A Pulse Width Modulator Using a High-Speed Comparator With Flexible Oxide TFT Technology

This letter presents a pulse-width modulator (PWM) using a novel high-speed comparator, whose duty cycle changes with respect to the variation in the input reference voltage. This circuit has shown a variation of 44% in the duty cycle of a PWM wave for an input reference voltage variation of 2 V from measurements. This circuit is showing an input referred offset voltage of 40 mV, an input rms noise voltage of 4 mV and a power consumption of 56 mu W . Further, the circuit is able to discriminate a minimum differential input voltage of 40 mV. The reliable operation was demonstrated with a maximum input signal frequency of 10 kHz and a clock frequency of up to 1 MHz at a supply voltage of 4 V under normal ambient conditions. This circuit was fabricated on a flexible 30- mu m thick polyamide substrate using an a-IGZO TFT technology.