A Four-Phase Buck Converter with Background-Calibrated Capacitor-Current Sensor for Fast Load-Transient Application

  • 劉 忠瑋

Student thesis: Doctoral Thesis

Abstract

In this thesis a background capacitor-current sensor (CCS) calibration with fixed frequency operation is proposed In previous works the procedure of the calibration for output capacitance (CO) parasitic resistance on CO (RESR) and parasitic inductance on CO (LESL) will change the switching frequency to present the characteristics of the output impedance (ZCo) However the output voltage ripple will be enlarged caused by the lower frequency Thus this work proposes a method to calibrate CCS under fixed switching frequency which can let output voltage ripple to meet the target specification no matter when during background calibration or normal operation The scenario of CCS calibration in previous works is limited to operate only under light load condition To increase the flexibility of CCS calibration this work can execute background CCS calibration under light load and heavy load condition In addition some auxiliary circuits are implemented in this work to achieve smooth transition of different phase counts reducing the fluctuation of output voltage These proposed techniques are implemented in TSMC 0 18μm CMOS process with a chip area of 2 538 mm2 Measurement results shows that the VO undershoot/overshoot and settling time are 33mV / 48mV and 48ns / 55 ns of a load-current step of 2A/5ns The VO undershoot/overshoot caused by phase transition when entering background calibration under 1A load current are 30mV and 5mV
Date of Award2019
Original languageEnglish
SupervisorTai-Haur Kuo (Supervisor)

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