Abstract: The design and implementation of a novel ADC architecture called ring-ADC for digital voltage regulator module controllers are presented.Based on the principle of voltage-controlled oscillators’ transform from voltage to frequency,the A/D conversion of ring-ADC achieves good linearity and precise calibration against process variations compared with the delay-line ADC.A differential pulse counting discriminator also helps decrease the power consumption of the ring-ADC.It is fabricated with a Chartered 0.35μm CMOS process,and the measurement results of the integral and differential nonlinearity performance are 0.92LSB and 1.2LSB respectively.The maximum gain error measured in ten sample chips is ±3.85%.With sampling rate of 500kHz and when the voltage regulator module (VRM) works in steady state,the ring-ADC’s average power consumption is 2.56mW.The ring-ADC is verified to meet the requirements for digital VRM controller application.

Key words: voltage regulator module, DC-DC, ring-ADC, delay-line ADC, differential pulse counting discriminator