Current control circuit, class AB operational amplifier system and current control method
AssigneeAnpec Electronics Corporation
InventorsMing-Hung Chang, Che-Hung Lin
Life of this patent
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Abstract
A current control circuit for controlling a bias current of a class AB operational amplifier includes: a low current source, for generating a low bias current; a high current source, for generating a high bias current, which is greater than the low bias current; and a comparing and selecting unit, coupled to an output terminal of the class AB operational amplifier, for selecting one of the low bias current and the high bias current to output as the bias current according to an output voltage of the class AB OP.
Claims10
A current control circuit for controlling a bias current of a class AB operational amplifier (OP), comprising:
- a low bias current source, for generating a low bias current;
- a high bias current source, for generating a high bias current greater than the low bias current;
- and
- a comparing and selecting unit, coupled to an output terminal of the class AB OP, for selecting one of the low bias current and the high bias current to output as the bias current according to an output voltage of the class AB OP;
- wherein the comparing and selecting unit selects the low bias current to output as the bias current if an absolute value of a voltage difference between the output voltage and a quiescent voltage is less than a specific value, and selects the high bias current to output as the bias current if the absolute value of the voltage difference between the output voltage and the quiescent voltage is greater than the specific value.
A current control method for controlling a bias current of a class AB operational amplifier (OP), comprising:
- providing a low bias current and a high bias current, wherein the high bias current is greater than the low bias current;
- selecting one of the low bias current and the high bias current to output as the bias current according to an output voltage of the class AB OP;
- wherein the low bias current is selected to output as the bias current if an absolute value of a voltage difference between an output voltage and a quiescent voltage is less than a specific value, and the high bias current is selected to output as the bias current if the absolute value of the voltage difference between the output voltage and the quiescent voltage is greater than the specific value.
Dependencies are inferred from the claim text.