High efficiency DC-DC power converters are currently in great demand for battery-operated portable electronic devices. Due to the presence of active power management, the supply voltage and the supply current of digital systems change rapidly for power-performance optimization. As a result, DC-DC converters for powering up high performance digital systems must have fast dynamic response to both load transient- and reference- tracking. Dynamic response of conventional voltage-mode and current-mode switching converters are limited in load transient. V² control has been proposed and is able to achieve fast load transient response. However, the performance of the V² control power converters highly rely on the value of equivalent series resistance (ESR) of the output capacitor, which is a wi...[ Read more ]

High efficiency DC-DC power converters are currently in great demand for battery-operated portable electronic devices. Due to the presence of active power management, the supply voltage and the supply current of digital systems change rapidly for power-performance optimization. As a result, DC-DC converters for powering up high performance digital systems must have fast dynamic response to both load transient- and reference- tracking. Dynamic response of conventional voltage-mode and current-mode switching converters are limited in load transient. V² control has been proposed and is able to achieve fast load transient response. However, the performance of the V² control power converters highly rely on the value of equivalent series resistance (ESR) of the output capacitor, which is a widely varying parameter and thus the performance is not very reliable. Moreover, its inherent architecture improves the load transient response but sacrifices the reference tracking speed at the same time.

In this thesis, a control method, called current-voltage feedforward control, based on DOR (derivative output ripple voltage) control and End-Point-Prediction scheme, is proposed. A buck converter using this proposed control method can achieve the same fast load transient response as the V² control counterparts without relying on the ESR of output capacitor. In addition, the reference tracking speed of the buck converter is greatly improved.

The proposed buck converter has been implemented in AMS 0.35-μm CMOS technology. Measurement results show that the proposed converter can achieve fast and stable load transient response at low ESR and low output capacitance condition. In addition, reference tracking speed is improved by 25 times compared with the V² control buck converter.