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14 Small ceramic surface-mount capacitors with low ESR and ESL take up less room but only work for higher switching frequencies. Capacitor vendors offer special packages that help lower impedance. For example, changing geometry to put terminals on the long side, or having multiple interleaved terminals, can cut down on parasitic inductance, making these designs suitable for use with point-of-load (POL) power supplies that have high transient performance. • High-frequency power supply. To use fewer capacitors, POL power supplies must have low output impedance, fast transient response, and higher switching frequency. A general trend in the industry is to push the power supply design to higher frequencies, which requires more-efficient high-speed power metal oxide semiconductor field-effect transistors (MOSFETs) and inductors. A standard way to achieve high current is to parallel many channels for a multiple-phase POL supply. It's common today to design a 1-volt, 200-amp POL power supply with switching frequency at 500 kilohertz per phase. Each phase current can be up to 50 amps. Engineers are pushing that kind of power supply to operate at more than twice the switching frequency—to the megahertz range, with improved power devices, especially integrated FETs with drivers. A power supply switching at a higher frequency and with faster transient performance enables us to reduce inductor size and the number and size of capacitors on the output side, which reduces the PDN footprint and lowers cost. • High current and power dissipation. The goal is to make PDN impedance as low as possible, but in any system, there is also a series impedance from the PCB to the actual silicon die inside the FPGA or ASIC package. PDN designers do not have much control over that impedance. While system engineers are working hard to reduce '' A general trend in the industry is to push the power supply design to higher frequencies, which requires more efficient high-speed MOSFETs and inductors."

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