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US 7,582,887 B1Granted
Optocoupler current transfer ratio temperature compensation method and apparatus
AssigneeEugene C. Lee
InventorEugene C. Lee
Life of this patent
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Abstract
Current transfer ratio temperature variation of an optocoupler is compensated by generation and summing of an optically generated current with a temperature dependent multiple of the optically generated current at the detector of the optocoupler.
Claims1
A method to compensate a current transfer ratio temperature variation of an optocoupler, comprising:
- (a) generating and summing of an optically generated current from a photo bipolar NPN transistor with a temperature dependent multiple of said optically generated current to produce a temperature compensated output current of the optocoupler;
- (b) said multiple of said optically generated current is realized with a common base current mirror circuit with emitter degeneration resistors integrated on a detector die of said optocoupler to produce the output current of said optocoupler;
- (c) said temperature compensation of said output current of said optocoupler is realized by a difference in temperature coefficients associated with different types of said emitter degeneration resistors integrated on said detector die of said optocoupler.
Dependencies are inferred from the claim text.