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US 8,138,743 B2Granted
Band-gap reference voltage source circuit with switchable bias voltage
AssigneeElpida Memory, Inc.
InventorAkira Ide
Life of this patent
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Abstract
A band-gap reference voltage source circuit is constituted of a diode-pair circuit connected to a reference voltage output terminal, a first differential amplifier including a first transistor and a first operational amplifier, and a second differential amplifier including a second transistor and a second operational amplifier. The second differential amplifier operates based on a bias voltage, which is lower than a predetermined voltage, so as to forcedly pull up the level of the reference voltage output terminal via the second transistor before the first differential amplifier starts to pull up the level of the reference voltage output terminal up to the predetermined voltage via the first transistor.
Claims20
A band-gap reference voltage source circuit comprising:
- a diode-pair circuit including a first diode whose cathode is connected to a ground potential and whose anode is connected to a first voltage detection terminal, a second diode whose junction area differs from a junction area of the first diode and whose cathode is connected to the ground potential, a first resistor which is connected between the first voltage detection terminal and a reference voltage output terminal, a second resistor which is connected between a second voltage detection terminal and the reference voltage output terminal, and a third resistor which is connected between the second voltage detection terminal and an anode of the second diode;
- a first differential amplifier of an open-drain output type, which is constituted of a first first-conduction-type transistor whose source is connected to a power-supply voltage and whose drain is connected to the reference voltage output terminal, and a first operational amplifier whose noninverting input terminal is connected to the first voltage detection terminal, whose inverting input terminal is connected to the second voltage detection terminal, and whose output terminal is connected to a gate of the first first-conduction-type transistor;
- and
- a second differential amplifier of an open-drain output type, which is constituted of a second first-conduction-type transistor whose source is connected to the power-supply voltage and whose drain is connected to the reference voltage output terminal, and a second operational amplifier whose noninverting input terminal is disconnected from each of the first and second voltage detection terminals and is connected to a first bias voltage which is lower than a predetermined voltage at the reference voltage output terminal, whose inverting input terminal is connected to the reference voltage output terminal, and whose output terminal is connected to a gate of the second first-conduction-type transistor.
1 more element
A band-gap reference voltage source circuit which generates and outputs a predetermined voltage to a reference voltage output terminal irrespective of a power-supply voltage, comprising:
- a bias generator which is connected to the power-supply voltage so as to generate a first bias voltage lower than the predetermined voltage;
- a diode-pair circuit in which a pair of resistors having different resistances is connected in series with a pair of diodes and is connected in parallel with the reference voltage output terminal;
- a first first-conduction-type transistor whose source is connected to the power-supply voltage and whose drain is connected to the reference voltage output terminal;
- a second first-conduction-type transistor whose source is connected to the power-supply voltage and whose drain is connected to the reference voltage output terminal;
- a first differential amplifier whose first and second input terminals are connected to nodes between the resistors and the diodes in the diode-pair circuit;
- and
- a second differential amplifier whose first input terminal is disconnected from each of the nodes and is connected to the bias generator and whose second input terminal is connected to the reference voltage output terminal;
- wherein a gate of the first first-conduction-type transistor is connected to an output terminal of the first differential amplifier,
- a gate of the second first-conduction-type transistor is connected to an output terminal of the second differential amplifier,
- the second differential amplifier operates based on the first bias voltage,
- the first differential amplifier operates when the second first-conduction-type transistor allows a current to flow through the diode-pair circuit,
- so that the predetermined voltage is applied to the reference voltage output terminal when the second first-conduction-type transistor allows the current to flow through the diode-pair circuit.
9 more elements
A device comprising:
- a band-gap regulator generating at an output terminal thereof a band-gap voltage, the band-gap regulator comprising a first differential amplifier that includes first and second input nodes and a first output node;
- a bias voltage generator generating a bias voltage that is different from the band-gap voltage;
- and
- a second differential amplifier including third and fourth input nodes and a second output node, the third input node being separated from each of the first and second input nodes of the first differential amplifier and being connected to the bias voltage generator to receive the bias voltage, and the fourth input node and the second output node being electrically connected in common to the output terminal of the band-gap regulator.
1 more element
Dependencies are inferred from the claim text.