Resistorless on-die high voltage power supply noise measurement

The knowledge of power supply noise profile in microprocessors can facilitate in improving the performance significantly. In the deep sub-micron process employing on-die voltage regulators to convert incoming higher voltage from motherboard to lower core voltage supply, the measurement of input voltage profile becomes further challenging. Voltage to frequency conversion is often used to convert local supply voltage to it´s corresponding digital value. The state-of-art solutions rely on low impedance voltage divider to generate acceptable voltage which modulates the frequency of voltage controlled oscillator (VCO). In this paper we present a novel high voltage compliant ring oscillator which can replace existing low voltage VCO and can perform with similar accuracy as state-of-art solutions.