Pulse-width Modulation Technique for Generation of Multiple Analog Voltages for On-chip Calibration

A technique based on pulse-width modulation for generating multiple analog voltages on-chip is presented. This technique is specially helpful for the calibration of voltage-to-time converters, which are becoming increasingly popular to implement analog-to-digital converters in the deep sub-micron processes. A clock signal of duty cycle 25% is demonstrated to act as proxy for an analog voltage of about 145 mV for the purpose of calibrating a voltage-to-time converter followed by a time-to-digital converter. Further, by simply changing the duty cycle of the clock to 50%, it can act as proxy for about 300 mV and 75% for about 380 mV.