JPS5950119B2 - hall effect device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Hall effect device, and more particularly to means for compensating unbalanced voltage of a four-terminal Hall element.

As is well known, the Hall element allows a control current to flow in a direction perpendicular to the magnetic field within a magnetic field.
This generates a so-called Hall voltage. In this case, ideally if the magnetic field is zero, no Hall voltage will be generated even if the control current is passed, but in reality some voltage is generated. This voltage is called an unbalanced voltage and causes errors when used in various detection or measurement equipment. 0 Many conventional Hall elements have four terminals, but in order to reduce the above-mentioned unbalanced voltage, it is common to make the pair of Hall output terminals as symmetrical as possible.

Therefore, the unbalanced voltage does not exhibit a fixed polarity, but randomly varies from positive to negative, making compensation for the unbalanced voltage rather difficult. In view of the above points, the present invention provides a Hall effect device that reliably compensates for unbalanced voltage using two four-terminal Hall elements.

In this invention, the polarity of the unbalanced voltage is fixed by intentionally making the pair of Hall output terminals asymmetric.
The basic idea is to use a terminal Hall element.

That is, four-terminal Hall elements whose unbalanced voltage is predetermined to be positive or negative are formed on both sides of a semi-insulating semiconductor substrate, and these two Hall elements are connected in series to cancel the unbalanced voltage. The current applied to each Hall element is set so as to obtain the sum of the Hall voltages. below,
Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows a Hall element wafer of one embodiment. In the figure, 1 is a semi-insulating GaAs substrate doped with Cr and 00, and two 4-terminal Hall elements 2 and 3 are formed by photoetching an n-type GaAs layer epitaxially grown on both sides of the substrate. There is. Only the outline of the Hall element 3 on the back surface is shown by broken lines. 11, 12
are the control current terminal electrodes of the Hall element 2, and 13, 14
is also the Hall output terminal electrode.

As is clear from the figure, the pair of Hall output terminals of the Hall elements 2 and 3 on the front and back surfaces are stepped asymmetrically with respect to the control current path, and one of them is oriented in the direction of the current terminal. The pattern arrangement is such that when rotated by 180 degrees, one overlaps the other. The Hall element wafer thus constructed is mounted on a ceramic substrate 4 as shown in FIG. 2 on which terminal electrodes have been deposited in advance.

21, 22, 23, 24 are terminal electrodes for the Hall element 3 on the back surface, and 31, 32, 33, 34 are terminal electrodes for the Hall element 2 on the front surface.

That is, by placing the wafer shown in FIG. 1 on the ceramic substrate 4 shown in FIG. Connected. The terminal electrodes 11-14 of the Hall element 2 on the front surface are connected to the terminal electrodes 3-34 on the ceramic substrate 4 by wire bonding, respectively.
This state is shown in FIG. Note that the terminal electrodes 23 and 33 are connected by wire bonding, thereby connecting the two Hall elements 2 and 33 provided on the front and back surfaces of the wafer.
3 are connected in series. With this configuration, a power source 25 and a variable resistor 26 are connected between the terminal electrodes 21 and 22, and a power source 35 and a variable resistor 36 are similarly connected between the terminal electrodes 31 and 32, so that the Hall elements 2 and 2 on the front and back surfaces are connected. Control currents in opposite directions are passed through the terminals 3 and a magnetic field H is applied to obtain a Hall output between the terminal electrodes 24 and 34.

Now, if a control current in the opposite direction is applied to each Hall element 2 and 3 without applying the magnetic field H, unbalanced voltages VHO2 and VHO of opposite signs will be generated in the pixel elements 2 and 3 due to the asymmetry of the respective Hall output terminals. , occurs. By adjusting each control current with the variable resistors 26 and 36, the unbalanced voltage VHO
. , VHO, are equal in size, so the terminal electrode 23
, (33) are set to zero potential, no output voltage appears between the output terminal electrodes 24 and 34 as a whole. Next, when a magnetic field H is applied, the Hall output voltages VH, , VH, generated in each element 2 and 3 are the sum of these VH, +VH, and the Hall output voltage VH as a whole is 1 due to the relationship between the magnetic field and the control current. The size is approximately twice as large as that of a single Hall element.

Such a Hall effect device is useful when applied to, for example, a power meter.

That is, the load voltage is input into a transformer to obtain two independent low-voltage outputs, and these are replaced with the control current power supplies 25 and 35 shown in Figure 3, and the load current is passed through the coil of the electromagnet to generate the magnetic field H.
get. As a result, the Hall output VH obtained is proportional to the product of the load voltage and the load current, that is, the power consumption.
As described above, such a watt-hour meter is characterized by extremely high measurement accuracy, particularly in the light load current region, because the influence of the unbalanced voltage of the Hall element is removed. As explained above, the Hall effect device according to the present invention is
Compared to a conventional 4-terminal Hall element alone, it is possible to obtain a Hall voltage that is approximately twice as high, and unbalanced voltage is reliably compensated for.
Excellent measurement accuracy can be obtained when applied to power meters, etc.

In addition, in the Hall effect device according to the present invention, since two Hall elements are formed on both sides of the wafer, it is of course smaller in size than, for example, when two single molded Hall elements are used. Magnetic field strength, temperature, etc. become uniform for the two elements, resulting in high measurement accuracy. Furthermore, control currents in opposite directions are passed through the Hall elements formed on both sides of the wafer, which has the effect of canceling out thermoelectromotive force. Note that this invention is not limited to the above embodiments.

For example, in the embodiment, the unbalanced voltage is reliably offset by controlling the magnitude of the control current, but even if each control current is fixed by the control current power supplies 25 and 26 as shown in FIG. It is possible to compensate for the unbalanced voltage by connecting the variable resistor 41 and the bias power supply 42 to the Hall output terminal and applying an external bias to the Hall output voltage.

[Brief explanation of drawings]

Figure 1 is a diagram showing a Hall element wafer in an embodiment of the present invention, Figure 2 is a diagram showing a ceramic substrate on which the wafer is mounted, and Figure 3 is a diagram showing the wafer mounted on the ceramic substrate. FIG. 4 is a diagram showing a state in which a bias is applied, and FIG. 4 is a diagram showing another embodiment. 1...Semi-insulating GaAs substrate, 2.3...
... 4-terminal Hall element, 11, 12... Control current terminal electrode, 13, 14... Hall output terminal electrode, 4... Ceramic substrate, 21, 22,
23, 24, 31, 32, 33, 34... terminal electrode, 25, 35... power supply, 26, 36...
...Variable resistance, 41...Variable resistance, 42...
...Bias power supply.

Claims (1)

[Claims] 1. Two four-terminal Hall elements whose unbalanced voltage polarity is fixed by asymmetrically arranging a pair of Hall output terminals are formed on both sides of a semi-insulating semiconductor substrate, and these two Hall elements are coupled in series so that the polarities of the respective unbalanced voltages are in opposite directions, and the value of the current flowing through each of the Hall elements is set so as to cancel the unbalanced voltages and obtain a sum of Hall voltages. Hall effect device.