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US 8,008,966 B2Granted
Start-up circuit for generating bandgap reference voltage
AssigneeDongbu HitekCo., Ltd
InventorEun Sang Cho
Life of this patent
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Abstract
Disclosed is a start-up circuit that can stably and rapidly start up a bandgap reference voltage generating circuit when the bandgap reference voltage generating circuit is switched from a sleep mode to an operation mode, even if a difference in electrical characteristic, such as DC offset or the like, occurs due to, e.g, a physical difference between input transistors of an operational amplifier.
Claims8
A start-up circuit which is used in a bandgap reference voltage generating circuit, the start-up circuit comprising:
- a first PMOS transistor having a drain connected to a power supply terminal, and a source and a gate connected with each other;
- a first NMOS transistor having a drain connected to the source of the first PMOS transistor and a gate connected to a bandgap output terminal;
- a second NMOS transistor having a drain connected to a source of the first NMOS transistor, a source connected to a ground terminal, and a gate to which a first mode signal is applied;
- a third NMOS transistor having a drain connected to an output terminal of an operational amplifier and a gate connected to the drain of the first NMOS transistor;
- and
- a fourth NMOS transistor having a source connected to the ground terminal, a drain connected to a source of the third NMOS transistor, and a gate to which the first mode signal is applied.
3 more elements
Dependencies are inferred from the claim text.