Semiconductor device having a sensor with the temperature compensation function

Claim 2

A semiconductor device comprising: amplifying means for receiving a sensor output signal from a sensor, amplifying the sensor output signal at a required temperature-independent amplification factor, and canceling an offset, reference signal producing means for producing a reference signal varying at a temperature coefficient equal to that of the sensor signal from said sensor, comparing means which compares a magnitude of an amplification output signal from said amplifying means with that of the reference signal from said reference signal producing means and outputs a required signal according to a comparison result, and constant voltage generating means for generating temperature-independent constant voltage to be supplied to said sensor, characterized in that said amplifying means, said reference signal producing means, said comparing means, and said constant voltage generating means are formed using a semiconductor layer provided on an insulating substrate.

Claim 3

The semiconductor device according to claim 1 , characterized in that said semiconductor layer is composed of a silicon thin film.

Claim 4

The semiconductor device according to claim 2 , characterized in that said silicon thin film is 30 nm to 1000 nm in thickness.

Claim 5

The semiconductor device according to claim 1 , 2 , or 3 , characterized in that said reference signal producing means is based on the previous measurement of a temperature coefficient of the sensor output signal of said sensor and produces a reference signal having an equal temperature coefficient.

Claim 6

The semiconductor device according to claim 4 , characterized in that said reference signal changes linearly with absolute temperature.

Claim 7

The semiconductor device according to claim 1 , characterized in that said amplifying means includes signal amplifying means which is composed of a plurality of operational amplifiers and amplifies said sensor output signal at a temperature-independent amplification factor, and offset compensating means for compensating for each offset of said plurality of operational amplifiers every predetermined period.

Claim 8

The semiconductor device according to claim 6 , characterized in that said operational amplifier includes a differential amplifying section for performing differential amplification on said sensor output signal and an offset compensating section for canceling an offset voltage of said differential amplifying section, and said offset compensating section receives an offset compensating signal according to an offset voltage of said differential amplifying section every predetermined period and cancels the offset voltage of said differential amplifying section in response to the offset compensation signal.

Claim 9

The semiconductor device according to claim 7 , characterized in that said offset compensation section further includes a capacitor, which holds a voltage for canceling an offset voltage of said differential amplifying section, and said capacitor periodically holds a voltage according to the offset voltage of said differential amplifying section, and said offset compensating section cancels the offset voltage of said differential amplifying section according to the held voltage.

Claim 10

The semiconductor device according to claim 1 , characterized in that said comparing means compares a magnitude of an amplification output signal from said amplifying means with those of two reference voltages, and the output is turned on/off according to a comparison result.

Claim 11

The semiconductor device according to claim 1 , characterized in that said comparing means computes a ratio of a magnitude of reference voltage between that of the amplification output signal from said amplifying means and outputs a digital signal according to the ratio.

Claim 12

The semiconductor device according to claim 1 , characterized in that said reference signal producing means includes at least a constant voltage source for generating temperature-independent constant voltage and a constant current source for generating constant current being directly proportional to absolute temperature and inversely proportional to the resistance of a reference resistor, and said reference signal producing means produces two reference voltage changing linearly with absolute temperature, according to the constant voltage generated in said constant voltage source and the constant current generated in said constant current source.

Claim 13

The semiconductor device according to claim 1 , characterized in that said reference signal producing means includes a first constant current source for generating a constant current being directly proportional to absolute temperature and inversely proportional to the resistance of reference resistor, a second constant current source which is connected in series to said first constant current source and generates constant current by applying temperature-independent constant voltage to voltage/current converting resistor. a third constant current source for generating constant current being fixed times larger than a different between a current of the second constant current source and a current of said first constant current source, and an upper limit reference voltage generating resistor and a lower limit reference voltage generating resistor which are connected in series to said third constant current source and are applied constant current from said third constant current source, and one or both of potentials generated in said upper limit reference voltage generating resistor and said lower limit reference voltage generating resistor are taken out as reference potentials.

Claim 14

The semiconductor device according to claim 12 , characterized in that said reference resistor, said voltage/current converting resistor, said upper limit reference voltage generating resistor, and said lower limit reference voltage generating resistor are equal to one another in temperature coefficient.

Claim 15

A semiconductor device comprising a sensor which converts a measured physical quantity to an electric signal and outputs the signal, which has a peculiar temperature coefficient, amplifying means which receives a sensor output signal of said sensor, amplifies the sensor output signal at a required amplification factor of temperature independence, and cancels an offset, reference signal producing means for producing a reference signal varying at a temperature coefficient equal to that of the sensor output signal of said sensor, comparing means for comparing a magnitude of the amplification output signal from said amplifying means with a magnitude of the reference signal from said reference signal producing means and for outputting a required signal according to a comparison result, and constant voltage generating means for generating temperature-independent constant voltage to be supplied to said sensor, characterized in that said amplifying means, said reference signal producing means, said comparing means, and said constant voltage generating means are formed using a semiconductor layer provided on an insulating substrate.

Claim 16

A semiconductor device comprising a sensor which converts a measured physical quantity to an electric signal and outputs the signal, which has a peculiar temperature coefficient, amplifying means which receives a sensor output signal of said sensor, amplifies the sensor output signal at a required amplification factor of temperature independence, and cancels an offset, reference signal producing means for producing a reference signal varying at a temperature coefficient equal to that of the sensor output signal of said sensor, comparing means for comparing a magnitude of the amplification output signal from said amplifying means with a magnitude of the reference signal from said reference signal producing means and for outputting a required signal according to a comparison result, and constant voltage generating means for generating temperature-independent constant voltage to be supplied to said sensor, characterized in that said amplifying means, said reference signal producing means, said comparing means, and said constant voltage generating means are formed using a semiconductor layer provided on an insulating substrate.

Claim 17

The semiconductor device according to claim 14 , characterized in that said semiconductor layer is a silicon thin film.

Claim 18

The semiconductor device according to claim 15 , characterized in that said silicon thin film is 30 nm to 1000 nm in thickness.

Claim 19

The semiconductor device according to claim 14 , 15 , or 16 , characterized in that a sensor output signal has a peculiar temperature coefficient in said sensor and the sensor output signal is produced in a linear function of absolute temperature.

Claim 20

The semiconductor device according to claim 14 , characterized in that said sensor is a magnetic sensor.

Claim 21

The semiconductor device according to claim 18 , characterized in that said magnetic sensor is a Hall element.

Claim 22

The semiconductor device according to claim 19 , characterized in that said Hall element has a magnetic sensitive part made of GaAs.

Claim 23

The semiconductor device according to claim 14 , characterized in that said reference signal producing means is based on the previous measurement of a temperature coefficient of the sensor output signal of said sensor and produces a reference signal having an equal temperature coefficient.

Claim 24

The semiconductor device according to claim 21 , characterized in that said reference signal changes linearly with absolute temperature.

Claim 25

The semiconductor device according to claim 14 , characterized in that said amplifying means includes signal amplifying means which is composed of a plurality of operational amplifies and amplifies a sensor output signal at a temperature-independent amplification factor, and offset compensating means for compensating for each offset of said plurality of operational amplifiers every predetermined period.

Claim 26

The semiconductor device according to claim 23 , characterized in that said operational amplifier includes a differential amplifying section for performing differential amplification on said sensor output signal and an offset compensating section for canceling an offset voltage of said differential amplifying section, and said offset compensating section receives an offset compensating signal according to an offset voltage of said differential amplifying section every predetermined period and cancels the offset voltage of said differential amplifying section in response to the offset compensation signal.

Claim 27

The semiconductor device according to claim 24 , characterized in that said offset compensation section further includes a capacitor, which holds voltage for canceling an offset voltage of said differential amplifying section, and said capacitor periodically holds a voltage according to the offset voltage of said differential amplifying section, and said offset compensating section cancels the offset voltage of said differential amplifying section according to the held voltage.

Claim 28

The semiconductor device according to claim 14 , characterized in that said comparing means compares a magnitude of an amplification output signal from said amplifying means with the magnitudes of two reference voltages, and the output is turned on/off according to a comparison result.

Claim 29

The semiconductor device according to claim 14 , characterized in that said comparing means computes a ratio of a magnitude of reference voltage between that of the amplification output signal from said amplifying means and outputs a digital signal according to the ratio.

Claim 30

The semiconductor device according to claim 14 , characterized in that said reference signal producing means includes at least a constant voltage source for generating temperature-independent constant voltage and a constant current source for generating constant current being directly proportional to absolute temperature and inversely proportional to the magnitude of a reference resistor, and said reference signal producing means produces two reference voltages changing linearly with absolute temperature, according to the constant voltage generated in said constant voltage source and the constant current generated in said constant current source.

Claim 31

The semiconductor device according to claim 14 , characterized in that said reference signal producing means includes a first constant current source for generating a constant current being directly proportional to absolute temperature and inversely proportional to a magnitude of reference resistor, a second constant current source which is connected in series to said first constant current source and generates constant current b applying temperature-independent constant voltage to a voltage/current converting resistor, a third constant current source for generating constant current being fixed times larger than a difference between a current of the second constant current source and a current of said first constant current source, and an upper limit reference voltage generating resistor and a lower limit reference voltage generating resistor which are connected in series to said third constant current source and are applied constant current from said third constant current source, and one or both of potentials generated in said upper limit reference voltage generating resistor and said lower limit reference voltage generating resistor are taken out as reference electric potentials.

Claim 32

The semiconductor device according to claim 29 , characterized in that said reference resistor, said voltage/current converting resistor, said upper limit reference voltage generating resistor, and said lower limit reference voltage generating resistor are equal to one another in temperature coefficient.