Voltage regulator with improved power supply rejection ratio characteristics and narrow response band
First Claim
1. A voltage regulator comprising:
- first and second power supply terminals;
an output terminal;
a reference voltage generating circuit adapted to generate a reference voltage;
a drive transistor connected between said first power supply terminal and said output terminal, said drive transistor having a control terminal;
a voltage divider connected between said output terminal and said second power supply terminal, said voltage divider adapted to generate a feedback voltage between voltages at said output terminal and said first power supply terminal;
a differential amplifier having a first input connected to said voltage divider, a second input connected to said reference voltage generating circuit and an output connected to the control terminal of said drive transistor, said differential amplifier adapted to generate an error voltage in accordance with said feedback voltage and said reference voltage and transmit said error voltage to the control terminal of said drive transistor;
an oscillation preventing capacitor connected between the control of said drive transistor and said output terminal; and
a capacitor connected between said first power supply terminal and the first input of said differential amplifier.
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Accused Products
Abstract
In a voltage regulator, a reference voltage generating circuit generates a reference voltage. A drive transistor is connected between a first power supply terminal and an output terminal and has a control terminal. A voltage divider generates a feedback voltage which is an intermediate voltage between voltages at the output terminal and a first power supply terminal. A differential amplifier generates an error voltage in accordance with the feedback voltage of the voltage divider and the reference voltage, and transmits it to the control terminal of the drive transistor. An oscillation preventing capacitor is connected between the control of the drive transistor and the output terminal. A capacitor is connected between the first power supply terminal and the first input of the differential amplifier.
20 Citations
11 Claims
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1. A voltage regulator comprising:
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first and second power supply terminals;
an output terminal;
a reference voltage generating circuit adapted to generate a reference voltage;
a drive transistor connected between said first power supply terminal and said output terminal, said drive transistor having a control terminal;
a voltage divider connected between said output terminal and said second power supply terminal, said voltage divider adapted to generate a feedback voltage between voltages at said output terminal and said first power supply terminal;
a differential amplifier having a first input connected to said voltage divider, a second input connected to said reference voltage generating circuit and an output connected to the control terminal of said drive transistor, said differential amplifier adapted to generate an error voltage in accordance with said feedback voltage and said reference voltage and transmit said error voltage to the control terminal of said drive transistor;
an oscillation preventing capacitor connected between the control of said drive transistor and said output terminal; and
a capacitor connected between said first power supply terminal and the first input of said differential amplifier. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A voltage regulator comprising:
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first and second power supply terminals;
an output terminal;
a reference voltage generating circuit adapted to generate a reference voltage;
a drive transistor connected between said first power supply terminal and said output terminal, said drive transistor having a control terminal;
a voltage divider connected between said output terminal and said second power supply terminal, said voltage divider adapted to generate a feedback voltage between voltages at said output terminal and said first power supply terminal;
a differential amplifier having a first input connected to said voltage divider, a second input connected to said reference voltage generating circuit and an output connected to the control terminal of said drive transistor, said differential amplifier adapted to generate an error voltage in accordance with said feedback voltage and said reference voltage and transmit said error voltage to the control terminal of said drive transistor;
an oscillation preventing capacitor connected between the control of said drive transistor and said output terminal;
a plurality of capacitors associated with switches, connected between said first power supply terminal and the first input of said differential amplifier; and
a control circuit connected to said plurality of capacitors and adapted to select said plurality of capacitors in accordance with a resistance of an external load connected to said output terminal. - View Dependent Claims (8, 9, 10, 11)
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Specification