Low drop-out voltage regulator with power supply rejection boost circuit
First Claim
1. A circuit comprising:
- a pass element coupled between an input node and an output node;
a voltage feedback circuit coupled to the output node;
an amplifier having an input coupled to the voltage feedback circuit;
a voltage subtractor having a control node coupled to an output of the amplifier, an output coupled to a control node of the pass element, and an input coupled to the input node.
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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.
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Citations
20 Claims
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1. A circuit comprising:
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a pass element coupled between an input node and an output node;
a voltage feedback circuit coupled to the output node;
an amplifier having an input coupled to the voltage feedback circuit;
a voltage subtractor having a control node coupled to an output of the amplifier, an output coupled to a control node of the pass element, and an input coupled to the input node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A low drop-out voltage regulator circuit comprising:
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a pass transistor coupled between an input node and an output node;
a resistor divider having an input coupled to the input node;
an amplifier having a first input coupled to an output of the resistor divider;
a voltage subtractor coupled between the input node and a control node of the pass transistor, and an input of the voltage subtractor coupled to an output of the amplifier. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification