VOLTAGE-CONTROLLED CURRENT SOURCE
First Claim
1. A voltage-controlled current source for receiving a control voltage and using the control voltage to control an output current, the voltage-controlled current source comprising:
- an operational amplifier having a first input terminal for receiving the control voltage;
a first transistor, wherein a gate terminal of the first transistor is coupled to an output terminal of the operational amplifier and a first source/drain terminal of the first transistor is coupled to a second input terminal of the operational amplifier;
a resistor, wherein one terminal of the resistor is coupled to a first voltage line and the other terminal of the resistor is coupled to the first source/drain terminal of the first transistor; and
a current mirror having a reference side input terminal and an output side output terminal, wherein the reference side output terminal is coupled to a second source/drain terminal of the first transistor and the output side output terminal outputs the output current.
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Accused Products
Abstract
A voltage-controlled current source (VCCS) is provided. The VCCS controls an output current according to a controlling voltage. The VCCS includes an operational amplifier (OP-amplifier), a transistor, a resistor and a current mirror. The present invention utilizes the characteristics of the OP-amplifier to compensate for the voltage difference between the gate and the source of the transistor so that the resulting terminal voltage on the resistor is equal to the input control voltage. Therefore, the VCCS of the present invention can reduce the factors including process drift, fluctuation in the DC voltage source or the output current that can affect the terminal voltage difference of the resistor and hence the accuracy of the output current.
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Citations
37 Claims
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1. A voltage-controlled current source for receiving a control voltage and using the control voltage to control an output current, the voltage-controlled current source comprising:
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an operational amplifier having a first input terminal for receiving the control voltage;
a first transistor, wherein a gate terminal of the first transistor is coupled to an output terminal of the operational amplifier and a first source/drain terminal of the first transistor is coupled to a second input terminal of the operational amplifier;
a resistor, wherein one terminal of the resistor is coupled to a first voltage line and the other terminal of the resistor is coupled to the first source/drain terminal of the first transistor; and
a current mirror having a reference side input terminal and an output side output terminal, wherein the reference side output terminal is coupled to a second source/drain terminal of the first transistor and the output side output terminal outputs the output current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A voltage-controlled current source for receiving a control voltage and using the control voltage to control an output current, the voltage-controlled current source comprising:
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an operational amplifier having a first input terminal for receiving the control voltage;
a first transistor, wherein a gate terminal of the first transistor is coupled to an output terminal of the operational amplifier and a first source/drain terminal of the first transistor is coupled to a second input terminal of the operational amplifier;
a second transistor, wherein a gate terminal of the second transistor is coupled to the output terminal of the operational amplifier and a first source/drain terminal of the second transistor outputs the output current;
a resistor, wherein one terminal of the resistor is coupled to a first voltage line and the other terminal of the resistor is coupled to the first source/drain terminal of the first transistor; and
a current mirror having a reference side input terminal and an output side output terminal, wherein the reference side output terminal is coupled to a second source/drain terminal of the first transistor and the output side output terminal is coupled to a second source/drain terminal of the second transistor. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A voltage-controlled current source for receiving a first control voltage and a second control voltage and using the first control voltage and the second control voltage to control a first output current and a second output current, respectively, the voltage-controlled current source comprising:
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a first operational amplifier, wherein a first input terminal of the first operational amplifier receives the first control voltage;
a second operational amplifier, wherein a first input terminal of the second operational amplifier receives the second control voltage;
a first transistor, wherein a gate terminal of the first transistor is coupled to an output terminal of the first operational amplifier and a first source/drain terminal of the first transistor is coupled to a second input terminal of the first operational amplifier;
a second transistor, wherein a gate terminal of the second transistor is coupled to an output terminal of the second operational amplifier and a first source/drain terminal of the second transistor is coupled to a second input terminal of the second operational amplifier;
a resistor, wherein one terminal of the resistor is coupled to the first source/drain terminal of the first transistor and the other terminal of the resistor is coupled to the first source/drain terminal of the second transistor;
a first current mirror having a reference side output terminal and an output side output terminal, wherein the reference side output terminal of the first current mirror is coupled to a second source/drain terminal of the first transistor and the output side output terminal of the first current mirror outputs the first output current; and
a second current mirror having a reference side output terminal and an output side output terminal, wherein the reference side output terminal of the second current mirror is coupled to a second source/drain terminal of the second transistor and the output side output terminal of the second current mirror outputs the second output current. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A voltage-controlled current source for receiving a first control voltage and a second control voltage and using the first control voltage and the second control voltage to control a first output current and a second output current, respectively, the voltage-controlled current source comprising:
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a first operational amplifier, wherein a first input terminal of the first operational amplifier receives the first control voltage;
a second operational amplifier, wherein a first input terminal of the second operational amplifier receives the second control voltage;
a first transistor, wherein a gate terminal of the first transistor is coupled to an output terminal of the first operational amplifier and a first source/drain terminal of the first transistor is coupled to a second input terminal of the first operational amplifier;
a second transistor, wherein a gate terminal of the second transistor is coupled to the output terminal of the first operational amplifier and a first source/drain terminal of the second transistor outputs the first output current;
a third transistor, wherein a gate terminal of the third transistor is coupled to an output terminal of the second operational amplifier and a first source/drain terminal of the third transistor is coupled to a second input terminal of the second operational amplifier;
a fourth transistor, wherein a gate terminal of the fourth transistor is coupled to the output terminal of the second operational amplifier and a first source/drain terminal of the fourth transistor outputs the second output current;
a resistor, wherein one terminal of the resistor is coupled to the first source/drain terminal of the first transistor and the other terminal of the resistor is coupled to the first source/drain terminal of the third transistor;
a first current mirror having a reference side output terminal and an output side output terminal, wherein the reference side output terminal of the first current mirror is coupled to a second source/drain terminal of the first transistor and the output side output terminal of the first current mirror is coupled to a second source/drain terminal of the second transistor; and
a second current mirror having a reference side output terminal and an output side output terminal, wherein the reference side output terminal of the second current mirror is coupled to a second source/drain terminal of the third transistor and the output side output terminal of the second current mirror is coupled to a second source/drain terminal of the fourth transistor. - View Dependent Claims (25, 26, 27, 28)
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29. A voltage-controlled current source for receiving a first control voltage and a second control voltage and using the first control voltage and the second control voltage to control a first output current and a second output current, respectively, the voltage-controlled current source comprising:
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a first operational amplifier, wherein a first input terminal of the first operational amplifier receives the first control voltage;
a second operational amplifier, wherein a first input terminal of the second operational amplifier receives the second control voltage;
a first current mirror having a reference side and an output side for controlling the reference current from the reference side output terminal according to the reference side control terminal such that the output side output terminal outputs an output current corresponding to the reference current, wherein the reference side control terminal of the first current mirror is coupled to an output terminal of the first operational amplifier and the output side output terminal of the first current mirror outputs the first output current;
a second current mirror having a reference side and an output side for controlling the reference current from the reference side output terminal according to the reference side control terminal such that the output side output terminal outputs an output current corresponding to the reference current, wherein the reference side control terminal of the second current mirror is coupled to an output terminal of the second operational amplifier and the output side output terminal of the second current mirror outputs the second output current;
a resistor, wherein one side of the resistor is coupled to a second input terminal of the first operational amplifier and the reference side output terminal of the first current mirror and the other side of the resistor is coupled to a second input terminal of the second operational amplifier and the reference side output terminal of the second current mirror. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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Specification