JPH0426155A - Transistor with current detection function - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a transistor with a current detection function consisting of two transistor sections (main transistor section and sense transistor section) each having an independent base region and emitter region. In order to maintain the advantages of making the regions and emitter regions independent, and also solve the problem of complicating the drive circuit due to not having a single base, a shunt resistor is connected to each base region, and these By using a resistor to divide a common base current at a fixed ratio and applying it to each base region, the base appears to be unified and can be easily driven.

(Industrial Application Field) The present invention relates to a transistor having a current detection function for detecting the magnitude of a main current, and is applicable to various transistors such as bipolar transistors, static induction transistors, and field effect transistors. be.

[Traditional techniques]

Conventionally, multi-emitter transistors are known in which a collector region and a base region are common and a number of emitter regions are provided. When such a multi-emitter type transistor is provided with a current detection function, most of the above-mentioned multiple emitter regions are used as emitters for the main transistor section through which the main current flows, and the remaining minority The emitter region was used as the emitter for the sense transistor section for current detection.

However, in a transistor with a current detection function configured like this, the collector region and base region are common, and only the emitter region is separate. Therefore, when the current value or temperature changes, the main transistor section will change due to the influence of the emitter wiring resistance. The voltage between the base and emitter of each sense transistor changes, and the ratio of the base current transferred to each changes.As a result, the ratio between the main current and the detection current collapses, making accurate current detection impossible. The problem was that it became difficult.

Therefore, the present inventors made the collector region of the main transistor section and the sense transistor section common, configured the base region and the emitter region independently, and transferred the base current to each base region individually from an external circuit to generate a current. We have developed a transistor with a current detection function that enables detection. That is, as shown in FIG. 5, this transistor has a collector C common to the above two transistor parts.
emitter for the main transistor section (main emitter) provided independently from each other; emitter for the EM and sense transistor section (sense emitter) E;
s, a base (main base) BM for a main transistor section and a base (sense base) BS for a sense transistor section, which are similarly provided independently from each other.

According to this configuration, since independent bases (main base BM and sense base Bs) are provided in the main transistor section and the sense transistor section, an external drive circuit is connected to these two bases B, 4, and B. The base current IBM, 185 can be transferred individually from . Therefore, if the ratio of these base currents IBM and llll5 is kept constant, even if the current value or temperature changes, the main current collector current 1c (-main emitter current m
ItM) and the sense emitter current IE which is the detection current
The ratio with s is always constant. Therefore, highly accurate current detection is possible regardless of changes in current value or temperature.

[Problem to be solved by the invention]

In the transistor with current detection function shown in Fig. 5 above,
Since the base regions of the two transistor sections are made independent, it is necessary to transfer the base current IBM,llll5 to the two bases (main base BM and sense base Bs) individually, and in addition, these two base currents 111
M, IBS must always be maintained at a constant ratio. Therefore, such - chemotactic base current IBM, ll1
There is a problem in that the drive circuit for supplying s to each base region becomes complicated.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to achieve the advantages of making the base region and emitter region independent (i.e., high precision regardless of changes in current value or temperature). It is an object of the present invention to provide a transistor with a current detection function, which can easily configure a drive circuit for supplying a base current while maintaining the ability to detect current.

[Means for Solving the Problems] A transistor with a current detection function according to the present invention includes a main transistor section through which a main current flows, and a sense transistor section for detecting the current flowing through the main transistor section. A device characterized in that the collector region of the transistor part is common, the base region and the emitter region are each independent, and a shunt resistor is provided to divide the common base current at a fixed ratio and apply it to each base region. It is.

Here, the above-mentioned shunt resistor may be built inside the element or may be provided outside the element.

Note that the present invention can be realized not only in bipolar transistors but also in electrostatic induction transistors and field effect transistors, and since all of these cases are considered, the above-mentioned "emitter", "base", and " The expression "collector" refers to "source,""gate," and "collector," respectively.
It has a broad meaning that also includes "drain."

[For production]

A common base current supplied to the two transistor sections from an external drive circuit is shunted into a main base current and a sense base current by a shunting resistor, with the main base current flowing to the main transistor section and the sense base current flowing to the sense transistor section. Transferred to the department. In this case, since the ratio of the magnitudes of the respective shunting resistors is always constant, the ratio of the magnitudes of the main base current and the sense base current is also always constant. Therefore, as a drive circuit, there is no need to supply base current to the main base and the sense base individually, and it is only necessary to supply a common base current to the single base above, which simplifies the circuit configuration. You can get away with it.

Moreover, as mentioned above, although the appearance is based on a single base,
Since the base region and emitter region are essentially independent, the operating principle is the same as that of the transistor with current detection function shown in Figure 5, and therefore high accuracy is achieved regardless of changes in current value or temperature. This enables accurate current detection.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional configuration diagram of a bipolar transistor with a current detection function according to a first embodiment of the present invention, and FIG. 2 is a schematic diagram showing the same transistor using circuit symbols.

As shown in FIG. 1, the transistor of this embodiment has two p-type diffusion regions 2 and 3, each serving as a base region, in a predetermined region on the surface of an n-type semiconductor substrate 1, which serves as a common collector region.
are formed separately from each other, and these p-type diffusion regions 2
．． N-type diffusion regions 4.5, which serve as respective emitter regions, are formed in predetermined regions within 3. The surface of the semiconductor region described above is covered with an oxide film 6 such as a silicon oxide film (Si02 film), and two resistors RII for base current shunting made of polysilicon are placed in predetermined areas on the oxide film 6.
M, RIIS is formed.

Furthermore, a resistor RIIM is connected from above the p-type diffusion region 2.3.
, over the RBS and over the n-type diffusion region 4.5,
Electrodes 7a, 7b, and 70.7d made of aluminum or the like are formed through each window formed in the oxide film 6, and electrodes 7a, 7b, and 70.7d made of aluminum or the like are formed from above the resistor RaM to another resistor RIIS in the same manner as above. Electrode 7e made of
is formed.

Furthermore, an electrode 8 is formed on the entire back surface of the n-type substrate 1.

With the above configuration, an npn-type main transistor section T in which the n-type substrate 1, the p-type diffusion region 2, and the n-type diffusion region 4 are used as the collector region, base region, and emitter region, respectively;
An npn type sense transistor section Ts is obtained in which the n type substrate 1, the p type diffusion region 3, and the n' type diffusion region 5 serve as a collector region, a base region, and an emitter region, respectively. That is, the main transistor section TM and the sense transistor section Ts have a common collector region, and have independent base regions and emitter regions. Moreover, one end of the base current shunting resistors RIIM and RIIS is connected to each base region (p-type diffusion region 2.3) of the two transistor parts TMTs, and the other end is connected to a common base electrode 7e. The structure is as follows.

To state this based on Figure 2, collector C is 2
The collector is common to the two transistor sections TM and TS, and the emitter is an emitter (main emitter) EM for the main transistor section TM and a sense transistor section T.
s emitters (sense emitters) E, and the bases are two resistors RIIM and R[lS
They have one end in common, giving the appearance of a single base B above.

Note that the base current shunting resistors R□ and R11s are R□
(Set to be RBS, and transistor part T
If the respective inherent base-emitter resistances of M and Ts are RIIE% and RIE', then RI]E(R11
M, RIIE' (R□).

Here, the size and ratio of the RIIM and RBS can be set as appropriate by determining their layout dimensions (width, length, thickness, shape, etc.). Alternatively, by forming a large number of basic resistors with the same dimensions in advance and connecting them in series or parallel as appropriate, R with the desired size and ratio can be obtained.
It is also possible to obtain 11M and RIIS.

In the transistor with the above configuration, a common base current IB is transferred to the base B from an external drive circuit.
However, the two currents IBM by resistors RIIM and RIIs
, I ms (I IIM) r l1s), and the current 11M is transferred to the base region of the main transistor section TM as a main base current, and the current 111S is transferred to the base region of the sense transistor section Ts as a sense base current. On the other hand, the entire collector current IC flows through the common collector C, and the main base current rl? flows through the main emitter EM. An emitter current (main emitter current) TEN flows in accordance with l, and a minute emitter current (sense emitter current) Its flows in the sense emitter E, in accordance with the sense base current Its.

In this case, the polysilicon resistors forming the two resistors RIIM and R11S have a temperature coefficient, but the resistor R
Since RM and RBS are formed of the same polysilicon resistor, the ratio of their resistance values remains constant regardless of temperature changes. In this way, the resistance RBM.

Since the ratio of magnitudes of RBS is always constant, the ratio of magnitudes of main base current IBM and sense base current IBS is also always constant. Therefore, if the common base current Im supplied to the seemingly single base B from the external drive circuit is constant, the magnitude of the two base currents IRHz I@S will also always be constant. Therefore, as the above drive circuit, the main base B is used as the conventional transistor shown in FIG. This eliminates the trouble of having to individually supply base currents IBM and IIS at a constant ratio to the sense base Bs and the sense base Bs, and it is only necessary to supply a common base current 1++ to the single base B above. A very simple circuit configuration is required.

Furthermore, although the top appears to be a single base B as described above, the base region (P-type diffusion region 2.3) and emitter region (n'' type diffusion region 4.5) are each independent. Because of this configuration, its operating principle is the same as the conventional transistor shown in Figure 5, and highly accurate current detection is possible regardless of changes in current value or temperature.In other words, the shunt resistor RIM , RBS is kept constant, even if the current value or temperature changes, the ratio between the collector current Ic (ζIts), which is the main current, and the sense emitter current rts, which is the detection current, will always be maintained. Since the sense emitter current IES can be maintained constant, the magnitude of the collector current Tc can always be accurately detected based on the measured value of the sense emitter current IES.

Next, FIG. 3 is a cross-sectional configuration diagram of a bipolar transistor with a current detection function according to a second embodiment of the present invention.

In the transistor of this embodiment, the conductivity type of each semiconductor region is reversed from that of FIG. 1 to form a pnp transistor structure, and diffused resistors are used as the shunt resistors R□ and RIS.

That is, as is clear from FIG. 3, two n-type diffusion regions 12 and 13, which serve as each base region, are formed separately from each other in a predetermined region on the surface of the p-type semiconductor substrate 11, which serves as a common collector region. Furthermore, these n-type diffusion regions 12.1
P' type diffusion regions 14 and 15, which serve as emitter regions, are formed in predetermined regions within 3, respectively. Further, in a predetermined region of the surface of the p-type substrate 11, two base current shunting resistors RIM and RBS each made of an n-type diffusion region are formed. The magnitude and ratio of these two resistors RIIN and RIIS can be set in the same manner as in the case of the polysilicon resistor in the first embodiment. The surface of the above semiconductor region is covered with an oxide film 16, and resistors R are applied from above the n-type diffusion regions I2 and 13 through the oxide film 16 formed there.
IM, over Rss and p type diffusion region 14.15
Electrodes 17a, 17b, 17c, 17d and 17e are formed on the upper surface and on the connecting portion of the two resistors RIIM and RBS, respectively, and an electrode 1 is formed on the entire back surface of the p-type substrate 11.
8 is formed.

With the above configuration, the p-type substrate 11, the n-type diffusion region 12,
A pnp type main transistor part TM in which the P type diffusion region 14 is used as a collector region, a base region, and an emitter region, respectively, and a p type substrate 11, an n type diffusion region 13, and a p type diffusion region 15 are used as a collector region and a base region, respectively. Similarly to the first embodiment, the two transistor parts TI4 and Ts have a common collector region and a base region and an emitter region. Each is independent. Then, each base region of the two transistor parts TM and Ts (
The n-type diffusion regions 12 and 13) each have a resistor RIIM,
One end of the RIIS is connected, and the other end is connected to a common base electrode 17e.

If the transistor of this embodiment having the above configuration is shown using circuit symbols, it will be the same as in FIG. 2 except that the flowing directions of the collector current and emitter current are reversed. Therefore, in this embodiment, as in the first embodiment, it is possible to perform highly accurate current detection regardless of changes in current value or temperature, and the drive circuit for supplying the base current is very simple. Can be easily configured.

Note that when forming a resistor by diffusing impurities in the semiconductor region as in this example, the conductivity type, etc. should be taken into consideration when forming the resistor so that the resulting parasitic elements do not adversely affect the original transistor characteristics. is desirable.

Next, as an application example of the transistor with a current detection function of the present invention, an example of an overcurrent protection circuit for protecting the transistor itself from overcurrent is shown in FIG. Note that here, the above-mentioned first transistor is used as a transistor with a current detection function.
The transistor of the embodiment is used.

As shown in the figure, the collector C of the transistor T with current detection function is connected to the positive side of the DC power supply 22 through the load 21, and the main emitter E9 is connected to the negative side of the DC power supply 22 through the common terminal 23. Furthermore, the sense emitter Es is connected to the common terminal 23 via a current detection resistor R8. Furthermore, the seemingly single base B has a common base current 1. output from the transistor drive circuit 24. is now being transferred.

Further, the voltage generated across the current detection resistor RS connected to the sense emitter Es is input to the DC amplifier 25, and the output voltage obtained by amplification here is output from the reference voltage source 260.
It is input to the judgment control circuit 27 together with the reference voltage V REF. An output voltage corresponding to the judgment result of the judgment control circuit 27 is supplied to the control input terminal S of the transistor drive circuit 24 as a control signal.

The specific operation of the overcurrent protection circuit having the above configuration will be explained below.

First, when a drive signal is input to the drive input terminal d of the transistor drive circuit 24, the transistor drive circuit 24 causes the apparent upper base B of the transistor T to have a constant base current 1. supply. Then, this base current I is reduced to two base currents 111 by the two resistors RIIM and RIS.
The current is shunted to M and IBS, and each transistor section'
rs and TS are transferred to their respective base areas (see FIG. 1). As a result, the transistor T becomes conductive, and the collector current IC, which is the main current, flows through the load 21. At this time, a small sense emitter current IES also flows through the current detection resistor Rs, so that the resistor Rs
A voltage is generated across the terminal which is exactly proportional to the magnitude of the collector current 1c. This voltage is amplified by a certain factor in the DC amplifier 25.

The output voltage of the DC amplifier 25 is input to the judgment control circuit 27 and compared with the reference voltage VR[F. If the load 21 is short-circuited for some reason and the collector current IC becomes excessive, the output voltage of the DC amplifier 25 becomes lower than the reference voltage V RE
When it becomes higher than F, the decision control circuit 27 reduces the supply of the base current IIl to the transistor T. Such a negative feedback loop protects the transistor T, the load 21, and the DC power supply 22 from overcurrent.

In each of the embodiments described above, the base current shunting resistor R! l, 4-. Although the case where Rvls is built inside the element is shown, these resistors may of course be provided outside the element. However, when forming the resistors inside the waist element, the two resistors can be formed using the same material and the same process, so it is easier to make the two resistors have the same temperature coefficient. , Therefore, the two base currents r1 obtained by dividing the current through these resistors
It is possible to keep the ratio of the sizes of M and ■8 more precisely and constant. Note that the three means for creating a resistor inside the element are not limited to those shown in each of the above-mentioned embodiments, and are capable of maintaining the ratio of the two resistors to one pair, and that do not adversely affect the characteristics of the transistor. If you don't give,
It doesn't matter what it is.

Furthermore, the present invention can be applied to various transistors such as bipolar transistors, induction transistors, and field effect transistors.

〔Effect of the invention〕

According to the present invention, it is no longer necessary to individually supply base current to two bases (main base and sense base) as in the past, and it appears that a common base current is supplied only to the single base above. Therefore, the drive circuit for supplying the base current can be configured very easily.

Moreover, as mentioned above, although the appearance is based on a single base,
In effect, the main base current and sense base current are shunted at a fixed ratio by the base current shunting resistor and supplied to each base region, so the operating principle is that two base currents and two emitter currents are connected to each other. This is equivalent to a conventional transistor with a current detection function, and therefore highly accurate current detection can be achieved regardless of changes in current value or temperature.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram of a bipolar transistor with a current detection function according to the first embodiment of the present invention, FIG. 2 is a schematic diagram showing the transistor in FIG. 1 using circuit symbols, and FIG. 3 is a diagram of the present invention. FIG. 4 is a cross-sectional configuration diagram of a bipolar transistor with a current detection function according to the second embodiment of the invention, and FIG. 4 is a block diagram showing an example of an overcurrent protection circuit using the transistor of the first embodiment of the invention. The figure is a cross-sectional configuration diagram of a conventional bipolar transistor with a current detection function. ■ ・ ・ 2.3 4, 5 11 ・ ・ 12, 1 14, I Tn ・ Ts ・ C ・ ・ B ・ ・ E9 ・ Es ・ RIIN＼ ・N-type semiconductor base Fi (collector region), ... p-type Diffusion region (base region), ... n type diffusion region (emitter region), p type semiconductor substrate (collector region), 3... n type diffusion region (base region), 5... p type Diffusion region (emitter region)...Main transistor section,...Sense transistor section, -Collector, -Base,...Main emitter,...Sense emitter, RIIS...Resistance for shunting.

Claims (1)

[Claims] It has a main transistor section through which a main current flows, and a sense transistor section for detecting the current flowing through the main transistor section, the collector regions of the two transistor sections are common, and the base region and emitter region are each independent. What is claimed is: 1. A transistor with a current detection function, further comprising a shunting resistor that shunts a common base current at a fixed ratio and applies it to each base region.