Because of the input/output bypassing requirements of newer FPGAs, capacitor types formerly used in lower speed or lower density designs may not be effective. Bypass capacitors, depending on their material, construction, and value, have different series reactances over frequency. By examining the data sheets for the various families, (i.e., X7R, Z5U), it becomes apparent that some are better suited for the application under consideration. Capacitor impedance variation with frequency is shown in the graph. The impedance minimum is at the self-resonant frequency of the capacitor, above this frequency the parasitic lead inductance dominates the reactive behavior of the “capacitor”. In the graph, an industry-standard type X7R monolithic 10 nanofarad ceramic 1206 chip capacitor has an impedance of 0.2 Ohm at 50MHz. However, at 500MHz, the impedance of the same capacitor is approximately 3 Ohm. The capacitor is ineffective when the energy stored is unavailable to the load due to the increase in effective impedance. Temperature range and aging affects must also be considered. Some capacitors have a low-impedance at room temperature, but may perform poorly at temperature extremes. Z5U capacitors may have lower ESR at high frequencies for large value capacitors (100nF to 330nF). However, they are not recommended for use below 10°C. As plus 20 percent to minus 80 percent rated parts, they require almost double the design value to be safe. It is best to consult the capacitor manufacturer's data sheets in the selection of a bypass capacitor series