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14 DESIGN007 MAGAZINE I FEBRUARY 2022 By 1986, surface mount technology (SMT) had gained popularity and was accounting for 10% of the market. e need to increase functionality and to reduce the product size and time-to-market forced product designers to adopt this new technology. In 1990, I took on the challenge, attended the many trending SMT conferences and training courses, and changed our product development to the pro- cess. Programmable devices enabled us to use the same hardware with different strains of so- ware allowing the creation of multiple prod- ucts from the one PCB design. FPGAs reduced the need for application-specific ICs. e list goes on, but there was always constant change. As system performance increases, the PCB designer's challenges become more complex. e impact of lower core voltages, high fre- quencies, and faster edge rates has forced us into the high-speed digital domain. Power consumption has become a primary factor for FPGA selection. Whether the concern is abso- lute power consumption, usable performance, battery life, thermal challenges, or reliability, power consumption is at the center of it all. To reduce power consumption, IC manufacturers have moved to lower core voltages and higher operating frequencies which, of course, mean faster edge rates. e enhancements in driver edge rates have a significant impact on signal quality, timing, crosstalk, and EMC. e faster edge rate for the same frequency and same length trace creates ringing in an unterminated transmission line. is also has a direct impact on radiated emissions. Figure 1 shows the massive increase in emissions from 10 ns to 1 ns. When dealing with sub-nanosec- ond rise times, the emissions can easily exceed the FCC/CISPR Class B limits for an untermi- nated transmission line. As signal rise times increase, consideration should be given to the propagation time and reflections of a routed trace. If the propagation time and reflection from source to load are longer than the edge transition time, an elec- trically long trace will exist. If the transmission line is short, reflections still occur but will be overwhelmed by the rising or falling edge and may not pose a problem. But even if the trace is short, termination may still be required if the load is capacitive or highly inductive, to pre- vent ringing. Note that series terminators are the most effective for high-speed design. Power distribution network (PDN) planning is another relatively new technology that has become an essential, interrelated component of signal integrity analysis. However, main- Figure 1: Radiated emissions from the 10 ns edge rate (left) and 1 ns (right).