A switching power converter for DC-DC converting has an inductance coupled between a power output and a high side switch in a controller device. The controller device has an error amplifier coupled to the power output and a reference voltage for activating the high side switch. The controller device has a bypass circuit including a bypass switch coupled between the supply input and the power output, a bypass driver having a first input coupled to the power output and a second input coupled to the reference voltage, and an output coupled to the bypass switch for activating the bypass switch. The controller further has a high bypass current sensor for generating a transient signal based on a current via the bypass switch, and a bandwidth control circuit for increasing the bandwidth of the error amplifier based on the transient signal.

Power converter and controller device

In this paper, a method is presented to improve the transient response of a buck converter. This method is based on using dual-loop voltage-mode controller along with a segmented power transistor stage. The first control loop is a conventional voltage-mode feedback using a second order delta-sigma as the control block. The second loop controls the size of the switches during the transient time. Simulation results in a 0.18μm CMOS technology confirm that by applying this technique, output-voltage overshoot at start-up almost disappears and settling time decreases by 50%. The output settling time during the load current steps is also improved by up to 50%.

A switching buck converter with dual loop controller and segmented output stage with improved start-up and transient response

A new ripple controlled synchronous Buck converter featuring with improved transient response and low output voltage ripple is presented in this paper. The proposed modified ripple-based control (MRBC) technique adopting a novel ripple generate mechanism realizes the fast response ability by regulating the inductor current and output voltage through separate loops rapidly. In addition, a high-precision current sensor is utilized to form the current loop to improve the regulation accuracy. Meanwhile, the output voltage ripple is minimized by eliminating the requirement of a large ESR (equivalent series resistance) thanks to the introduced current loop. The proposed controller is implemented in a 0.5 μm BCD process of CSMC. Simulation results show that, during a 500 mA load current step change, the controller is able to regulate the output voltage to return to its nominal value within 2.6 μs with less than 50 mV overshoot/undershoot. The output voltage ripple is only 15 mV.

Yangbo Yi

Papers

A fast transient response synchronous Buck converter with modified ripple-based control (MRBC) technique