A novel DC-DC converter and LDO cascaded circuit with improved dynamic response and loop stability

Abstract

Presented is a new type of DC-DC converter and low dropout voltage regulator (LDO) cascaded circuit, which has improved dynamic response and loop stability. In this novel cascaded circuit, the gate voltage of the pass element of the LDO is quantized and compared with a target value to form an error value to finally control the feedback coefficient of the DC-DC converter. Meanwhile, the adjusting speed of this feedback coefficient can be changed dynamically through the gain compensator, which is minimized to obtain the best loop stability when approaching the steady-state and increased to achieve a fast transient response during large dynamic change. The testing results of the prototype designed to verify the feasibility show that the novel cascaded circuit can increase the response speed by 22 times and optimize the voltage ripple by 1.9 times.