Circuit for generating an output voltage and method for setting an output voltage of a low dropout regulator
First Claim
1. A circuit for generating an output voltage that is substantially constant despite process, voltage, or temperature variation in the circuit, the circuit comprising:
- an error amplifier having a first input, a second input, and a single-ended output, wherein the first input is electrically connected to a reference voltage, and the second input is electrically connected to an output node of the circuit via a feedback resistor, the feedback resistor including a first terminal electrically connected to the output node and a second terminal electrically connected to the second input;
a pass transistor including a control electrode electrically connected to the single-ended output of the error amplifier, a first electrode electrically connected to a power supply voltage, and a second electrode electrically connected to the output node of the circuit;
a current source configured to generate a reference current that changes when a resistance of the feedback resistor changes;
a first branch of a current mirror electrically connected to the current source, the reference current flowing through the first branch; and
a second branch of the current mirror electrically connected to the second terminal of the feedback resistor, wherein an output current that flows through the second branch and between the first and second terminals of the feedback resistor is based on (i) the reference current flowing through the first branch, and (ii) a mirror ratio of the current mirror,wherein the output node provides an output voltage of the circuit, and the current source includes;
a complementary metal-oxide-semiconductor (CMOS) operational amplifier including a first input, a second input, and a single-ended output, wherein the first input of the CMOS operational amplifier is electrically connected to the reference voltage,a first PMOS transistor having a source terminal electrically connected to the power supply voltage, and a gate terminal electrically connected to the single-ended output of the CMOS operational amplifier,a first resistor having a first terminal electrically connected to a drain terminal of the first PMOS transistor, and a second terminal electrically connected to the second input of the CMOS operational amplifier,a second resistor having a first terminal electrically connected to the second terminal of the first resistor, and a second terminal electrically connected to a ground reference voltage, anda second PMOS transistor having a source terminal electrically connected to the power supply voltage, a gate terminal electrically connected to the gate terminal of the first PMOS transistor, and a drain terminal electrically connected to the first branch of the current mirror.
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Accused Products
Abstract
A circuit for generating an output voltage and method for setting an output voltage of a low dropout regulator are provided. A current source is configured to generate a reference current, and an error amplifier has a first input, a second input, and a single-ended output. The first input is connected to a reference voltage, and the second input is connected to an output node of the circuit via a feedback resistor. A pass transistor includes a control electrode connected to the single-ended output of the error amplifier, a first electrode connected to a power supply voltage, and a second electrode connected to the output node of the circuit. A first branch of a current mirror is connected to the current source, and a second branch of the current mirror is connected to the second terminal of the feedback resistor. The output node provides an output voltage of the circuit.
20 Citations
20 Claims
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1. A circuit for generating an output voltage that is substantially constant despite process, voltage, or temperature variation in the circuit, the circuit comprising:
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an error amplifier having a first input, a second input, and a single-ended output, wherein the first input is electrically connected to a reference voltage, and the second input is electrically connected to an output node of the circuit via a feedback resistor, the feedback resistor including a first terminal electrically connected to the output node and a second terminal electrically connected to the second input; a pass transistor including a control electrode electrically connected to the single-ended output of the error amplifier, a first electrode electrically connected to a power supply voltage, and a second electrode electrically connected to the output node of the circuit; a current source configured to generate a reference current that changes when a resistance of the feedback resistor changes; a first branch of a current mirror electrically connected to the current source, the reference current flowing through the first branch; and a second branch of the current mirror electrically connected to the second terminal of the feedback resistor, wherein an output current that flows through the second branch and between the first and second terminals of the feedback resistor is based on (i) the reference current flowing through the first branch, and (ii) a mirror ratio of the current mirror, wherein the output node provides an output voltage of the circuit, and the current source includes; a complementary metal-oxide-semiconductor (CMOS) operational amplifier including a first input, a second input, and a single-ended output, wherein the first input of the CMOS operational amplifier is electrically connected to the reference voltage, a first PMOS transistor having a source terminal electrically connected to the power supply voltage, and a gate terminal electrically connected to the single-ended output of the CMOS operational amplifier, a first resistor having a first terminal electrically connected to a drain terminal of the first PMOS transistor, and a second terminal electrically connected to the second input of the CMOS operational amplifier, a second resistor having a first terminal electrically connected to the second terminal of the first resistor, and a second terminal electrically connected to a ground reference voltage, and a second PMOS transistor having a source terminal electrically connected to the power supply voltage, a gate terminal electrically connected to the gate terminal of the first PMOS transistor, and a drain terminal electrically connected to the first branch of the current mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18)
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16. A circuit for generating an output voltage that is substantially constant despite process, voltage, or temperature variation in the circuit, the circuit comprising:
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an error amplifier having a first input, a second input, and a single-ended output, wherein the first input is electrically connected to a reference voltage, and the second input is electrically connected to an output node of the circuit via a feedback resistor, the feedback resistor including a first terminal electrically connected to the output node and a second terminal electrically connected to the second input; a pass transistor including a control electrode electrically connected to the single-ended output of the error amplifier, a first electrode electrically connected to the power supply voltage, and a second electrode electrically connected to the output node of the circuit; a current source configured to generate a reference current that changes when a resistance of the feedback resistor changes; a current mirror including; a first NMOS transistor including a source terminal electrically connected to a ground reference voltage, a gate terminal electrically connected to a drain terminal of the first NMOS transistor, and the drain terminal electrically connected to the current-mode bandgap reference circuit, wherein the reference current flows between the drain and source terminals of the first NMOS transistor, and a second NMOS transistor including a source terminal electrically connected to the ground reference voltage, a gate terminal electrically connected to the gate terminal of the first NMOS transistor, and a drain terminal electrically connected to the second terminal of the feedback resistor, wherein an output current that flows between the drain and source terminals of the second NMOS transistor is based on the reference current and a mirror ratio of the current mirror, wherein the output node provides an output voltage of the circuit, and the current source includes; a complementary metal-oxide-semiconductor (CMOS) operational amplifier including a first input, a second input, and a single-ended output, wherein the first input of the CMOS operational amplifier is electrically connected to the reference voltage, a first PMOS transistor having a source terminal electrically connected to the power supply voltage, and a gate terminal electrically connected to the single-ended output of the CMOS operational amplifier, a first resistor having a first terminal electrically connected to a drain terminal of the first PMOS transistor, and a second terminal electrically connected to the second input of the CMOS operational amplifier, a second resistor having a first terminal electrically connected to the second terminal of the first resistor, and a second terminal electrically connected to a ground reference voltage, and a second PMOS transistor having a source terminal electrically connected to the power supply voltage, a gate terminal electrically connected to the gate terminal of the first PMOS transistor, and a drain terminal electrically connected to the first branch of the current mirror. - View Dependent Claims (19)
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20. A circuit for generating an output voltage that is substantially constant despite process, voltage, or temperature variation in the circuit, the circuit comprising:
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an error amplifier having a first input, a second input, and an output, wherein the first input is electrically connected to a reference voltage, and the second input is electrically connected to an output node of the circuit via a feedback resistor, the feedback resistor including a first terminal electrically connected to the output node and a second terminal electrically connected to the second input; a pass transistor including a control electrode electrically connected to the output of the error amplifier, a first electrode electrically connected to a power supply voltage, and a second electrode electrically connected to the output node of the circuit; a current source configured to generate a reference current that changes when a resistance of the feedback resistor changes; a first branch of a current mirror electrically connected to the current source, the reference current flowing through the first branch; and a second branch of the current mirror electrically connected to the second terminal of the feedback resistor, wherein an output current that flows through the second branch and between the first and second terminals of the feedback resistor is based on (i) the reference current flowing through the first branch, and (ii) a mirror ratio of the current mirror, wherein the output node provides an output voltage of the circuit, and the current source includes; an operational amplifier including a first input, a second input, and a single-ended output, wherein the first input of the operational amplifier is electrically connected to the reference voltage, a first PMOS transistor having a source terminal electrically connected to the power supply voltage, and a gate terminal electrically connected to the single-ended output of the operational amplifier, a first resistor having a first terminal electrically connected to a drain terminal of the first PMOS transistor, and a second terminal electrically connected to the second input of the operational amplifier, a second resistor having a first terminal electrically connected to the second terminal of the first resistor, and a second terminal electrically connected to a ground reference voltage, and a second PMOS transistor having a source terminal electrically connected to the power supply voltage, a gate terminal electrically connected to the gate terminal of the first PMOS transistor, and a drain terminal electrically connected to the first branch of the current mirror.
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Specification