An integrated voltage-mode PWM controlled buck converter with active compensation

Integrated step down DC to DC converters (buck converter) are widely used for battery powered devices. This paper presents an integrated voltage-mode PWM controlled buck converter for low power applications. A novel active compensation stage is implemented inside the buck converter to increase the loop control stability and to reduce stability dependence on the equivalent series resistance (ESR) of the output capacitor. The simulated phase margin of the control loop is 50 degree with 50mΩ ESR. A test chip is designed and fabricated in a 0.25 μm BiCMOS process. The measured peak efficiency of this buck converter with 30 mA load current is more than 87 percent and the measured output voltage ripple is less than 6 mV in steady-state.