Current sensing circuit with automatic offset compensation
First Claim
1. A current sensing circuit with automatic offset compensation comprising:
- (1) a current sensing resistor;
(2) a difference amplifier with current sensing resistor voltage input to its voltage measuring input terminal, and a reference voltage input to its reference voltage terminal;
(3) a small bias voltage circuit which adds a small bias voltage to the current sensing resistor voltage input to the difference amplifier voltage measuring input terminal to make difference amplifier output voltage larger; and
(4) a measurement circuit to measure difference amplifier output voltage, compensate the reference voltage input to the difference amplifier reference voltage terminal such that difference amplifier output is compensated to 0V when current sensing resistor current is zero, and also to measure current flowing in the current sensing resistor from the output voltage of the difference amplifier.
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Accused Products
Abstract
The current sensing circuit with automatic offset compensation is provided with a current sensing resistor, a difference amplifier which inputs this current sensing resistor voltage at its voltage measuring input terminal and inputs a reference voltage at its reference voltage terminal, and a measuring circuit which determines the current flowing in the current sensing resistor from the difference amplifier output voltage. The current sensing circuit adds a small bias voltage to the current sensing resistor voltage and inputs it to the voltage measuring input terminal to increase difference amplifier output voltage. The measuring circuit measures difference amplifier output voltage and compensates the reference voltage input to the difference amplifier reference voltage terminal to compensate difference amplifier output to 0V when current sensing resistor current is zero.
29 Citations
12 Claims
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1. A current sensing circuit with automatic offset compensation comprising:
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(1) a current sensing resistor; (2) a difference amplifier with current sensing resistor voltage input to its voltage measuring input terminal, and a reference voltage input to its reference voltage terminal; (3) a small bias voltage circuit which adds a small bias voltage to the current sensing resistor voltage input to the difference amplifier voltage measuring input terminal to make difference amplifier output voltage larger; and (4) a measurement circuit to measure difference amplifier output voltage, compensate the reference voltage input to the difference amplifier reference voltage terminal such that difference amplifier output is compensated to 0V when current sensing resistor current is zero, and also to measure current flowing in the current sensing resistor from the output voltage of the difference amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification