Abstract: Low noise, low dropout regulators are described. An example low noise, low dropout regulator includes a chopping error amplifier to receive an input signal and a feedback signal and to output a modified signal having an undesired portion of the input signal shifted to a higher frequency and a regulator to receive the modified signal and to generate an output signal by filtering the undesired portion of the input signal from the modified signal.

Abstract: A startup circuit for use in a DC-DC converter having an input voltage terminal and an output voltage terminal, with the output voltage terminal connected to an output capacitor and with said converter including a pass transistor for transferring charge from the input terminal to the output terminal. The startup circuit includes a control circuit configured to cause the pass transistor to conduct an output current during start up when the output terminal voltage is approaching a final regulated voltage, with the output current being comprised of first and second current components, with the first current component being proportional to the output voltage and the second current component being proportional to the input voltage, with the two components being combined so as to resist changes in the power dissipation in the pass transistor during startup.

Abstract: A startup circuit for use in a DC-DC converter having an input voltage terminal and an output voltage terminal, with the output voltage terminal connected to an output capacitor and with said converter including a pass transistor for transferring charge from the input terminal to the output terminal. The startup circuit includes a control circuit configured to cause the pass transistor to conduct an output current during start up when the output terminal voltage is approaching a final regulated voltage, with the output current being comprised of first and second current components, with the first current component being proportional to the output voltage and the second current component being proportional to the input voltage, with the two components being combined so as to resist changes in the power dissipation in the pass transistor during startup.

Abstract: A low drop-out voltage regulator uses a voltage subtractor circuit 36 to form a power supply rejection boost circuit. The voltage subtractor 36 is inserted between the pass element 20 and the amplifier 26 of the low drop-out regulator. The voltage regulator circuit includes a pass element 20 coupled between an input node and an output node; a voltage feedback circuit 28 and 30 coupled to the output node Vo; an amplifier 26 having an input coupled to the voltage feedback circuit; and a voltage subtractor 36 having a control node coupled to an output of the amplifier 26, an output coupled to a control node of the pass element 20, and an input coupled to the input node. The boost circuit improves supply noise rejection performance significantly without adding much complexity to the regulator system. The boost circuit is simple and consumes negligible silicon area and power.

Abstract: A low drop-out voltage regulator uses a voltage subtractor circuit 36 to form a power supply rejection boost circuit. The voltage subtractor 36 is inserted between the pass element 20 and the amplifier 26 of the low drop-out regulator. The voltage regulator circuit includes a pass element 20 coupled between an input node and an output node; a voltage feedback circuit 28 and 30 coupled to the output node Vo; an amplifier 26 having an input coupled to the voltage feedback circuit; and a voltage subtractor 36 having a control node coupled to an output of the amplifier 26, an output coupled to a control node of the pass element 20, and an input coupled to the input node. The boost circuit improves supply noise rejection performance significantly without adding much complexity to the regulator system. The boost circuit is simple and consumes negligible silicon area and power.