Frequency compensation circuit for adaptive on‐time control buck regulator

Abstract

A novel frequency compensation circuit for adaptive on-time control buck regulator is presented in this study, which mainly applied to provide power supply for double data rate synchronous dynamic random access memory system. Typical ripple control regulator possesses the advantage of fast transient response and unconditional stability. However, it suffers significant steady-state switching frequency variation when the input voltage and output voltage are varied. The on-time is directly proportional to the output voltage and inversely proportional to the input voltage so that the regulator can dynamically adjust the turn-on time of power switches according to the changes of input voltage and output voltage in steady-state operation by adaptive on-time control. Finally, an approximately fixed switching frequency is achieved. However, the variation of the switching frequency with load current still exists. Through the implementation of the frequency compensation circuit, the switching frequency variation caused by the load current variation can be effectively reduced in order to obtaining a more fixed switching frequency. The adaptive on-time control regulator with frequency compensation has been successfully fabricated with 0.35 µm 30 V complementary double-diffused metal oxide semiconductor process and full chip test results are provided to verify the proposed method in this study.

Fixed‐frequency adaptive on‐time buck converter with ramp compensation

“…Hence in the steady-state, the constant switching frequency f SW which depends only on the passive devices of resistors and capacitors is independent of the input voltage V IN and the output voltage V OUT and can easily be implemented. In actual application, variation of the load current has an influence on the switching frequency which can be effectively weakened by using a frequency compensation circuit [23]. A peak current mode controller is unstable whenever the steady-state duty cycle is >0.5, hence a slope compensation circuit is required to eliminate the sub-harmonic oscillations induced by a small perturbation of inductor current.…”

Three Phase Matrix Converter A Replacement of Rectifier Inverter Frequency Changer

“…This method has some limitations as snubber design complicates the bidirectional switches, which require more area and method have a poor response. [5] and [8] discussed methods of "semi-soft commutation method", the method is the most reliable method to commutate the current for bi-directional switches and depends upon the direction of the current. They do not require any snubber or inductance to decrease the losses.…”

Area‐efficient error amplifier with current‐boosting module for fast‐transient buck converters

“…For conventional PWM control, large compensation capacitor connected at the output of the error amplifier (EA) seriously deteriorates the response time of dc-dc converters. Many researches aim to enhance the transient response of dc-dc converters with different approaches [6][7][8][9][10][11][12][13][14][15][16]. To improve the transient response, an EA for increasing the source/sink current in the transient state is proposed in [6,7].…”