Compensated low dropout with high power supply rejection ratio and short circuit protection
First Claim
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1. A low dropout (LDO) voltage regulator, comprising:
- a differential amplifier configured to amplify a differential between a reference voltage and a regulated output voltage;
a PMOS (P-channel Metal Oxide Semiconductor) pass transistor coupled to the differential amplifier and driven by an output of the differential amplifier;
a compensation capacitor coupled to an output node of the differential amplifier; and
an auxiliary amplifier comprising a low current open loop differential amplifier having a low current comprising 25 nano amps, wherein an output node of the auxiliary amplifier is coupled to the compensation capacitor, and wherein an input node of the auxiliary amplifier is coupled to the PMOS pass transistor.
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Abstract
Disclosed is a low dropout (LDO) voltage regulator that includes a differential amplifier configured to amplify a differential between a reference voltage and a regulated output voltage, a pass transistor coupled to the differential amplifier and driven by an output of the differential amplifier, a compensation capacitor coupled to an output node of the differential amplifier, and an auxiliary amplifier, wherein an output node of the auxiliary amplifier is coupled to the compensation capacitor, and wherein an input node of the auxiliary amplifier is coupled to the pass transistor.
20 Citations
24 Claims
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1. A low dropout (LDO) voltage regulator, comprising:
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a differential amplifier configured to amplify a differential between a reference voltage and a regulated output voltage; a PMOS (P-channel Metal Oxide Semiconductor) pass transistor coupled to the differential amplifier and driven by an output of the differential amplifier; a compensation capacitor coupled to an output node of the differential amplifier; and an auxiliary amplifier comprising a low current open loop differential amplifier having a low current comprising 25 nano amps, wherein an output node of the auxiliary amplifier is coupled to the compensation capacitor, and wherein an input node of the auxiliary amplifier is coupled to the PMOS pass transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for compensating a low dropout (LDO) voltage regulator, comprising:
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amplifying, by a differential amplifier, a differential between a reference voltage and a regulated output voltage; receiving, at a PMOS pass transistor coupled to the differential amplifier, an output of the differential amplifier; receiving, at a compensation capacitor, an output signal from an auxiliary amplifier, the auxiliary amplifier comprising a low current open loop differential amplifier having a low current comprising 25 nano-amps wherein the low current comprises a current of 25 nano amps, wherein the compensation capacitor is coupled to an output node of the differential amplifier, wherein an output node of the auxiliary amplifier is coupled to the compensation capacitor, and wherein an input node of the auxiliary amplifier is coupled to the PMOS pass transistor. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An apparatus for compensating a low dropout (LDO) voltage regulator, comprising:
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a differential amplifier configured to amplify a differential between a reference voltage and a regulated output voltage; a PMOS pass transistor coupled to the differential amplifier and driven by an output of the differential amplifier; a compensation means coupled to an output node of the differential amplifier; and an auxiliary low current open loop differential amplification means amplifier having a low current comprising 25 nano amps, wherein an output node of the auxiliary amplification means is coupled to the compensation means, and wherein an input node of the auxiliary amplification means is coupled to the PMOS pass transistor. - View Dependent Claims (22, 23)
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24. A low dropout (LDO) voltage regulator, comprising:
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a differential amplifier configured to amplify a differential between a reference voltage and a regulated output voltage; a PMOS (P-channel Metal Oxide Semiconductor) pass transistor coupled to the differential amplifier and driven by an output of the differential amplifier; a compensation capacitor coupled to an output node of the differential amplifier; and an auxiliary amplifier comprising a low current open loop differential amplifier, wherein an output node of the auxiliary amplifier is coupled to the compensation capacitor, and wherein an input node of the auxiliary amplifier is coupled to the PMOS pass transistor, wherein the differential amplifier uses a low bias current provided by a bandgap current source.
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Specification