POWER SUPPLY CIRCUIT HAVING VOLTAGE CONTROL LOOP AND CURRENT CONTROL LOOP

摘要

power supply circuit includes two pass transistors to conduct current to the output node from the voltage supply terminal. One of the pass transistors is small, while the other is larger. Is a small current through the transistor is controlled by the voltage control loop to adjust the voltage on the output terminal to a predetermined voltage. Is a large current through the transistor is controlled by the drain so that a high gain of the current control loop current through a small transistor current flowing through the large transistor. By reducing the current flow in the small transistor, the power supply noise rejection ratio of the power supply circuit (PSRR) is improved for the frequency up to 100 kHz. Die area occupied by the two pass transistors is reduced compared to the amount of the conventional power supply circuit in the die area of the pass transistor of similar performance.