1. University of Oklahoma
RapidIO Technology Applied in Multifunction Phased Array Radar (MPAR) (Introduction and literature Review) 
Yu Sun
Department of Electrical and Computer Engineering
Radar Innovations Laboratory
University of Oklahoma
Final Presentation of ECE Special Study
Advisor: Dr. Yan Zhang

2. RapidIO: High-speed Interconnect technology
Other High-speed transaction technologies:
Giga-bye Ethernet, PCI Express ……
Question:
Why RapidIO is preferred in Multifunction Phase Array Radar?

3. Future MPAR architecture
Transmit-Receive Elements (TR) partitioned into “sub-arrays”
Overlapped Sub-Array Beamformer --- controlled by analog circuitry
Digital Transceiver A/D conversion
Digital Beamforming (DBF) --- all beams are computed concurrently
~1 Tera (1012) operations per second
Radar Signal processor Data analysis, processing

4. Multifunction Phased Array Radar (MPAR)’s needs on high-speed data transportation
Estimated transportation throughput of the parallel DBF scheme:
1 Tera (1012) operations per second. (level of 1 Giga-byte/s I/O bandwidth)
significant challenge by using general-purpose programmable processors (e.g., DSPs)
but tractable using field programmable gate arrays (FPGAs)
Diagrams of fully parallel DBF design in MPAR
Characters of MPAR data communication:
complex network switches, high-speed transactions (Interconnection)

5. Interconnect Trends & Comparison

6. Current high-speed interconnect technologies
Communication speed
Successor to
applications
Gigabit Ethernet
1 Gbps
100Mbps Ethernet
Initial: WAN,LAN
Later: workstations,
PCs and laptops
PCI Express
<10 Gbps
PCI 2.3/PCI-X
Initial: PCs and Servers
Later: 3D graphics,
10GE NICs,Storage ,
PCI bridges
RapidIO
1-10 Gbps
Initially a processor interconnect technology
Initial: embedded systems
Later: Computing, defense,
networking & CPU
I/O

7. Advantage of RapidIO Protocol Efficiency comparison
(RapidIO, Gigabit-Ethernet and PCI Express)
Effective Bandwidth comparison

8. Example RapidIO Architecture: interconnection between systems & devices

9. Our Current Plan: Applying High-Speed Serial I/O to Phased Array Radar
Multifunction Phase Array Radar signal processing diagram
a. Acquire digital data from ADC ( in Phase Array Radar)
b. Implement RapidIO on FPGA
Use RapidIO to transfer data within & between FPGA boards
Build RapidIO physical channel on PCB

10. FPGA computer-aided system design design tools: Xilinx ISE 8.2
Overall design steps
FPGA computer-aided system design design tools: Xilinx ISE 8.2
Modelsim
challenges: understand, simulate and synthesize high-speed serial
protocols 1. 2.
RapidIO FPGA hardware realization FPGA board: Xilinx Virtex II – Pro
with RocketIO transceivers
challenges: Place & Route, hardware debugging
RapidIO signal integrity design & Test Design tools: HFSS 10.1
Ansoft Designer 3.5
multi-layer PCB (OrCAD)
challenges: design layout of differential pairs on PCB,
minimize noise & crosstalks,
optimize signal quality 3.

11. FPGA board: Xilinx Virtex II Pro
Virtex-II Pro Generic Architecture Overview
Processor blocks: Xilinx Power PC
CLB block: RAMs, LUT, MUX, ADDERs, Block Select RAMS, DCMs ……
RocketIO blocks the basis of Xilinx's RapidIO technology & protocol
Gb/s maximum serial communication speed

12. Our FPGA development kits P160 Communications Module 2
Xilinx Virtex-II Pro XC2VP20 FF1152 Kit
P160 Prototype Module with I/O Header
P160 Communications Module 2
P160 Analog Module

13. Xilinx RocketIO Transceiver Block Diagram
Clock correction
Channel bonding

14. Xilinx RocketIO Transceiver Block Diagram
8B/10B encoder/decoder
Digital Clock Management (DCM)

15. RapidIO signal integrity challenge: --- Gigabit transactions cause jitters, phase shift, cross-talk on wires --- difficult to layout communication wires on PCB
Eye diagram & mask
a. Jitter: Short-term variation of signal transaction from their ideal position.
b. Noise spikes

16. Differential Pairs Basis
Transmit (TX) & Receive (RX)
differential pair
N & P nodes of differential pair
Differential pair carry complementary signals
Advantage: less susceptible to noise, jitters, and cross-talks
Better Signal Integrity
EMI generation is greatly reduced.
This becomes more important as edge rates increase and higher
frequencies appear in I/O system.

17. Differential pair’s effect on noise
Example: Multi-layer PCB Stack-up
If two pair routed very closely together:
noise will affect both wires identically
Receiving gate:
Only interested in difference between
two signals
---- less susceptible to noise
Outer Trace Width 5.25 mil
Inner Trace Width 4.00 mil
Differential Spacing 6.75 mil
50 ohm single-ended
100 ohm differential

18. Scope eye diagram of normal test stimulus by 10
inch using conventional twisted line
Better eye diagram of Vertex II test platform differential channel with 2 feet of co-ax (Data Rate
= Gbps)

19. Conventional Differential Pair wires: Coupled microstrip
Coplanar strip
Strip lines
Still have problems:
Crosstalk
Radiated emission
New differential pair technology:
Twisted Differential Pair :
Overcome Crosstalk, Radiated emission
Twisted differential line on multi-layer PCB

20. Twisted Differential Pair : Overcome Crosstalk, Radiated emission
Comparison of the measured crosstalk
voltage waveforms of the two differential
line structures: Coulpled microstrip & TDL
Measured radiated emission spectrum
from the differential lines on a PCB.
(a) Radiation from the conventional differential line
(b) radiation from the proposed Twisted Differential Line.

21. Differential Pair Models & Simulation results Tools:
Black box of the left specific Differential Pair
Differential output with different output capacitances
Differential Pair
Models
&
Simulation results
Tools:
Avnet Designer 3.5
HFSS 9.1

22. Conclusion High-speed serial links are preferable in Phased Array
Radar
Large data flow rate in MPAR
High-speed serial transceiver
Save FPGA pin counts
How to implement RapidIO
FPGA
Physical layer PCB
Challenges in RapidIO design
How to keep good signal integrity?
Minimize noise, crosstalks, jitters……
Serial link technologies for RapidIO
Clock Correction, 8B/10B converter, Channel Bonding……