A Constant On-Time Buck Converter with VCO-based DC Offset Calibration Technique

Le résumé fourni par la source

The constant on-time (COT) buck converters have the advantage of simple control mechanism, excellent load transient response, and high efficiency, making them well-suited to meet the power requirements of modern electronic devices. However, the COT control mode has inherent limitations in output voltage accuracy, and load variations further affect this precision, which restricts its application in scenarios with stringent voltage accuracy demands. This paper presents a novel DC offset calibration circuit to enhance output voltage precision. The circuit integrates the DC error between the feedback signal VFBand the reference signal VREFusing the straightforward voltage-controlled oscillator (VCO) and Digital Logic module. The integration result is then digitized and encoded by the Digital Logic module, and a digital-to-analog converter (DAC) generates the output offset calibration result VRbased on this encoded value, effectively eliminating the output DC offset. The converter is implemented using a 0.18μm BCD process, with an input voltage range of 4.2 V to 5.5 V and an output voltage of 3.52 V. The output DC offset is effectively reduced to 0.545 mV, ensuring improved voltage accuracy.

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