, 2009; Chip delivery: November 28, 2009
• Test: in lab test: December 15, 2009; Radiation test: February - March, 2010
• Plan: apply this LC-based PLL and design a multi-channel 16:1 serializer with each channel working around 10 Gbps in 2011
18
Acknowledgments
• Grant: US-ATLAS R&D program for the upgrade of the LHC and the US Department of Energy grant DE-FG02-04ER41299.
• Peter Clarke, Jay Clementson, Yi Kang, Francis M. Rotella, John Sung, and Gary Wu from Peregrine Semiconductor Corporation for technical assistance.
• Justin Ross at Southern Methodist University for setting up and maintaining the software environment.
• Jasoslav Ban, Mauro Citterio, Christine Hu, Sachin Junnarkar, Valentino Liberali, Paulo Rodrigues Simoes Moreira, Mitch Newcomer, Quan Sun, Fukun Tang, and Carla Vacchi for technical assistance and reviewing of this design.