JPH0770932B2 - Current mirror circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a current mirror circuit having a large current capacity used in a semiconductor integrated circuit device.

[Conventional technology]

Fig. 2 shows the most commonly used horizontal PNPs that are often used in the past.
It is a figure which shows the current mirror circuit which used the transistor. In this figure, 1 is a CB short type lateral PNP transistor (hereinafter L-PNP) in which a collector and a base are connected.
TR) whose base and emitter are L-PNPTR2
Biasing the base and emitter respectively.

When a current I _{1 is} passed through L-PNPTR1, its base-emitter voltage V _BE1 is generally It is represented by. K is the Boltzmann constant, T is the absolute temperature, q is the charge amount, and I _S is the leak current in the base-emitter reverse direction.

Here, the emitter area of the other L-PNPTR2 is
When the same process is performed in the same chip in the same process as above, the current I ₂ which is the collector current of L-PNPTR2 is It is represented by.

That is, since the leak current I _S is the same in the same emitter area and the same process, the same base-emitter voltage V _BE and leak current I _S as L-PNPTR1 are given to L-PNPTR2. A current I ₂ equal to the current I ₁ will flow as a collector current.

[Problems to be solved by the invention]

In the conventional current mirror circuit as described above, the L-PNPTR1, 2 used for constructing the circuit are generally composed of an emitter 3, a collector 4 and a base 5 shown in the sectional structure of FIG.
Similarly, as shown in FIG. 3, a current flows laterally as compared with a vertical NPN transistor (hereinafter referred to as V-NPNTR) in which a current composed of an emitter 6, a collector 7 and a base 8 flows vertically. As shown, the current amplification factor h _FE was small and the current capacity was also small. Therefore, when increasing the current capacity, as shown in FIG.
You have to connect several PNPTR1 and 2 in parallel,
There is a problem that the chip area becomes large as compared with the case where the current mirror circuit is configured by using V-NPNTR.

The present invention has been made to solve such a problem, and an object of the present invention is to obtain a current mirror circuit capable of increasing the current capacity without increasing the chip area.

[Means for solving problems]

The current mirror circuit according to the present invention is a multi-collector type in which the collector is divided into two equal parts, the bases are connected in common, the emitters are connected to the power supply, and one of the collectors is connected to the base. 2 horizontal PN
A P-transistor, a first vertical NPN transistor having a base connected to the other collector of the first horizontal PNP transistor, and a collector connected to a power supply, and a second horizontal PNP transistor.
Connect its base to the other collector of the transistor,
A vertical PNP transistor in which the collector is installed by connecting the collector to the power supply and connecting the base to the emitter of the first vertical NPN transistor and the emitter to the base of the first horizontal PNP transistor. It is composed of and.

[Action]

In the present invention, the first lateral PNP transistor and the first vertical NPN transistor, and the second lateral PNP transistor and the second vertical NPN transistor are Darlington-connected.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the current mirror circuit of the present invention. In this figure, 11 and 12 are L-PNP TRs as lateral PNP transistors, one of the multi-collectors divided into two equal parts is connected to the base. Reference numerals 13 and 14 are V-NPNTRs serving as the first and second vertical NPN transistors, and 15 is a V-PNPTR serving as the first vertical PNP transistor.

Next, the operation will be described.

Since each collector is divided into two equal parts, the divided collector currents I _c11 / 2, I _c12 / 2 flow back to each base and flow to L
Since most of the divided collector currents I _c11 / 2 and I _c12 / 2 flow to the bases of the -PNP TR11 and 12 transistors, the current amplification factor h _FE of these L-PNP TR11 and 12 is almost 1. That is, for one collector current I _c11 / 2, I _c12 / 2 connected to the base, the other collector current is I _c11 / 2.
2, I _c12 / 2, so the current amplification factor h _FE of L-PNP TR11 and 12 is approximately 1: 1 for this multi-collector division ratio.
h _FE ≈1.

Next, these collector currents _{I c11 / 2, I c12 /} 2 flows as a base current to a large V-NPNTR13,14 capacity, is h _FE times in each V-NPNTR13,14 the current amplification factor h _FE ,
These are emitter currents I _E5 and I _E6 , respectively. Where V-PNP
TR15 uses the base current I _{B11 + 12} and collector currents I _c11 / 2, I _c12 / 2 of L-PNP TR11,12 as the emitter current I _E15 and the collector current I.
_{As c15} , the effect of V-NPNTR13 on the emitter current is 1 / h
_Reduce to _FE15 and flow to GND. Here, L-PNPTR11,12
And the V-NPNTR13,14 is the same emitter area, respectively, the same chip, in the same process be the same h _FE characteristic, the aforementioned Of Since the base-emitter voltage V _BE11 of the L-PNPTR11 which is obtained in the same manner by the theoretical expression is applied to the common base of the L-PNPTR11,12, by driving a current I ₁ as a current mirror circuit, a current I ₁ A current I ₁₄ equal to flows.

That is, in the present invention, the L-PNPTR1
The parallel connection required at the time of increasing the capacity due to the decrease of the current amplification factor h _{FE and} the decrease of the current capacity in 2 and 2 is the Darlington connection using the V-NPNTR13, 14 and V-PNPTR15 having a large current capacity. By doing so, it becomes unnecessary and it becomes possible to increase the capacity.

Generally, in the case of an emitter size of about 25 μmφ, L-PNPTR has a current capacity of about 50 to 200 μA, and if the current exceeds this value, the current amplification factor h _FE remarkably decreases and the characteristics as a current mirror cannot be satisfied. For this reason, when constructing a current mirror of about 1 to 2 mA, it was necessary to connect about 5 to 10 in parallel, but the V-NPNTR has a current capacity of about 1 to 2 mA with an emitter area of about 25 μm square. For,
The chip area can be significantly reduced as compared with the case where a plurality of L-PNPTRs are connected.

In this embodiment, the constant current circuit for transmitting the current on the primary side to the secondary side has been described. Similarly, it is diverted to a constant current circuit or a current drive circuit for giving a bias current to each circuit in the integrated circuit. Is also possible.

〔The invention's effect〕

As described above, the present invention is a multi-collector type in which the collectors are divided into two equal parts, the bases are connected in common, the emitters are connected to the power supply, and one of the collectors is connected to the bases. 2 horizontal PNP transistors, the first vertical NPN transistor whose base is connected to the other collector of this first horizontal PNP transistor, and whose collector is connected to the power supply, and the other collector of the second horizontal PNP transistor. A second vertical NPN transistor with its base connected and a collector connected to the power supply, and its base connected to the emitter of the first vertical NPN transistor, and its emitter connected to the base of the first horizontal PNP transistor. Since it is composed of a vertical PNP transistor that is grounded, a large-capacity and high-performance current mirror without increasing the IC chip area. There is an effect that it constitutes a road.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a current mirror circuit of the present invention, FIG. 2 is a diagram showing a conventional current mirror circuit, and FIG. 3 is a diagram showing a sectional structure of L-PNPTR and V-NPNTR.
FIG. 4 is a diagram showing the relationship between the current amplification factor and the collector current, and FIG. 5 is a diagram showing a current mirror circuit in which a plurality of L-PNPTRs are connected in parallel. In the figure, 11 and 12 are L-PNPTR, 13 and 14 are V-NPNTR, 15
Is V-PNPTR. The same reference numerals in each drawing indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A horizontal PNP in a semiconductor integrated circuit device.
A current mirror circuit consisting of a transistor and a vertical NPN transistor, which is a multi-collector type in which the collector is divided into two equal parts, the bases are connected in common, the emitters are connected to the power supply, and one of the collectors is connected. First and second lateral PNPs in which a base is connected to the base
A transistor, a first vertical NPN transistor having a base connected to the other collector of the first lateral PNP transistor, and a collector connected to the power supply;
Second vertical NP whose base is connected to the other collector of the horizontal PNP transistor of, and whose collector is connected to the power supply
And a vertical PNP transistor having a base connected to the emitter of the first vertical NPN transistor, an emitter connected to the base of the first horizontal PNP transistor, and a collector grounded. Current mirror circuit to do.