BAND GAP REFERENCE VOLTAGE CIRCUIT
First Claim
1. A band gap reference voltage circuit for supplying a reference voltage constant with temperature, comprising:
- a first power source configured to generate a first voltage;
a second power source powered by the first voltage to generate a second voltage independent of fluctuations of the first voltage from the first power source;
a first temperature sensor having a first temperature characteristic;
a second temperature sensor having a second temperature characteristic;
a first current mirror circuit powered by the second voltage to drive the first temperature sensor to generate a first sensor voltage across the first temperature sensor and caused by the first sensor voltage to flow a first sensor current through the first current mirror circuit;
a second current mirror circuit powered by the second voltage to drive the second temperature sensor via a resistor to generate a second sensor voltage across the second temperature sensor and caused by a sum of the second sensor voltage and a voltage appearing across the resistor to flow a second sensor current having a temperature dependency polarity through the second current mirror circuit;
a current coupler configured to use one of the first and second sensor currents as a reference current to generate the reference voltage having the same temperature dependency polarity as the reference current; and
a polarity offset circuit configured to provide the reference voltage with the opposite temperature dependency polarity to make the voltage reference substantially independent of temperature,wherein the second power source is responsive to a difference between the first sensor current and the second sensor current to change the second voltage such that the first and second sensor currents become substantially equal, andwherein when the first and second sensor currents are substantially equal, the resistor produces thereacross a voltage substantially equal to a difference between the first and second sensor voltage and having a temperature dependency polarity determined by the first and second temperature characteristics of the first and second temperature sensors, which polarity determines the temperature dependency polarity of the reference current.
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Accused Products
Abstract
Provided is a band gap reference voltage circuit having an improved power supply rejection ratio. Owing to a voltage supply circuit (51), a power supply voltage (V5) does not depend on variation of a power supply voltage (Vdd). A voltage (V3−V2) which is generated across a resistor (41) and has a positive temperature coefficient is determined based not on the power supply voltage (Vdd) but on the power supply voltage (V5), and hence the voltage (V3−V2) does not depend on the variation of the power supply voltage (Vdd). As a result, the power supply rejection ratio of the band gap reference voltage circuit is improved.
18 Citations
16 Claims
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1. A band gap reference voltage circuit for supplying a reference voltage constant with temperature, comprising:
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a first power source configured to generate a first voltage; a second power source powered by the first voltage to generate a second voltage independent of fluctuations of the first voltage from the first power source; a first temperature sensor having a first temperature characteristic; a second temperature sensor having a second temperature characteristic; a first current mirror circuit powered by the second voltage to drive the first temperature sensor to generate a first sensor voltage across the first temperature sensor and caused by the first sensor voltage to flow a first sensor current through the first current mirror circuit; a second current mirror circuit powered by the second voltage to drive the second temperature sensor via a resistor to generate a second sensor voltage across the second temperature sensor and caused by a sum of the second sensor voltage and a voltage appearing across the resistor to flow a second sensor current having a temperature dependency polarity through the second current mirror circuit; a current coupler configured to use one of the first and second sensor currents as a reference current to generate the reference voltage having the same temperature dependency polarity as the reference current; and a polarity offset circuit configured to provide the reference voltage with the opposite temperature dependency polarity to make the voltage reference substantially independent of temperature, wherein the second power source is responsive to a difference between the first sensor current and the second sensor current to change the second voltage such that the first and second sensor currents become substantially equal, and wherein when the first and second sensor currents are substantially equal, the resistor produces thereacross a voltage substantially equal to a difference between the first and second sensor voltage and having a temperature dependency polarity determined by the first and second temperature characteristics of the first and second temperature sensors, which polarity determines the temperature dependency polarity of the reference current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for supplying a reference voltage constant with temperature, comprising:
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generating a first voltage; powered by the first voltage, generating a second voltage independent of fluctuations of the first voltage; powered by the second voltage, driving a first temperature sensor having a first temperature characteristic to generate a first sensor voltage across the first temperature sensor; caused by the first sensor voltage, flowing a first sensor current; powered by the second voltage, driving, via a resistor, a second temperature sensor having a second temperature characteristic to generate a second sensor voltage across the second temperature sensor; caused by a sum of the second sensor voltage and a voltage appearing across the resistor, flowing a second sensor current having a temperature dependency polarity; using one of the first and second sensor currents as a reference current, generating the reference voltage having the same temperature dependency polarity as the reference current; providing the reference voltage with the opposite temperature dependency polarity to make the voltage reference substantially independent of temperature; and responsive to a difference between the first sensor current and the second sensor current, changing the second voltage such that the first and second sensor currents become substantially equal, wherein when the first and second sensor currents are substantially equal, the resistor produces thereacross a voltage substantially equal to a difference between the first and second sensor voltage and having a temperature dependency polarity determined by the first and second temperature characteristics of the first and second temperature sensors, which polarity determines the temperature dependency polarity of the reference current.
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16. A band gap reference voltage circuit for supplying a reference voltage constant with temperature, comprising:
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means for generating a first voltage; means powered by the first voltage to generate a second voltage independent of fluctuations of the first voltage; means powered by the second voltage to drive a first temperature sensor having a first temperature characteristic to generate a first sensor voltage across the first temperature sensor; means caused by the first sensor voltage to flow a first sensor current; means powered by the second voltage to drive, via a resistor, a second temperature sensor having a second temperature characteristic to generate a second sensor voltage across the second temperature sensor; means caused by a sum of the second sensor voltage and a voltage appearing across the resistor to flow a second sensor current having a temperature dependency polarity; means using one of the first and second sensor currents as a reference current to generate the reference voltage having the same temperature dependency polarity as the reference current; and means for providing the reference voltage with the opposite temperature dependency polarity to make the voltage reference substantially independent of temperature, wherein said means for generating the second voltage is responsive to a difference between the first sensor current and the second sensor current to change the second voltage such that the first and second sensor currents become substantially equal, and wherein when the first and second sensor currents are substantially equal, the resistor produces thereacross a voltage substantially equal to a difference between the first and second sensor voltage and having a temperature dependency polarity determined by the first and second temperature characteristics of the first and second temperature sensors, which polarity determines the temperature dependency polarity of the reference current.
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Specification