Variable current source
First Claim
1. A variable current source for providing a selected output current that is highly temperature stabilized to a current output terminal to which a selected load is connected, said variable current source comprising:
- a reference current generator for generating a reference current of a constant value that is substantially insusceptible to the influence of temperature;
a plurality of reference resistance elements and a further resistance element for compensation use which are simultaneously formed on a common substrate so as to experience a common temperature;
an auxiliary reference voltage generator wherein the output of the reference current generator is connected with a first terminal of said further metal resistance element to generate an auxiliary reference voltage across said further resistance element;
a plurality of switches respectively connected in series with the plurality of reference resistance elements to form a respective plurality of series circuits;
anda voltage-to-current converter which is connected to the series circuits and which, when one or more of said switches are turned ON, converts the auxiliary reference voltage to a current corresponding to the resistance value of the respective reference resistance element(s) connected to each of the switches turned ON,wherein said selected output current that is output from said current output terminal of said variable current source has said highly tremperature stabilized output current for any combination of said switches being ON.
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Accused Products
Abstract
A plurality of metal resistance elements and a metal resistance element for compensation use are formed on a common substrate and placed under the same temperature condition. A reference current is applied to the metal resistance element for compensation use to yield an auxiliary reference voltage. A plurality of switches are individually connected in series to the reference metal resistance elements and the auxiliary reference voltage is provided to the series circuits to selectively control the switches, thereby obtaining various currents.
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Citations
6 Claims
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1. A variable current source for providing a selected output current that is highly temperature stabilized to a current output terminal to which a selected load is connected, said variable current source comprising:
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a reference current generator for generating a reference current of a constant value that is substantially insusceptible to the influence of temperature; a plurality of reference resistance elements and a further resistance element for compensation use which are simultaneously formed on a common substrate so as to experience a common temperature; an auxiliary reference voltage generator wherein the output of the reference current generator is connected with a first terminal of said further metal resistance element to generate an auxiliary reference voltage across said further resistance element; a plurality of switches respectively connected in series with the plurality of reference resistance elements to form a respective plurality of series circuits; and a voltage-to-current converter which is connected to the series circuits and which, when one or more of said switches are turned ON, converts the auxiliary reference voltage to a current corresponding to the resistance value of the respective reference resistance element(s) connected to each of the switches turned ON, wherein said selected output current that is output from said current output terminal of said variable current source has said highly tremperature stabilized output current for any combination of said switches being ON. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification