Low dropout voltage regulator
AssigneeNational Semiconductor Corporation
InventorRonald Neal Dow
Life of this patent
Estimating the term…
Abstract
A low dropout voltage regulator. The regulator comprises a bandgap reference circuit and first and second transistors coupled in parallel. The parallel transistors form the input of an operational amplifier, coupled to and providing substantially no load to the bandgap reference circuit. The bandgap reference circuit is coupled to the output of the integrated circuit low dropout voltage regulator. As a beneficial result, the bandgap reference works from a regulated output and has substantially no load. Consequently, the voltage output of the present invention is highly stable.
Claims19
An integrated circuit low dropout voltage regulator comprising:
- an output terminal for providing a regulated voltage output;
- first and second transistors having their collectors coupled to said output terminal;
- a first resistor having a first terminal coupled to the emitter of said first transistor;
- a second resistor having a first terminal coupled to a second terminal of said first resistor;
- a third resistor having a first terminal coupled to said second terminal of said second resistor;
- a third transistor having a base terminal coupled to the emitter terminal of said second transistor and coupled to a second terminal of said third resistor;
- a fourth transistor having a base terminal coupled to said second terminal of said first resistor;
- and
- wherein said third and fourth transistors are coupled in parallel.
A low dropout voltage regulator comprising:
- a proportional to absolute temperature (PTAT) circuit comprising a bipolar transistor for providing a substantially constant current and having a base, an emitter, and a collector;
- a current sourcing bipolar transistor comprising a base, an emitter, and a collector coupled to said base of said current sourcing bipolar transistor and coupled to said collector of said bipolar transistor;
- a first biasing bipolar transistor comprising a base coupled to said base of said current sourcing bipolar transistor, an emitter, and a collector;
- a second biasing bipolar transistor comprising a base coupled to said base of said current sourcing bipolar transistor, an emitter, and a collector;
- a third biasing bipolar transistor comprising a base coupled to said base of said current sourcing bipolar transistor, an emitter, and a collector;
- and
- a bandgap voltage generation circuit for generating a bandgap voltage, wherein said first, second, and third biasing transistors bias said bandgap voltage generation circuit.
A low dropout voltage regulator comprising:
- a proportional to absolute temperature (PTAT) circuit comprising a current sourcing bipolar transistor comprising a base, an emitter, and a collector;
- a voltage clamping bipolar transistor comprising a base coupled to a separately derived voltage, an emitter coupled to said collector of said current sourcing bipolar transistor, and a collector coupled to ground;
- a current mirror circuit coupled to said collector of said current sourcing bipolar transistor;
- and
- a bandgap voltage generation circuit for generating a bandgap voltage, wherein said current mirror circuit sources current to said bandgap voltage generation circuit.
Dependencies are inferred from the claim text.