A new single inductor bipolar multiple output (SIBMO) boost converter using pulse frequency modulation (PFM) control for OLED drivers and optical transducers

This study proposes a single-inductor bipolar multiple-output (SIBMO) boost converter utilizing pulse frequency (PFM) control for organic light-emitting diode (OLED) drivers and optical transducers. The purpose of the converter designed herein is to provide multiple voltage sources with opposite polarities to meet the requirements of various applications such as OLEDs or optical transducers. The bipolar voltage sources are essential for offering alternating driving voltages to extend the lifetime of OLEDs. The converter boosts the input of 2.8 V to two positive and two negative outputs, i.e., +12 V, +6 V, -12 V, and -6 V. Different from the commonly-used pulse width modulation (PWM), the constant on-time (COT) approach is adopted herein with a dynamic charging algorithm to automatically adjust the operating frequency, thus profiting from less circuit complexity, improvement of cross regulation, and high transfer efficiency in unbalanced load cases. The total maximum output power is 320 mW, as the switching frequency varies from 650 kHz to 0 Hz, and the maximum efficiency reaches 83.1% by simulation. The converter was fabricated by TSMC 0.25μm 1P3M high voltage CMOS technology for verification.