Tunable constant current source with temperature and power supply compensation
First Claim
1. A tunable constant current source having temperature and power supply compensation, said tunable constant current source comprising:
- a voltage regulator operable to provide a substantially constant bias voltage Vb, said voltage regulator includes a gross temperature compensation circuit operable to switch between one of a plurality of branches depending upon an operating temperature of a circuit employing said tunable constant current source to maintain said bias voltage VB substantially constant;
a differential amplifier operable to receive said bias voltage VB and maintain a load voltage VL substantially equal to said bias voltage VB by way of a negative feedback;
a current source operable to generate a substantially constant current IREF from said differential amplifier; and
a compensating load operable to vary with temperature changes to maintain said current IREF substantially constant, wherein said tunable constant current source may operate in a supply voltage range between about 0.5 volts to about 1.8 volts.
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Accused Products
Abstract
A tunable constant current source having temperature and power supply compensation is provided. The tunable constant current source includes a voltage regulator, a differential amplifier, a current source and a compensating load. The voltage regulator provides a substantially constant bias voltage VB. The differential amplifier receives the bias voltage VB and maintains a load voltage VL substantially equal to the bias voltage VB by way of a negative feedback. The current source generates a substantially constant current IREF from the differential amplifier. The compensating load varies with temperature changes to maintain the current IREF substantially constant, whereby the tunable constant current source may operate in a supply voltage range between about 0.5 volts to about 1.8 volts.
32 Citations
11 Claims
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1. A tunable constant current source having temperature and power supply compensation, said tunable constant current source comprising:
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a voltage regulator operable to provide a substantially constant bias voltage Vb, said voltage regulator includes a gross temperature compensation circuit operable to switch between one of a plurality of branches depending upon an operating temperature of a circuit employing said tunable constant current source to maintain said bias voltage VB substantially constant;
a differential amplifier operable to receive said bias voltage VB and maintain a load voltage VL substantially equal to said bias voltage VB by way of a negative feedback;
a current source operable to generate a substantially constant current IREF from said differential amplifier; and
a compensating load operable to vary with temperature changes to maintain said current IREF substantially constant, wherein said tunable constant current source may operate in a supply voltage range between about 0.5 volts to about 1.8 volts. - View Dependent Claims (2, 3, 4, 5)
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6. A voltage regulator for use in a constant current source, said voltage regulator comprising:
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a negative feedback circuit operable to generate a substantially constant bias voltage VB;
a gross temperature compensation circuit forming a portion of said negative feedback circuit and having a plurality of decodable branches with one of said plurality of branches selected to operate with said negative feedback circuit based upon an operating temperature of a circuit employing said voltage regulator;
a bias circuit operable to bias said negative feedback circuit with a reference voltage REFP; and
a temperature compensation circuit operable to vary said reference voltage REFP during slight variations in said operating temperature of said circuit. - View Dependent Claims (7, 8, 9, 10, 11)
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Specification