Reduced-Voltage Signaling

A number of clock repeater chips use reduced-voltage-signaling. By reduced-voltage signaling I refer to the use of a peak-to-peak voltage swing intentionally made smaller than the V CC voltage supplied to the chips. Examples of reduced-voltage logic systems include BTL, GTL, ECL, SSTL, and LVDS logic.

One advantage of reduced-voltage clock signaling is a tremendous savings in overall system power. Another big advantage is lowered EMI due to the smaller swing.

The price you must pay for the use of reduced-voltage components is an increased susceptibility to noise. Noise may come in the form of crosstalk from the other regular-voltage logic chips on the same system. Extra spacing must be enforced between any low-voltage pcb traces and traces used by other logic families. Noise may also come in the form of environmental radiation from nearby RF sources, ESD, or EMP events.


  • Reduced-voltage clock signaling saves power and cuts EMI at the expense of noise susceptibility.


Transmission Line Parameters

Performance Regions

Frequency-Domain Modeling

Pcb (printed-circuit board) Traces

Differential Signaling

Generic Building-Cabling Standards

100-Ohm Balanced Twisted-Pair Cabling

150-Ohm STP-A Cabling

Coaxial Cabling

Fiber-Optic Cabling

Clock Distribution

Time-Domain Simulation Tools and Methods

Points to Remember

Appendix A. Building a Signal Integrity Department

Appendix B. Calculation of Loss Slope

Appendix C. Two-Port Analysis

Appendix D. Accuracy of Pi Model

Appendix E. erf( )


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High-Speed Signal Propagation[c] Advanced Black Magic
High-Speed Signal Propagation[c] Advanced Black Magic
ISBN: 013084408X
Year: 2005
Pages: 163 © 2008-2017.
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