Described is an apparatus which comprises: a power delivery distribution network (PDN) to provide a power supply to at least one circuit; and an on-die synchronous power supply noise injector to inject noise to the power supply on the PDN. Described is another apparatus which comprises: a PDN to provide power supply to various circuits; an on-die power supply noise (PSN) sampler to sample the power supply with an injected noise, wherein the PSN sampler to sample the power supply with at least two different clock signals; and a phase noise accumulator to randomize the periods of the at least two different clock signals.