Modern FPGAs operate at a core voltage around 1V and therefore even small voltage fluctuations can lead to timing violations and logic errors. The Power Delivery Network (PDN) between a power supply and the FPGA core must be carefully designed to achieve a low output impedance over a broad range of frequencies. The present disclosure describes two techniques for characterization of the PDN: 1) to extract the DC resistance in the power delivery path, and 2) to identify the high impedance frequency band(s) in the PDN. An embedded impedance extraction tool is synthesized within the FPGA load, in coordination with a mixed-signal current-mode dc-dc converter. A self-calibrated Carry-Chain based ADC (CC-ADC) is used for high-speed sampling of the core voltage. By modifying the PDN based on the extracted results, the voltage operating range and reliability of a crossbar application may be greatly extended.