Patent ID: 6861839

Claim:
A magnetic field sensor characterized in comprising: a magnetic field element for outputting a signal in accordance with an applied magnetic field strength to an output terminal; a switch circuit for inputting the signal of said output terminal of said magnetic field element and for outputting a signal selected by a signal comprising first and second phases given from the outside of said switch circuit, wherein said switch circuit comprises first and second memory elements, in said first phase of said signal given from the outside of said switch circuit, the output voltage of the output terminal of said magnetic field element is stored in said first memory element and the voltage stored in said second memory element is given to said amplifier and, in said second phase, the voltage stored in said first memory element is given to said amplifier and the voltage of the output terminal of said magnetic field element is stored in said second memory element; said amplifier wherein at least one input terminal is connected to the output terminal of said switch circuit and a voltage gained by amplifying the signal of this input terminal is outputted to an output terminal; a third memory element of which one end is connected to said output terminal of said amplifier; a signal output terminal connected to said other terminal of said third memory element; and a switch of which one end is connected to the other end of said third memory element and which carries out opening and closing operations by means of said signal which comprises the first and the second phases given from the outside of said switch, wherein said switch closes in said first phase so that said third memory element stores an output voltage of said amplifier and said switch opens in said second phase so that a sum of said voltage stored in said third memory element and an output voltage of said amplifier is outputted to said signal output terminal.