A controllable resistor and its applications in pole-zero tracking frequency compensation methods for LDOs

【摘要】 This paper presents a controllable resistor,which is formed by a MOS-resistor working in the deep triangle region and an auxiliary circuit.The auxiliary circuit can generate the gate-source voltage which is proportional to the output current of an low dropout regulator for the MOS-resistor.Thus,the equivalent output resistance of the MOS-resistor is inversely proportional to the output current,which is a suitable feature for pole-zero tracking frequency compensation methods.By switching the type of the MOS-resistor and current direction through the auxiliary circuit,the controllable resistor can be suitable for different applications.Three pole-zero tracking frequency compensation methods based on a single Miller capacitor with nulling resistor,unit-gain compensation cell and pseudo-ESR (equivalent serial resistor of load capacitor) power stage have been realized by this controllable resistor.Their advantages and limitations are discussed and verified by simulation results.更多还原

【Abstract】 This paper presents a controllable resistor,which is formed by a MOS-resistor working in the deep triangle region and an auxiliary circuit.The auxiliary circuit can generate the gate-source voltage which is proportional to the output current of an low dropout regulator for the MOS-resistor.Thus,the equivalent output resistance of the MOS-resistor is inversely proportional to the output current,which is a suitable feature for pole-zero tracking frequency compensation methods.By switching the type of the MOS-resistor and current direction through the auxiliary circuit,the controllable resistor can be suitable for different applications.Three pole-zero tracking frequency compensation methods based on a single Miller capacitor with nulling resistor,unit-gain compensation cell and pseudo-ESR (equivalent serial resistor of load capacitor) power stage have been realized by this controllable resistor.Their advantages and limitations are discussed and verified by simulation results.更多还原