Reflection suppression methods

EECS 713 Liyao Wang

Outlines

TheorySimulation circuitTermination• Source termination• Load termination• Thevenin termination• RC termination• Diode termination

Theory

𝑍 𝑠≠𝑍0≠𝑍𝐿

Reflection 1: Source reflectionReflection coefficient:

Reflection 2:Load reflectionReflection coefficient:

Figure_1

Theory

Figure_2[1]

Figure_3[1]

Set the voltage source as a dc source in which Vdc=100V, =150Ω, and =(10^16)

Simulation circuit

Simulation circuit Simulation Result

Source termination

• Advantage1) Easy to assemble2) Reduce ringing3) Increase signal integrity4) Reduce EMI

• Disadvantage1) Load reflection still there2) Increase the rise time of input signal3) Wasting power

Source termination

Source termination• Simulation result

Load termination

• Advantage1) Easy to assemble2) Reduce ringing3) Easy to find the resistor value

• Disadvantage1) Increase power consumption

Load termination

Load terminationSimulation result

Thevenin termination

Standard:

=

The standard is not required for all the situation.

Thevenin termination

• Advantage1) Good overshoot suppression

• Disadvantage1) Large current drive (increase power consumption)2) Increase the difficulty of layout3) Hard to choose the resistor value and Vcc value

Thevenin termination

Thevenin termination Simulation result

RC termination

• Advantage1) Absorbing all the reflection wave2) Low power consumption

• Disadvantage1) Increase signal delay2) The time constant of RC circuit may cause reflection3) In high speed digital design, need to be careful of the

capacitor value

RC termination

RC terminationSimulation Result

Reference

[1] Paul, Clayton R., Introduction to Electromagnetic compatibility, Wiley Series in Microwave and Optical Engineering, 2006.[2]Wakerly, John F., Digita l Design Principles and Practices, Pearson Education, Inc., 2006.[3] R. Jagdale, A. Reddy, and K. Sundeep, “Optimization of reflection issues in high speed printed circuit boards,” in Proceedings of the 12th International Conference on Networking, VLSI and Signal Processing, pp. 108–112, World Scientific and Engineering Academy and Society, 2010

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