JP3548974B2 - Magnetic detection circuit - Google Patents

Description

ここで、本発明に用いたプロセスの場合、
１／Ｒ３・ｄＲ３／ｄＴ≒２０００ｐｐｍ／℃ であり、
１／ＶＦ・ｄＶＦ／ｄＴ≒−２０００ｐｐｍ／℃ であるので、
１／ＶＦ・ｄＶＦ／ｄＴ＝−１／Ｒ３・ｄＲ３／ｄＴ とおいて、（１０）式は、
ｄＩ３／ｄＴ＝１／Ｒ３・ｄＲ３／ｄＴ・（１／Ｒ３）・｛−Ｉ２Ｒ２−ＶＢ＋２ＶＦ｝ ・・・（１１）
式（１１）から、電流Ｉ３の温度特性を０ｐｐｍ／℃とするには、
２ＶＦ−ＶＢ−Ｉ２・Ｒ２＝０
とすれば良い。具体的には、Ｉ２≒２００μＡ、Ｒ２＝１．５ｋΩ、ＶＢ＝１．４５Ｖ、ＶＦ≒０．８Ｖとすることで、電流Ｉ３の温度特性としてほぼ０ｐｐｍ／℃が達成される。そして、このような電流が、カレントミラー回路を介してホール素子の定電流源５やコンパレータ７以外のアンプの定電流トランジスタＱ３２に転写され、温度依存性のない電流がそれぞれのアンプに流されて駆動されることとなる。
【００３６】
一方、上記電流源１４は、電流源１２内のトランジスタＱ６とカレントミラー接続されたトランジスタＱ８と直列形態に接続されて温度依存性のない電流が流されるトランジスタＱ２１と、このＱ２１とベースが結合されてカレントミラー回路を構成するトランジスタＱ２２と、上記メイン電流源１３内の−２０００ｐｐｍ／℃の温度特性を有する電流が流されるトランジスタＱ１とカレントミラー接続されたトランジスタＱ２３と、このトランジスタＱ２３と上記トランジスタＱ２２のコレクタに共通にコレクタが接続され、Ｑ２２とＱ２３に流れる電流Ｉ３とＩ１を合成した電流Ｉ４を流すトランジスタＱ２４とによって構成されている。
【００３７】
これによってトランジスタＱ２４には、０ｐｐｍ／℃と−２０００ｐｐｍ／℃の平均である−１０００ｐｐｍ／℃の温度特性を有する電流Ｉ４が流されることとなる。そして、上記トランジスタＱ２４とホール素子２および３の定電流源５を構成するトランジスタＱ３０とがカレントミラー接続され、トランジスタＱ２４に流れる電流と同一の温度特性の電流がホール素子に流され、ホール素子の磁気−電気変換特性の有する１０００〜３０００ｐｐｍ／℃の正の温度依存性が−１０００ｐｐｍ／℃の負の温度特性を持つ電流で補償され、ホール素子２および３の磁気−電気変換特性は−５００ｐｐｍ／℃以下の温度依存性を呈するようにされる。
【００３８】
以上説明したように、上記実施例は、ホール素子の駆動回路として定電圧源の代わりに定電流源を用いることによりホール素子の磁気−電気変換特性の温度依存性を定電流源の負の温度特性で補償するとともに、ホール素子の出力を弁別するコンパレータのスレッシュホールドレベルを発生する抵抗の温度依存性をその抵抗に流れる電流を与える定電流源の負の温度特性で補償させるようにしたので、高温度領域においても高い電圧を必要としなくても済むようになるとともに、上記のように負の温度特性を有する定電流源はシリコンチップ上において簡単に実現できるため、広い温度範囲で動作可能なモノリシックＩＣセンサを低コストで提供することができるようになるという効果がある。
【００３９】
以上本発明者によってなされた発明を実施例に基づき具体的に説明したが、本発明は上記実施例に限定されるものではなく、その要旨を逸脱しない範囲で種々変更可能であることはいうまでもない。例えば上記実施例では、ダミーホール素子３を設けてその出力平均値をとってコンパレータ７への動作点を与えるようにしているが、コンパレータの動作点はそれに限定されず、任意の安定なレベルを用いるようにすることができる。また、実施例では、ホール素子の出力からＤＣレベルを除去するためピークホールド回路８とコンダクタンスアンプ９とを設けているが、これらの回路を省略することも可能である。
【００４０】
以上の説明では主として本発明者によってなされた発明をその背景となった利用分野であるホール素子を用いた磁気センサに適用した場合について説明したがこの発明はそれに限定されるものでなく、半導体集積回路における温度補償回路一般に利用することができる。
【００４１】
【発明の効果】
本願において開示される発明のうち代表的なものによって得られる効果を簡単に説明すれば下記のとおりである。
【００４２】
すなわち、ホール素子の磁気−電気変換特性の温度依存性を補償するとともに、ホール素子とその周辺回路を一つのシリコンチップ上に有し低電圧で駆動可能なモノリシックＩＣセンサを低コストで製造することができ、これによって広い温度範囲において動作可能な自動車のトランスミッションやエンジン等の回転検出に好適なセンサを提供できるようになる。
【図面の簡単な説明】
【図１】モノリシックＩＣ化された本発明に係る磁気センサの一実施例を示すブロック構成図。
【図２】実施例の磁気センサＩＣのチップ上におけるホール素子の構造の一例を示す断面図。
【図３】実施例の磁気センサ内のコンパレータの具体例を示す回路図。
【図４】実施例の磁気センサ内の電流源の具体例を示す回路図。
【符号の説明】
１ シリコンチップ
２ ホール素子
３ ダミーホール素子
４ 定電圧電源回路
５ 定電流源
７ コンパレータ
６，９ アンプ
１０ 出力トランジスタ
１１ バンドギャップ基準電圧発生回路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technology that is effective when applied to temperature compensation of a magnetic sensor drive circuit and a signal detection circuit using a Hall element, for example, a monolithic IC in which a Hall element and its peripheral circuit are formed on one silicon chip. It relates to technology effective for use in sensors.
[0002]
[Prior art]
Conventionally, Hall elements having magnetic-electric conversion characteristics have been used as sensors in various measuring instruments and control systems. It is known that the magnetic-electric conversion characteristics of a Hall element have a temperature dependence, and a magnetic sensor using a Hall element is sometimes used in an environment where a temperature change is relatively large. Various types of temperature compensating circuits have been proposed in the past to obtain a stable output, such as Japanese Patent Publication No. 3-51118 and Japanese Patent Application Laid-Open No. 57-197883.
[0003]
The invention disclosed in Japanese Patent Publication No. 3-51118 focuses on the fact that the temperature dependence of the magneto-electric conversion characteristics of the Hall element substantially coincides with the temperature dependence of the drive current, and a monitoring means for detecting the drive current of the Hall element. A circuit for generating a voltage proportional to the detected current is provided, and temperature compensation is performed by applying a stable threshold voltage to a comparator for discriminating the output of the Hall element.
[0004]
The invention of Japanese Patent Application Laid-Open No. 57-197883 is designed to compensate for the temperature dependence of the magneto-electric conversion characteristics of the Hall element by driving the Hall element with a constant voltage source having an appropriate temperature and temperature dependence. It was made.
[0005]
[Problems to be solved by the invention]
In the method of monitoring the drive current of the Hall element in the above-mentioned prior invention, since a current proportional to the detected drive current is caused to flow through a resistor to generate a threshold level, there is no temperature dependency. It requires negligible or negligible resistance. However, realizing such a resistor in a monolithic IC is very difficult with current semiconductor integrated circuit technology, and has the disadvantage of increasing the cost.
[0006]
On the other hand, in the method in which the Hall element is driven by a constant voltage source having an appropriate temperature dependency, in order to minimize the magneto-electric conversion characteristics of the Hall element, the Hall element has a positive temperature dependency as a constant voltage source. However, it has been found that forming such a constant voltage source on a silicon chip has a problem that the required voltage in a high temperature region becomes extremely high.
[0007]
An object of the present invention is to provide a circuit technology capable of compensating for the temperature dependence of the magneto-electric conversion characteristics of a Hall element.
[0008]
Another object of the present invention is to provide a low-cost monolithic IC sensor which has a Hall element and its peripheral circuits on one silicon chip and can be driven at a low voltage.
[0009]
It is another object of the present invention to provide a sensor suitable for detecting rotation of a transmission or an engine of an automobile, which can operate in a wide temperature range and includes a peripheral circuit and can be easily made into a monolithic IC. .
[0010]
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0011]
[Means for Solving the Problems]
The outline of a representative invention among the inventions disclosed in the present application will be described as follows.
[0012]
That is, by using a constant current source instead of a constant voltage source as a drive circuit of the Hall element, the temperature dependence of the magneto-electric conversion characteristics of the Hall element is compensated for by the negative temperature characteristic of the constant current source, and the Hall element is driven. The temperature dependency of a resistor that generates a threshold level of a comparator for discriminating an output is compensated for by the negative temperature characteristic of a constant current source that supplies a current flowing through the resistor.
[0013]
When a Hall element is formed on a silicon chip, an n-type semiconductor layer composed of an epitaxial layer or a diffusion layer is used. In this case, the magneto-electric conversion characteristics of the Hall element depend on the carrier concentration. Has an impurity concentration of about 1 × 10 16 / cm 3 or less. When the Hall element formed with such specifications is driven at a constant voltage, the temperature dependence of the current consumption becomes about -4000 to -7000 ppm / ° C., and the magnetic-electric conversion characteristics show the same temperature dependence. However, when the above-described Hall element is driven with a constant current, it has a positive temperature coefficient and the magnetic-electric conversion characteristic has a temperature dependence of about 1000 to 3000 ppm / ° C. Therefore, by driving the Hall element with a constant current source having a negative temperature characteristic of about -500 to -2000 ppm / ° C., the magneto-electric conversion characteristic of the Hall element can be minimized.
[0014]
As described above, since the Hall element can be driven by the constant current source instead of the constant voltage source, it is not necessary to require a high voltage even in a high temperature region, and the negative temperature is reduced as described above. Since a constant current source having characteristics can be easily realized on a silicon chip, a monolithic IC sensor operable in a wide temperature range can be provided at low cost.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 shows a magnetic sensor according to the present invention in the form of a monolithic IC. 1 is a single-crystal silicon chip, 2 is a Hall element formed as an n-type epitaxial layer on this silicon chip, and 3 is an operating point of an internal circuit. Therefore, it is a dummy Hall element composed of an n-type epitaxial layer like the Hall element. A constant voltage from a constant voltage power supply circuit 4 is applied to one power supply terminal of these Hall elements 2 and 3, and a constant current source 5 is connected between the other power supply terminal and a ground point. The constant current source 5 drives the Hall elements 2 and 3.
[0017]
A pair of output terminals of the Hall element 2 are connected to a differential input terminal of an amplifier 6 at the next stage, and an output voltage of the amplifier 6 is input to an inverting input terminal of a comparator 7 and the dummy Hall element Reference numeral 3 denotes a short-circuited connection between a pair of output terminals, the voltage of which is applied to a non-inverting input terminal of a comparator 7 as a reference voltage Vr that provides an operating point.
[0018]
Although not particularly limited, a peak hold circuit 8 composed of a low-pass filter having a large time constant for detecting the peak level of the output voltage of the amplifier 6, ie, the DC level, is connected to the input terminal side of the comparator 7. The voltage detected by the hold circuit 8 is fed back to the inverting input terminal of the amplifier 6 via the conductance amplifier 9. As a result, the DC component of the signal transmitted from the Hall element 2 to the comparator 7 is removed, and only the time-varying AC component (ripple) of the detection signal of the Hall element 2 is input to the comparator 7 and the reference voltage The output of the output bipolar transistor 10 is compared with the output voltage Vr, and the output of the output bipolar transistor 10 is driven to output the output bipolar transistor 10 to the outside in the form of an output current.
[0019]
The magnetic sensor of this embodiment includes a bandgap reference voltage generating circuit 11 for generating a constant voltage corresponding to the bandgap of silicon irrespective of temperature fluctuations, and three magnetic sensors each designed to have predetermined temperature characteristics. Current sources 12, 13, and 14 are provided. The current source 14 among the three current sources 12 to 14 generates a current having a temperature characteristic of about −1000 ppm / ° C. based on the constant voltage from the bandgap reference voltage generation circuit 11 and supplies the current to the constant current source 5. And the Hall elements 2 and 3 are driven by the applied current.
[0020]
When the Hall element is driven at a constant current, it has a positive temperature coefficient and the magnetic-electric conversion characteristic has a temperature dependence of about 1000 to 3000 ppm / ° C., but a current source having a negative temperature characteristic of −1000 ppm / ° C. By driving the Hall elements 2 and 3, the magneto-electric conversion characteristics of the Hall elements 2 and 3 exhibit a temperature dependency of −500 ppm / ° C. or less.
[0021]
On the other hand, the current source 13 among the three current sources 12 to 14 forms a current having a temperature characteristic of about −2000 ppm / ° C. based on the constant voltage from the bandgap reference voltage generation circuit 11 and supplies the current to the comparator 7. By supplying the current and flowing the current through a resistor that determines a threshold voltage inside the comparator, a positive temperature coefficient of about 2000 ppm / ° C. of the resistor can be canceled, and a stable threshold voltage can be formed regardless of temperature fluctuation. It is configured as follows.
[0022]
Further, the current source 12 among the three current sources 12 to 14 generates a temperature characteristic of 0 ppm / ° C., that is, a current having no temperature dependence, based on the constant voltage from the bandgap reference voltage circuit 11 to generate the constant current. The amplifier is supplied to amplifiers other than the source 5 and the comparator 7 (6 and 9 in the embodiment of FIG. 1), and each amplifier is driven by the temperature-independent current. Since these amplifiers are configured as circuits whose gains are determined by the ratios of the resistances, the gains do not fluctuate .
[0023]
Next, a more specific embodiment of the magnetic sensor IC of the above embodiment will be described. FIG. 2 shows an example of a cross-sectional structure of the Hall element 2 on a chip. In the Hall element of this embodiment, a P-type isolation region 22 is formed around an n-type epitaxial layer 21 formed on a p-type silicon single crystal substrate 1 so as to reach the substrate surface. On the surface of 21, a p-type diffusion layer 23 is formed. The n + -type regions 24a and 24b on the substrate surface are contact regions for power terminals provided at both ends of the n-type epitaxial layer 21, and 25a and 25b are output terminals provided on both sides of the center of the n-type epitaxial layer 21. It is a contact area.
[0024]
In the Hall element composed of the epitaxial layer 21 formed on the silicon chip, a current corresponding to the magnitude of the detected magnetism flows along the surface, so that the chip surface is contaminated or defective during the process. Then, the current changes, but in this embodiment, since the surface of the n-type epitaxial layer 21 is covered with the p-type diffusion layer 23 having the same potential as the substrate 1, the current flowing through the epitaxial layer as the Hall element is Since the current flows between the p-type diffusion layer 23 and the substrate 1 and the current is not affected by contamination or defects on the substrate surface, a stable detection output with little variation can be obtained.
[0025]
FIG. 3 shows a specific circuit example of the comparator 7. The comparator 5 of this embodiment includes a pair of differential transistors Q11 and Q12, a constant current transistor Q13 connected to the emitter terminal of Q11, and a collector between the differential transistors Q11 and Q12 and a power supply voltage terminal Vcc. Load resistors R11 and R12 connected, a threshold generation resistor R13 connected between the emitter of the transistor Q12 and the collector of the constant current transistor transistor Q13, and a transistor having a base connected to the collector of the transistor Q12. Q14, a transistor Q15 connected to the emitter of the transistor Q14 to form a current switch circuit, a transistor Q16 for a constant current connected to the common emitter, and a base connected to the transistor Q15 to form a current mirror circuit Do And a transistor Q17 Metropolitan.
[0026]
In the comparator of this embodiment, while the potential difference (Vin2-Vin1) between the voltages Vin1 and Vin2 input to the input terminals is smaller than the potential difference between both ends of the resistor R13, a current flows to the transistor Q11 side and the collector voltage of the Q12 is increased. Is set to a level close to Vcc, the transistor Q14 is turned off, a current flows to the side of Q15, and the current transferred to Q17 by the current mirror flows as an output current. When the potential difference (Vin2−Vin1) of the input voltage becomes larger than the potential difference between both ends of the resistor R13, the current flowing to the transistor Q11 flows to Q12, the collector voltage of the current drops, and the transistor Q14 is turned on. The current flowing to the side flows to Q14, and the output current is cut off.
[0027]
In the comparator of this embodiment, although the threshold generation resistor R3 has a temperature characteristic of about 2000 ppm / ° C., the constant current transistor Q13 has a constant current of −2000 ppm / ° C. in the current source 13. A constant current having a temperature characteristic of −2000 ppm / ° C. flows through the threshold generation resistor R13 by being connected to an output transistor (to be described later) through which current flows. As a result, the positive temperature coefficient of about 2000 ppm / ° C. of the resistor R13 is canceled, and a stable threshold voltage is formed regardless of the temperature fluctuation.
[0028]
FIG. 4 shows a specific circuit example of the current sources 12 to 14. In the circuit of this embodiment, the current source 13 is used as a main current source, and the current sources 12 and 14 are configured as sub-current sources that generate respective currents based on the current generated by the main current source 13. ing.
[0029]
A main current source 13 has a base coupled to each other and an emitter connected to a power supply voltage terminal Vcc, and a pair of pnp transistors Q1 and Q2 constituting a first current mirror circuit. It has a pair of npn transistors Q3 and Q4 connected to the collectors of the current mirror transistors Q1 and Q2 to form a second current mirror circuit. A resistor R1 is connected between the emitter of the transistor Q3 and a ground point. The resistor R2 is connected between the collector of the transistor Q4 and the collector of Q2, and the constant voltage VB from the bandgap reference voltage generation circuit 11 is applied to the emitter of Q4.
[0030]
As a result, the same current flows to the resistor R1 and the reference voltage generation circuit 11 by the transistors Q3 and Q4, and the same voltage VB is applied to the resistor R1. Therefore, assuming that the resistance value of the resistor R1 is R1 and the current flowing through the resistor R1 is I1 , the temperature dependency of the current I1 flowing through the resistor R1 is as follows.
dI1 / dT = d (VB / R1) / dT
Where VB can be considered to be substantially constant regardless of temperature fluctuations.
dI1 / dT ≒-(VB / R1) D (1 / R1) D (dR1 / dT)
It becomes.
[0031]
In this embodiment, since the resistor R1 is formed of a resistor having the same positive temperature coefficient of about 2000 ppm / ° C. as the resistor R13 in the comparator 7, the temperature dependency of the current flowing through the resistor R1 is −2000 ppm / ° C. The current of -2000 ppm / ° C. flows to the transistor Q 1, and further flows to the constant current transistor Q 13 in the comparator 7 via the current mirror circuit 31. As a result, in the comparator 7, the 2000 ppm / ° C. temperature characteristic of the threshold generation resistor R13 is canceled by the constant current having a temperature characteristic of −2000 ppm / ° C. flowing through the constant current transistor Q13. Regardless, a stable threshold voltage is formed.
[0032]
Next, the current source 12 includes a transistor Q5 having a base connected to a connection node n1 between the collector of the transistor Q2 and the resistor R2 and a collector connected to the power supply voltage terminal Vcc, an emitter terminal of the transistor Q5 and a ground point. And a resistor R3 and a diode-connected transistor Q6 connected in series. The constant current source 5 of the Hall element and the constant current transistors in the amplifiers (6 and 9 in the embodiment of FIG. 1) other than the comparator 7 are current mirror-connected to the transistor Q6. The same current as the current I3 flowing through the transistor Q6 flows through amplifiers other than the source 5 and the comparator 7.
[0033]
In the current source 12 of this embodiment, the current flowing through the resistor R3 is I3, the resistance value of the resistor R2 is R2, the current flowing through the resistor R2 is I2, and the forward voltage between the base and the emitter of the transistors Q4, Q5, and Q6 is VF. Then, the base potential V1 of Q5 is changed from the current path of R2 to Q4.
V1 = I2 · R2 + VF + VB ‥‥‥ (1)
From the current path of Q5-R3-Q6, V1 = VF + I3 · R3 + VF ＋ (2)
From equations (1) and (2), I2２R2 + VF + VB = VF + I3 ・ R3 + VFＶ (3)
I3 · R3 = I2 · R2 + VB−VF ‥‥‥‥‥‥ (4)
∴I3 = (R2 / R3) I2 + VB / R3-VF / R3
It becomes. Therefore, the temperature dependency dI3 / dT of the current I3 is
dI3 / dT = d / dT (R2 / R3) .I2 + (R2 / R3) dI2 / dT + d / dT (VB / R3) -d / dT (VF / R3) (6)
It becomes.
[0034]
Here, if R2 and R3 are the same type of resistor,
d / dT (R2 / R3) = 0
Since the temperature dependency of VB is sufficiently small that dVB / dT ≒ 0, the equation (6) is
dI3 / dT = (R2 / R3) dI2 / dT + VBd / dT (1 / R3) -dVF / dT (1 / R3) -VFd / dT (1 / R3) (7)
It becomes.
[0035]
Here, from the relationship of I2 = I1 = VB / R1,
R1 · dI2 / dT + I2 · dR1 / dT = dVB / dT = 0
Multiply both sides by (1 / R1) I2,
1 / I2 · dI2 / dT = -1 / R1 · dR1 / dT (8)
On the other hand, since R1, R2, and R3 are the same type of resistance,
1 / I2 · dI2 / dT = −1 / R1 · dR1 / dT = −1 / R2 · dR2 / dT = −1 / R3 · dR3 / dT (9)
Formula (7) is rearranged using formula (9).

Here, in the case of the process used in the present invention,
1 / R3 · dR3 / dT ≒ 2000 ppm / ° C.
1 / VF · dVF / dT ≒ −2000 ppm / ° C.
1 / VF · dVF / dT = −1 / R3 · dR3 / dT Equation (10)
dI3 / dT = 1 / R3 · dR3 / dT · (1 / R3) · {−I2R2-VB + 2VF} (11)
From the equation (11), to set the temperature characteristic of the current I3 to 0 ppm / ° C.,
2VF-VB-I2.R2 = 0
It is good. Specifically, by setting I2 ≒ 200 μA, R2 = 1.5 kΩ, VB = 1.45 V, and VF ≒ 0.8 V, almost 0 ppm / ° C. is achieved as the temperature characteristic of the current I3. Then, such a current is transferred to the constant current source 5 of the Hall element and the constant current transistor Q32 of the amplifier other than the comparator 7 via the current mirror circuit, and a current having no temperature dependency flows to each amplifier. It will be driven.
[0036]
On the other hand, the current source 14 is connected in series with a transistor Q8, which is current-mirror-connected to the transistor Q6 in the current source 12, and a transistor Q21 through which a current having no temperature dependency flows is connected to the transistor Q21. A transistor Q22 which forms a current mirror circuit, a transistor Q23 in the main current source 13 through which a current having a temperature characteristic of -2000 ppm / ° C. flows, and a transistor Q23 which is current-mirror-connected, the transistor Q23 and the transistor Q22 And a transistor Q24 that flows a current I4 obtained by combining currents I3 and I1 flowing through Q22 and Q23.
[0037]
As a result, a current I4 having a temperature characteristic of −1000 ppm / ° C., which is an average of 0 ppm / ° C. and −2000 ppm / ° C., flows through the transistor Q24. Then, the transistor Q24 and the transistor Q30 constituting the constant current source 5 of the Hall elements 2 and 3 are current-mirror connected, and a current having the same temperature characteristic as the current flowing through the transistor Q24 flows through the Hall element. The positive temperature dependency of 1000 to 3000 ppm / ° C of the magneto-electric conversion characteristics is compensated for by the current having the negative temperature characteristics of -1000 ppm / ° C, and the magneto-electric conversion characteristics of the Hall elements 2 and 3 are -500 ppm / It is made to exhibit a temperature dependence of not more than ° C.
[0038]
As described above, in the above embodiment, the temperature dependence of the magneto-electric conversion characteristics of the Hall element is reduced by using the constant current source instead of the constant voltage source as the drive circuit of the Hall element. In addition to compensating with the characteristics, the temperature dependence of the resistor that generates the threshold level of the comparator that discriminates the output of the Hall element is compensated by the negative temperature characteristic of the constant current source that gives the current flowing through the resistor. It is not necessary to use a high voltage even in a high temperature region, and a constant current source having a negative temperature characteristic as described above can be easily realized on a silicon chip, so that it can operate in a wide temperature range. There is an effect that a monolithic IC sensor can be provided at low cost.
[0039]
Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the invention. Nor. For example, in the above-described embodiment, the dummy Hall element 3 is provided and its output average value is taken to give an operating point to the comparator 7. However, the operating point of the comparator is not limited to this, and any stable level can be set. It can be used. In the embodiment, the peak hold circuit 8 and the conductance amplifier 9 are provided to remove the DC level from the output of the Hall element. However, these circuits can be omitted.
[0040]
In the above description, the case where the invention made by the present inventor is mainly applied to a magnetic sensor using a Hall element, which is a field of application as the background, has been described. However, the present invention is not limited to this, and the present invention is not limited thereto. The temperature compensation circuit in the circuit can be generally used.
[0041]
【The invention's effect】
The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.
[0042]
In other words, it is necessary to compensate for the temperature dependence of the magneto-electric conversion characteristics of the Hall element and to manufacture a monolithic IC sensor having a Hall element and its peripheral circuits on a single silicon chip, which can be driven at a low voltage at a low cost. As a result, it is possible to provide a sensor suitable for detecting rotation of a transmission, an engine, and the like of an automobile operable in a wide temperature range.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a magnetic sensor according to the present invention formed into a monolithic IC.
FIG. 2 is a sectional view showing an example of a structure of a Hall element on a chip of the magnetic sensor IC according to the embodiment.
FIG. 3 is a circuit diagram showing a specific example of a comparator in the magnetic sensor according to the embodiment.
FIG. 4 is a circuit diagram showing a specific example of a current source in the magnetic sensor according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Silicon chip 2 Hall element 3 Dummy hall element 4 Constant voltage power supply circuit 5 Constant current source 7 Comparator 6, 9 Amplifier 10 Output transistor 11 Band gap reference voltage generation circuit

Claims (5)

A Hall element, a first constant current source for supplying a drive current to the Hall element, a comparator for discriminating the output of the Hall element , and a current flowing to a threshold generation resistor for generating a threshold level of the comparator. A magnetic constant detection circuit comprising a second constant current source for
Said first constant current source, the magnetic of the Hall elements - have a predetermined negative temperature characteristic corresponding to the positive temperature dependence of the electrical characteristics of the Hall elements by the temperature characteristics of the negative magnetic - electric Configured to compensate for the positive temperature dependence of the conversion characteristic,
It said second constant-current source has a predetermined negative temperature characteristic corresponding to the positive temperature dependence of the threshold generating resistors, the positive temperature dependence of the threshold generating resistor by the temperature characteristics of the negative A magnetic detection circuit characterized in that the magnetic field is compensated for . The magnetic detection circuit according to claim 1 ,
The Hall element is connected in series with a first transistor constituting the first constant current source ,
The comparator is configured to include the above threshold generating resistor and a second transistor constituting the second constant current source for supplying a current to said threshold generating resistor,
The first transistor is current mirror-connected to an output transistor of a first temperature compensation current source having a predetermined negative temperature characteristic corresponding to the positive temperature dependency of the Hall element, and the first temperature compensation current the negative temperature characteristic of the source magnetic the Hall element - is configured as a positive temperature dependence of the electrical characteristics is compensated,
The second transistor is current mirror-connected to an output transistor of a second temperature compensation current source having a predetermined negative temperature characteristic corresponding to a positive temperature dependency of the threshold generation resistance, and the second temperature compensation is performed. A magnetic detection circuit, wherein the positive temperature dependency of the threshold generation resistance is compensated by a negative temperature characteristic of a current source . The magnetic detection circuit according to claim 2,
The second temperature-compensating current source includes a third transistor that is connected in a current mirror with the second transistor, a resistor that is connected in series with the third transistor, and a current mirror that is connected to the third transistor. A fourth transistor connected thereto, and a reference voltage generating circuit connected in series with the fourth transistor,
A magnetic detection circuit, wherein a temperature characteristic of the resistor is substantially equal to a temperature characteristic of the threshold generation resistor, and a voltage generated from the reference voltage generation circuit is applied to the resistor . 4. The magnetic detection circuit according to claim 1, wherein the first constant current source has a negative temperature characteristic of about −1000 ppm / ° C., and the second constant current source has a negative temperature characteristic of about −1000 ppm / ° C. 5. Wherein the temperature characteristic is about -2000 ppm / ° C. In the magnetic detection circuit according to any one of claims 1 to 4, that the Hall element and the comparator and the first and second constant current source and is formed on one of the single-crystal silicon chip A magnetic detection circuit .

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