Magnetic Sensor Circuit and Portable Terminal Provided With Such Magnetic Sensor Circuit
First Claim
1. A magnetic sensor circuit, comprising:
- a magnetoelectric converting element generating an output voltage across a first terminal pair or a second terminal pair in accordance with applied magnetism;
a switch selecting circuit having a first switch status in which a power supply voltage is applied to said first terminal pair and an output voltage generated at said second terminal pair is output across a first output end and a second output end, and a second switch status in which the power supply voltage is applied to said second terminal pair and an output voltage generated at said first terminal pair is output across said first output end and said second output end;
an amplifying unit outputting to a first amplification output end a first amplified voltage obtained by amplifying the voltage of said first output end input to a first amplification input end, and outputting to a second amplification output end a second amplified voltage obtained by amplifying the voltage of said second output end input to a second amplification end;
a comparing unit comparing a first comparison voltage input to a first comparison input end with a second comparison voltage input to a second comparison input end and generating a comparison output when said first comparison voltage is different from said second comparison voltage;
a first capacitor provided between said first amplification output end and said first comparison input end;
a second capacitor provided between said second amplification output end and said second comparison input end;
a first switch circuit for applying a first reference voltage to said first comparison input end; and
a second switch circuit for applying a second reference voltage to said second comparison input end.
1 Assignment
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Accused Products
Abstract
A Hall element (10) outputs a Hall voltage generated at a first terminal pair (A, C) or a second terminal pair (B, D) to first and second output terminals by switching the voltage in a first status and a second status. Based on the voltages of the first and the second output terminals and a reference voltage, first and second capacitors (41, 42) are charged. Then, the voltages of the first and the second capacitors (41, 42) are compared, and a detection signal is obtained. Thus, a magnetic sensor circuit (1) which reduces influence of an element offset voltage of the Hall element (10) and also reduces influence of an input offset voltage generated at an amplifier (30), and a portable terminal provided with such magnetic sensor circuit (1) are provided.
54 Citations
18 Claims
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1. A magnetic sensor circuit, comprising:
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a magnetoelectric converting element generating an output voltage across a first terminal pair or a second terminal pair in accordance with applied magnetism; a switch selecting circuit having a first switch status in which a power supply voltage is applied to said first terminal pair and an output voltage generated at said second terminal pair is output across a first output end and a second output end, and a second switch status in which the power supply voltage is applied to said second terminal pair and an output voltage generated at said first terminal pair is output across said first output end and said second output end; an amplifying unit outputting to a first amplification output end a first amplified voltage obtained by amplifying the voltage of said first output end input to a first amplification input end, and outputting to a second amplification output end a second amplified voltage obtained by amplifying the voltage of said second output end input to a second amplification end; a comparing unit comparing a first comparison voltage input to a first comparison input end with a second comparison voltage input to a second comparison input end and generating a comparison output when said first comparison voltage is different from said second comparison voltage; a first capacitor provided between said first amplification output end and said first comparison input end; a second capacitor provided between said second amplification output end and said second comparison input end; a first switch circuit for applying a first reference voltage to said first comparison input end; and a second switch circuit for applying a second reference voltage to said second comparison input end. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A portable terminal, comprising:
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a battery power source; and a magnetic sensor circuit to which a power supply voltage of said battery power source is supplied as an operational voltage;
whereinsaid magnetic sensor circuit includes a magnetoelectric converting element generating an output voltage across a first terminal pair, or a second terminal pair in accordance with applied magnetism, a switch selecting circuit having a first switch status in which a power supply voltage is applied to said first terminal pair and an output voltage generated at said second terminal pair is output across a first output end and a second output end, and a second switch status in which the power supply voltage is applied to said second terminal pair and an output voltage generated at said first terminal pair is output across said first output end and said second output end, an amplifying unit outputting to a first amplification output end a first amplified voltage obtained by amplifying the voltage of said first output end input to a first amplification input end, and outputting to a second amplification output end a second amplified voltage obtained by amplifying the voltage of said second output end input to a second amplification end, a comparing unit comparing a first comparison voltage input to a first comparison input end with a second comparison voltage input to a second comparison input end and generating a comparison output when said first comparison voltage is different from said second comparison voltage, a first capacitor provided between said first amplification output end and said first comparison input end, a second capacitor provided between said second amplification output end and said second comparison input end, a first switch circuit for applying a first reference voltage to said first comparison input end, and a second switch circuit for applying a second reference voltage to said second comparison input end.
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Specification