Semiconductor device

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2015-063255, filed on Mar. 25, 2015, the disclosure of which is incorporated by reference herein.

The present disclosure relates to a semiconductor device.

For example, in an analog-digital (AD) converter, a digital-analog (DA) converter, and the like, a resistance voltage dividing circuit including a serial resistance section in which plural resistance elements are connected in series, and a constant-current source which is connected to each of one end and the other end of the serial resistance section, is used (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2003-078415).

FIG. 8 illustrates an example of a resistance voltage dividing circuit 100 . The resistance voltage dividing circuit 100 includes a serial resistance section 110 in which resistance elements R 1 to R 12 are connected in series, and constant-current sources I 1 and I 2 . The constant-current source I 1 is a constant-current source of a so-called discharge type which discharges a bias current Ibias 1 . The constant-current source I 1 supplies a power-supply voltage VCC from one end thereof, and the other end thereof is connected to one end of the serial resistance section 110 . Further, the constant-current source I 2 is a constant-current source of a so-called sink type which sinks a bias current Ibias 2 , and has one end being connected to the other end of the serial resistance section 110 and the other end being grounded. Further, a voltage Vin is input to a connection point between the resistance element R 6 and the resistance element R 7 .

In the resistance voltage dividing circuit 100 configured in this manner, a divided voltage is output from each connection point among the resistance elements R 1 to R 12 . In a case in which each resistance value of the resistance elements R 1 to R 12 is set to r, for example, a voltage of Vin+Ibias 1 ×r×n (n=5 to 1) is output from each connection point among the resistance element R 1 to R 6 . Further, a voltage of Vin−Ibias 2 ×r×n (n=1 to 5) is output from each connection point among the resistance element R 7 to R 12 . Further, the voltage Vin is output from the connection point between the resistance element R 6 and the resistance element R 7 .

In a semiconductor device including the resistance voltage dividing circuit 100 described above, when operating the device, it is important for the bias current Ibias 1 discharged by the constant-current source I 1 and the bias current Ibias 2 sunk by the constant-current source I 2 to be equal.

For example, in a case in which the bias current Ibias 1 and the bias current Ibias 2 are different, current flows out to an input terminal side to which the voltage Yin is input, and thus, is such case, the device may not properly operate.

Further, for example, in a case in which the bias current Ibias 1 and the bias current Ibias 2 are different, a degree of rise in potential from the voltage Yin in each connection point among the resistance element R 1 to R 6 and a degree of drop in potential from the voltage Yin in each connection point among the resistance element R 7 to the resistance element R 12 becomes different from each other, and thus, is such case, the device may not properly operate.

However, in JP-A No. 2003-078415 described above, there is no description regarding a layout of the elements configuring the resistance voltage dividing circuit 100 that allows the bias current Ibias 1 and the bias current Ibias 2 to be equal.

The present disclosure provides a semiconductor device that may efficiently equalizing current flowing in one end and current flowing in the other end of a serial resistance section in which plural resistance elements are connected in series.

A first aspect of the present disclosure is a semiconductor device including: a resistance section that includes a first terminal and a second terminal disposed in contact with an outer periphery, and a serial resistance section in which plural resistance elements are connected in series, wherein one end of the serial resistance section is connected to the first terminal, and another end of the serial resistance section is connected to the second terminal; and a current adjustment section that includes a current source that supplies current to the serial resistance section, and disposed adjacent to the resistance section such that a distance between the first terminal and the current adjustment section along the outer periphery of the resistance section and a distance between the second terminal and the current adjustment section along the outer periphery of the resistance section are equal.

According to the above aspect, the present disclosure may efficiently equalize the current flowing in one end and the current flowing in the other end of the serial resistance section in which the plural resistance elements are connected in series.

Exemplary embodiments will be described in detail based on the following figures, wherein:

FIG. 1 is a circuit diagram illustrating a main configuration of a circuit provided in a semiconductor device according to a first exemplary embodiment;

FIG. 2 is a circuit diagram illustrating a main configuration of a circuit of a constant-current source according to each exemplary embodiment;

FIG. 3 is a schematic plan view that describes a layout of each configuring element of a semiconductor device according to each exemplary embodiment;

FIG. 4 is a schematic plan view that describes a modified example of the layout of each configuring element of the semiconductor device according to each exemplary embodiment;

FIG. 5 is a schematic plan view that describes an arrangement of elements configuring an operational amplifier according to each exemplary embodiment;

FIG. 6 is a circuit diagram illustrating a main configuration of a circuit provided in the semiconductor device according to the second exemplary embodiment;

FIG. 7 is a circuit diagram illustrating a main configuration of a circuit provided in the semiconductor device according to the third exemplary embodiment; and

FIG. 8 is a circuit diagram illustrating a main configuration of a conventional resistance voltage dividing circuit.

Hereinafter, exemplary embodiments of the present disclosure be described in detail with reference to the drawings.

First Exemplary Embodiment

First, a description will be given regarding a circuit configuration of a semiconductor device 10 according to a first exemplary embodiment with reference to FIG. 1 . As illustrated in FIG. 1 , the semiconductor device 10 according to the first exemplary embodiment includes a ratiometric generation circuit 12 , a ratiometric correction circuit 14 , plural (two in the first exemplary embodiment) correction target circuits 16 A and 16 B, and a correction data storing register 18 . Hereinafter, an alphabet denoted at the end of reference numeral will be omitted in a case in which it is unnecessary to distinguish the correction target circuits 16 A and 16 B.

The ratiometric generation circuit 12 includes resistance elements R 13 and R 14 , and an operational amplifier A 1 . The resistance elements R 13 and R 14 are connected in series, and a power-supply voltage VCC is supplied from one end thereof, and the other end thereof is grounded. A connection point between the resistance element R 13 and the resistance element R 14 is connected to a non-inverting input terminal of the operational amplifier A 1 . An output terminal of the operational amplifier A 1 is connected to an inverting input terminal of the operational amplifier A 1 , and is connected to the ratiometric correction circuit 14 . Namely, a voltage (here, VCC/2) divided by the resistance elements R 13 and R 14 is output from the output terminal of the operational amplifier A 1 .

The ratiometric correction circuit 14 includes a serial resistance section 20 , which includes resistance elements R 1 to R 12 connected in series, and constant-current sources I 1 and I 2 . The constant-current source I 1 is a constant-current source of a so-called discharge type which discharges a bias current Ibias 1 . The constant-current source I 1 supplies the power-supply voltage VCC from one end thereof, and the other end thereof is connected to one end of the serial resistance section 20 . Further, the constant-current source I 2 is a constant-current source of a so-called sink type which sinks a bias current Ibias 2 , and has one end being connected to the other end of the serial resistance section 20 and the other end being grounded. Further, the voltage output from the radiometric generation circuit 12 is input to a connection point f between the resistance element R 6 and the resistance element R 7 . Further, respective connection points a to k among the resistance elements R 1 to R 12 are connected respectively to correction target circuits 16 A and 16 B. Note that FIG. 1 does not illustrate a wiring between the ratiometric correction circuit 14 and the correction target circuit 16 in order to avoid the intricacy, but a to k of the ratiometric correction circuit 14 and a to k of the correction target circuit 16 are connected with one-to-one correspondence.

Namely, the voltage divided by the respective connection points a to k among the resistance elements R 1 to R 12 is output from the ratiometric correction circuit 14 . In a case in which each resistance value of the resistance elements R 1 to R 12 is set to r, for example, a voltage of VCC/2+Ibias 1 ×r×n (n=5 to 1) is output from the respective connection points a to e among the resistance element R 1 to R 6 . Further, a voltage of VCC/2 Ibias 2 ×r×n (n=1 to 5) is output from the respective connection points g to k among the resistance element R 7 to R 12 . Further, the voltage of VCC/2 is output from the connection point f between the resistance element R 6 and the resistance element R 7 .

The correction target circuit 16 includes switches S 1 to S 11 , resistance elements R 15 and R 16 , and an operational amplifier A 2 . The respective connection points a to k among the resistance elements R 1 to R 12 of the ratiometric correction circuit 14 are connected to a non-inverting input terminal of the operational amplifier A 2 , via the respective corresponding switches S 1 to S 11 . An output signal (hereinafter, referred to as a “sensor signal”) from a sensor, for example, an acceleration sensor, a gyro sensor, or the like, which is driven by the power-supply voltage VCC, is input to an inverting input terminal of the operational amplifier A 2 via the resistance element R 15 . An output terminal of the operational amplifier A 2 is connected to the inverting input terminal of the operational amplifier A 2 via the feedback resistance element R 16 .

The correction data storing register 18 includes storage area for each correction target circuit 16 individually, and outputs a digital signal according to a value stored in the storage area. Then, each ON/OFF state of the switches S 1 to S 1 is changed based on the digital signal output from the correction data storing register 18 . The switches S 1 to S 11 are set such that any one switch thereof is set to the ON state, and the other switches are set to the OFF states. Then, the voltage output from the connection points a to k connected to any one of the switches S 1 to S 11 , which has been set to the ON state, is input to the non-inverting input terminal of the operational amplifier A 2 .

Next, a description will be given regarding a circuit configuration of the constant-current sources I 1 and I 2 as examples of a current adjustment section with reference to FIG. 2 . Hereinafter, an N-channel MOS field-effect transistor will be referred to as an NMOS transistor for convenience of description. Further, a P-channel MOS field-effect transistor will be referred to as a PMOS transistor for convenience of description.

As illustrated in FIG. 2 , a current adjustment section 22 includes an operational amplifier A 3 , a resistance element R 17 , NMOS transistors N 1 to N 3 , and PMOS transistors P 1 to P 3 . A non-inverting input terminal of the operational amplifier A 3 is connected to a power source, and an output terminal of the operational amplifier A 3 is connected to a gate of the NMOS transistor N 1 . A source of the NMOS transistor N 1 is grounded via the resistance element R 17 . An inverting input terminal of the operational amplifier A 3 is connected to a connection point between the source of the NMOS transistor N 1 and the resistance element R 17 . A drain of the NMOS transistor N 1 is connected to a drain of the PMOS transistor P 1 .

The power-supply voltage VCC is supplied to each source of the PMOS transistors P 1 to P 3 . A gate of the PMOS transistor P 1 is connected to the drain of the PMOS transistor P 1 . The respective gates of the PMOS transistors P 1 to P 3 is connected to each other. A drain of the PMOS transistor P 2 is connected to a drain of the NMOS transistor N 2 . A drain of the PMOS transistor P 3 is connected to one end (an upper end illustrated in FIG. 2 ) of the serial resistance section 20 .

A gate of the NMOS transistor N 2 is connected to the drain of the NMOS transistor N 2 . The gate of the NMOS transistor N 2 is connected also to a gate of the NMOS transistor N 3 . Each source of the NMOS transistors N 2 and N 3 is grounded. A drain of the NMOS transistor N 3 is connected to the other end (a lower end illustrated in FIG. 2 ) of the serial resistance section 20 . According to the above configuration, the bias currents Ibias 1 and Ibias 2 flow in the serial resistance section 20 .

Note that the above-described sensor signal is a signal having a ratiometric characteristic, and there is a case in which a non-ratiometric component having a non-ratiometric characteristic is superimposed on this signal, due to a variation in a process of manufacturing the sensor or the like, and the signal may become offset. In such case, a predetermined process, such as a detection process, based on the sensor signal may not be properly performed. Thus, in the first exemplary embodiment, the correction is performed such that the non-ratiometric component is removed or reduced from the sensor signal containing the non-ratiometric component by the ratiometric generation circuit 12 , the ratiometric correction circuit 14 , and the correction target circuit 16 . Then, the signal after being subjected to the correction is output from the output terminal of the operational amplifier A 2 of the correction target circuit 16 . Note that the ratiometric characteristic is a characteristic that a voltage level of signal is changed in proportion to a change of power-supply voltage, and the non-ratiometric characteristic is a characteristic that the voltage level of signal is not in proportion to the change of power-supply voltage.

Next, a description will be described regarding operations of the respective circuits of the ratiometric generation circuit 12 , the ratiometric correction circuit 14 , and the correction target circuit 16 according to the first exemplary embodiment.

First, the switch S 6 is set to ON state, and the switch S 1 to 35 , S 7 to S 11 are set to OFF states so that the above-described respective circuits and sensors are driven with a voltage value of the power-supply voltage VCC being set to a first voltage value (for example, 5 V), and each output value (hereinafter, referred to as a “first output value”) of the respective correction target circuits 16 is measured. Then, the above-described respective circuits and sensors are driven with a voltage value of the power-supply voltage VCC being set to a second voltage value (for example, 5.5 V), which is higher than the first voltage value, and each output value (hereinafter, referred to as a “second output value”) of the respective correction target circuits 16 is measured.

A difference between the first output value and the second output value becomes a difference between the ratiometric components of the sensor signals, which is in proportion to a change of the voltage value of the power-supply voltage VCC. Thus, each signal level of the non-ratiometric component of the sensor signal input to the respective correction target circuits 16 is obtained from the difference between the first output value and the second output value.

Next, an input voltage (hereinafter, referred to as an “ideal input voltage”) which is necessary for removing a signal having the obtained signal level of the non-ratiometric component and is input to the non-inverting input terminal of the operational amplifier A 2 , is obtained from the obtained signal level of the non-ratiometric component. Then, any switch among the switches S 1 to S 11 to be set to ON state is determined, such that a voltage closest to the obtained ideal input voltage is input to the non-inverting input terminal of the operational amplifier A 2 . Further, a value to set the determined switch to ON state is stored in the storage area corresponding to each of the correction target circuits 16 of the correction data storing register 18 .

In this manner, the above-described respective circuits and sensors are driven in a state in which one among the switches S 1 to S 11 is set to ON state based on the stored value of the correction data storing register 18 . Accordingly, the sensor signal in which the non-ratiometric component is corrected is output from the respective correction target circuits 16 .

As described above, in the semiconductor device 10 of the first exemplary embodiment, the sensor signal to be input to the plural correction target circuits 16 can be corrected by single ratiometric correction circuit 14 . Not that the number of the correction target circuits 16 is not limited to two, but may be three or more.

As described above, differences in voltages output from the respective connection points a to k approximate uniformity as a difference between the bias current Ibias 1 and the bias current Ibias 2 becomes small. Further, it is possible to input a voltage close to the ideal input voltage to the non-inverting input terminal of the operational amplifier A 2 as the differences in voltages output from the respective connection points a to k becomes close to the uniformity. Namely, it is possible to accurately correct the non-ratiometric component of the sensor signal as the difference between the bias current Ibias 1 and the bias current Ibias 2 becomes small. Thus, in the semiconductor device 10 according to the first exemplary embodiment, the layout of the respective elements configuring the semiconductor device 10 is defined in order to equalize the bias current Ibias 1 and the bias current Ibias 2 .

Next, a description will be given regarding a layout of the semiconductor device 10 according to the first exemplary embodiment with reference to FIG. 3 .

As illustrated in FIG. 3 , the semiconductor device 10 according to the first exemplary embodiment has an area being divided into a serial resistance block 30 in which the serial resistance section in which the plural resistance elements are connected in series is disposed, and amplifier blocks 32 A to 32 N in which configuring sections including an operational amplifier are disposed.

The serial resistance section 20 is disposed in the serial resistance block 30 , one end of the serial resistance section 20 is connected to a first terminal 34 A, and the other end of the serial resistance section 20 is connected to a second terminal 34 B. The first terminal 34 A and the second terminal 349 are disposed in contact with an outer periphery of the serial resistance block 30 at an inner side of the serial resistance block 30 .

The current adjustment section 22 is disposed, for example, in the amplifier block 32 H (part with the oblique lines illustrated in FIG. 3 ), which is adjacent to the serial resistance block 30 . Namely, as illustrated in FIG. 3 , the current adjustment section 22 is disposed at a position at which a distance K1 along the outer periphery of the serial resistance block 30 from the first terminal 34 A and a distance K2 along the outer periphery of the serial resistance block 30 from the second terminal 34 B are equal. Note that the term of “equal” used here means not only completely “equal”, but also a concept which includes an error that the difference between the bias current Ibias 1 and the bias current Ibias 2 is within a tolerance range. Due to the above, since a wiring length between the current adjustment section 22 and the first terminal 34 A, and a wiring length between the current adjustment section 22 and the second terminal 349 are efficiently equalized, the bias current Ibias 1 and the bias current Ibias 2 may be efficiently equalized.

Note that the layout of the first terminal 34 A, the second terminal 34 B and the current adjustment section 22 is not limited to the example illustrated in FIG. 3 . For example, as illustrated in FIG. 4 , the first terminal 34 A may be disposed in contact with a side (left side in FIG. 4 ) of the outer periphery of the serial resistance block 30 , and the second terminal 34 B may be disposed in contact with a side (lower side in FIG. 4 ) that contacts with the above-described side of the serial resistance block 30 . In such case, the current adjustment section 22 may be disposed in the amplifier block 32 L. Namely, another layout may be possible as long as the distance K1 along the outer periphery of the serial resistance block 30 between the first terminal 34 A and the current adjustment section 22 and the distance K2 along the outer periphery of the serial resistance block 30 between the second terminal 349 and the current adjustment section 22 are equal.

Further, the ratiometric generation circuit 12 is disposed in the amplifier block 32 J, the correction target circuits 16 A and 16 B are disposed respectively in the amplifier blocks 32 D and 32 F, for example, in the first exemplary embodiment.

Meanwhile, in the case of correcting the non-ratiometric component of the sensor signal, there may be a case in which the signal is offset by the non-ratiometric component superimposed on a signal flowing to each circuit, due to the variation in a process of manufacturing the respective operational amplifiers A 1 to A 3 .

Accordingly, in the semiconductor device 10 according to the first exemplary embodiment, the respective operational amplifiers A 1 to A 3 have the same configuring elements, and are disposed in the same direction with respect to the corresponding amplifier blocks, in order to reduce a difference of the offset caused by the variation in each of the operational amplifiers A 1 to A 3 . To be more specific, each arrangement and each connection of the elements configuring the operational amplifiers A 1 to A 3 are formed to be the same. Note that the term of the “same” used here means not only completely the same, but also a concept which includes an error caused in a manufacturing process or the like.

A description will be given regarding the arrangement of elements configuring the operational amplifiers A 1 to A 3 with reference to FIG. 5 . As illustrated in FIG. 5 , for example, in a case in which the operational amplifiers A 1 to A 3 have transistors Tr 1 to Tr 3 as elements configuring the operational amplifiers A 1 to A 3 , the corresponding transistors Tr 1 to Tr 3 of the operational amplifiers A 1 to A 3 are disposed at the same positions in the operational amplifiers A 1 to A 3 . Further, the corresponding transistors Tr 1 to Tr 3 of the operational amplifiers A 1 to A 3 are disposed in the same direction in the same connection state in the first exemplary embodiment.

The term “same direction”, used here, means that terminals T 1 to T 3 of the corresponding transistors Tr 1 to Tr 3 of the operational amplifiers A 1 to A 3 are disposed at the same positions, respectively, in the operational amplifiers A 1 to A 3 , for example. In this manner, the operational amplifiers A 1 to A 3 are disposed in the same directions in the respective amplifier blocks in which the respective operational amplifiers A 1 to A 3 are disposed, and thus, it is possible to reduce the difference of the offset caused by the variation in each of the operational amplifiers A 1 to A 3 . Note that the arrangement positions of the operational amplifiers A 1 to A 3 in the respective amplifier blocks may be the same or may be different from each other.

Second Exemplary Embodiment

First, a description will be given regarding a circuit configuration of the semiconductor device 10 according to a second exemplary embodiment with reference to FIG. 6 . Note that, in FIG. 6 , elements that have the same functions as those in FIG. 1 will be attached with the same reference numerals, and the description thereof will be omitted.

As illustrated in FIG. 6 , the ratiometric correction circuit 14 according to the second exemplary embodiment includes constant-current sources I 1 A to I 1 D and I 2 A to I 2 D, switches S 12 to S 19 , and a correction width changing register 40 . The constant-current source I 1 A to I 1 D are discharge type constant-current sources similarly to the constant-current source I 1 of the first exemplary embodiment. Further, each of the constant-current sources I 1 A to I 1 D has one end to which the power-supply voltage VCC is supplied, and the other end being connected to one end of the serial resistance section 20 via each of the switches S 12 to S 15 . Further, the respective constant-current sources I 1 A to I 1 D are set to cause currents having different magnitudes to flow in the second exemplary embodiment.

The constant-current source I 2 A to I 2 D are sink type constant-current sources similarly to the constant-current source I 2 of the first exemplary embodiment. Further, each of the constant-current source I 2 A to I 2 D has one end being connected to the other end of the serial resistance section 20 via each of the corresponding switches S 16 to S 19 , and the other end being grounded. Further, the constant-current source I 2 A to I 2 D have one-to-one correspondence with the constant-current sources I 1 A to respectively, and are set to cause current, which has the same magnitude with the corresponding constant-current sources I 1 A to I 1 D to flow. Further, each of the switches S 12 to S 15 and each of the switches S 16 to S 19 has one-to-one correspondence, and each ON/OFF state of the corresponding switches (for example, the switch S 12 and the switch S 16 ) is the same.

The correction width changing register 40 is provided with a storage area, and each ON/OFF state of the switches S 12 to S 15 and the corresponding switches S 16 to S 19 is changed based on a digital signal to be output according to a value stored in the storage area

Next, a description regarding operations of the respective circuits of the ratiometric generation circuit 12 , the ratiometric correction circuit 14 , and the correction target circuit 16 according to the second exemplary embodiment will be described.

First, the switches S 12 and S 16 are set to ON states, the switches S 13 to S 15 and S 17 to S 19 are set to OFF states, and a first output value and a second output value are measured in the same manner as in the first exemplary embodiment.

Next, an ideal input voltage is obtained based on a difference between the first output value and the second output value similarly to the first exemplary embodiment. Then, a pair of a switch among the switches S 1 to S 11 and a switch among the switches S 12 to S 19 to be set to ON state is determined, such that a voltage closest to the obtained ideal input voltage is input to the non-inverting input terminal of the operational amplifier A 2 . Further, each value to set the determined switches to ON states is stored in the storage area corresponding to each of the correction target circuits 16 of the correction data storing register 18 , and the storage area of the correction width changing register 40 .

In this manner, the above-described respective circuits and sensors are driven in a state in which the pair of any switch among the switches S 1 to S 11 and any switch among the switches S 12 to S 19 is set to ON state based on the stored values of the correction data storing register 18 and the correction width changing register 40 . Accordingly, the sensor signal in which the non-ratiometric component is corrected is output from the respective correction target circuits 16 .

As described above, in the semiconductor device 10 according to the second exemplary embodiment, each potential difference among the connection points a to k may be set minutely with more steps numbers, as compared to the first exemplary embodiment. As a result, the semiconductor device 10 according to the second exemplary embodiment may select a voltage far closer to the ideal input voltage, and may more accurately correct the sensor signal.

Note that, there may be a case in which each ideal input voltage obtained for each of the plural correction target circuits 16 are greatly different, and a combination of the switches S 12 to S 19 to be set to ON state in correspondence with the voltage closest to each ideal input voltage becomes different. In such case, for example, it is considered that a combination of the switches S 12 to S 19 , which corresponds to a large ideal input voltage, is set to ON state. In such case, there may be cases in which the sensor signal is not accurately corrected in the correction target circuit 16 with a small ideal input voltage.

With respect to this, in the present disclosure as described above, the elements configuring the operational amplifiers A 1 to A 3 have the same arrangement, and thus, the difference of the offset caused by the variation of the operational amplifiers A 1 to A 3 is reduced as compared to a case in which the elements configuring the operational amplifiers A 1 to A 3 are disposed in different states. Therefore, the semiconductor device 10 according to the second exemplary embodiment may accurately correct the sensor signal to be input to the respective correction target circuits 16 as a result of reducing the difference in the ideal input voltages of the respective correction target circuits 16 as compared to a case in which the elements configuring the operational amplifiers A 1 to A 3 are disposed in different states.

Third Exemplary Embodiment

First, a description will be given regarding a circuit configuration of the semiconductor device 10 according to a third exemplary embodiment with reference to FIG. 7 . Note that, in FIG. 7 , elements that have the same functions as those in FIG. 6 will be attached with the same reference numerals, and the description thereof will be omitted.

As illustrated in FIG. 7 , the correction target circuit 16 A according to the third exemplary embodiment includes resistance elements R 18 to R 20 , switches S 20 to S 23 , again changing register 42 , and a decoder 44 . The resistance elements R 16 and R 18 to R 20 are connected in series. The switches S 20 to S 23 are provided in correspondence with the respective resistance elements R 16 and R 18 to R 20 , and are connected in series. Both ends of each of the switches S 20 to S 23 connected in series, are connected to both ends of each of the resistance elements R 16 and R 18 to R 20 connected in series. Each connection point among the switches S 20 to S 23 is connected to each connection point among the corresponding resistance elements R 16 and R 18 to R 20 . Namely, an amplification rate (gain) of the operational amplifier A 2 is changed depending on each ON/OFF state of the switches S 20 to S 23 .

The gain changing register 42 is provided with a storage area, and each ON/OFF state of the switches S 12 to S 15 and the corresponding switches S 16 to S 19 is changed based on digital signals g 1 to g 4 to be output according to a value stored in the storage area. Further, the digital signals g 1 to g 4 are input to the decoder 44 , and each ON/OFF state of the switches S 20 to S 23 is changed by the signal decoded by the decoder 44 .

The third exemplary embodiment is configured such that each magnitude of the bias current Ibias 1 and the bias current Ibias 2 is changed depending on the amplification rate of the operational amplifier A 2 . As an example, a description will be given regarding a case in which each resistance value of the resistance elements R 15 and R 16 is set to r, a resistance value of resistance element R 18 is set to 2×r, a resistance value of the resistance element R 19 is set to 4×r, and a resistance value of the resistance element R 20 is set to 8×r. Further, as the example, the description will be given regarding a case in which a current amount discharged by the constant-current source I 1 A and a current amount sunk by the constant-current source I 2 A are set to Iref, and a current amount discharged by the constant-current source I 1 B and a current amount sunk by the constant-current source I 2 B are set to 2×Iref. Furthermore, as the example, the description will be given regarding a case in which a current amount discharged by the constant-current source I 1 C and a current amount sunk by constant-current source I 2 C are set to 4×Iref, and a current amount discharged by the constant-current source I 1 B and a current amount sunk by the constant-current source I 2 D are set to 8×Iref.

For example, the switches S 20 to S 22 are set to ON states, and the switch S 23 is set to OFF state in a case in which the amplification rate of the operational amplifier A 2 is set to 8 times. Further, the switches S 12 to S 14 and S 16 to S 18 are set to OFF states, and the switches S 15 and S 19 are set to ON states in this case.

Operations of respective circuits including the ratiometric generation circuit 12 , the ratiometric correction circuit 14 , and the correction target circuit 16 according to the third exemplary embodiment other than the above-described point are the same as those in the first exemplary embodiment and the second exemplary embodiment, and thus, the description thereof will be omitted.

In a case in which the amplification rate of the operational amplifier A 2 is set to a value that exceeds 1 time, namely, an offset voltage input to the non-inverting input terminal of the operational amplifier A 2 ×an error of the amplification rate is output from the output terminal of the operational amplifier A 2 . Accordingly, in such case, the correction of the sensor signal may not be accurately performed. On the contrary, each magnitude of the bias current Ibias 1 and the bias current Ibias 2 is changed in proportion to the amplification rate of the operational amplifier A 2 in the third exemplary embodiment. Accordingly, each potential difference among the respective connection points a to k is changed in proportion to the amplification rate of the operational amplifier A 2 . Accordingly, the present exemplary embodiment may accurately correct the sensor signal.

Although FIG. 7 illustrates a case in which the single correction target circuit 16 is provided, the plural correction target circuits 16 may be provided as long as the amplification rate of the operational amplifier A 2 is the same value. Further, the correction target circuit 16 of the first exemplary embodiment and the second exemplary embodiment may be provided further to the correction target circuit 16 of the third exemplary embodiment.