A sub-1V voltage-mode DC-DC buck converter using PWM control technique

A sub-1V CMOS DC-DC buck converter with 90% efficiency is presented in this paper. The proposed buck converter uses a digital error amplifier that can make the input voltage lower than other conventional buck converters. The buck converter uses voltage-mode control with pulse width modulation (PWM) techniques. The ramp generator of buck converter uses a Schmitt trigger circuit to replace the bias circuit and comparator. The scheme can reduce the power consumption and improving the power efficiency. The buck converter has been implemented with a 0.18-µm CMOS process. The buck converter is designed and the operating frequency is at 1MHz with the inductor of 4.7-uH and the output capacitor of 47-uF to reduce component size and switching loss. Experimental results prove that the converter can be directly powered with 1-V input voltage and output 0.5-V voltage at 500-mA output current.