FPGAs have several voltage rails to consider. As semiconductor process technology advances, the required voltage levels decrease and the tolerance becomes tighter. For example, 5% total accuracy from a 3.3 V rail is 165 mV tolerance. Now for the Zynq 7000 FPGA, the same 5% tolerance from a 1 V rail is only 50 mV. For the higher performing FPGAs , such as the Virtex, Kintex and Artix 7 series of FPGAs, a 3% tolerance at 1 V is 30 mV. So, it is important to pay attention to the voltage regulation as well as the output voltage. Fortunately, some of the rails can be tied together to limit the number of voltage regulators, such as VCCINT and CCCBRAM. Analog voltages for on-board Phase-Locked-Loops are best suited with low noise LDOs. Analog circuits are sensitive to noise on the voltage and low noise LDOs with high power supply ripple rejection are good choices.