By David Mulcahy, Texas InstrumentsPlanet Analog (Mar 30, 2009)
Over the years, various technologies have been used to transmit signals over backplane busses. As speeds increase to cater to the ever-growing volume of telecom and datacom traffic, the limitation of the older, single-ended and emitter-coupled logic techniques becomes apparent.
Multipoint, low-voltage differential signaling (M-LVDS) is an interface standard similar to LVDS. It provides the benefits of high-speed, low-power, and low-EMI transmission solutions to today's bus applications. M-LVDS is suitable for data, control, synchronization and clock signals.
In today's backplanes, high-speed signals carrying the payload data are typically point-to-point (one driver and one receiver) interfaces. These connect various core chips such as ASICs, FPGAs, DSPs, and similar. Properly terminated point-to-point interfaces offer the best performance for high-speed signals. Signaling levels used can be PECL, CML, VML and LVDS with speeds going up to 4Gbps and higher, Figure 1.
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