JPH02121511A - Current mirror circuit - Google Patents

Abstract

PURPOSE:To obtain a current mirror circuit which is extremely stable to the fluctuation of a characteristic by arranging alternately the reference current input bipolar transistors TR and the constant current output bipolar TRs. CONSTITUTION:A current mirror circuit consists of plural bipolar TRs having the same electrical characteristics. For at least one of these bipolar TRs, the emitter electrode is connected to a common power supply terminal with the base and collector electrodes connected to a reference current input terminal respectively by a 1st connection method. For other bipolar TRs, the emitter electrodes are connected to the common power supply terminal with the base electrodes connected to the reference current input terminal respectively by a 2nd connection method. Then the bipolar TRs of the 1st and 2nd connection methods are alternately arranged in the same direction. Thus, the fluctuation of element characteristics if occurs are offset each other since the reference current input bipolar TRs and the constant current output bipolar TRs are laternately arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to slave circuit technology, and is particularly suitable for use in semiconductor integrated circuits.

[Prior Art 1] In electronic circuits, an output current proportional to an input current value is often required, and a current mirror circuit is generally used. A current mirror circuit using a bibolar transistor includes a bibolar transistor with a reference current input whose emitter electrode is connected to a common power supply terminal, and whose base electrode and collector electrode are connected to a base current input terminal.
It consists of a constant current output bipolar transistor whose emitter electrode is connected to a common power supply terminal and whose collector electrode is connected to a constant current output terminal.
A bipolar transistor having the same electrical characteristics as the transistor is used. If you want to obtain an output current that is m/n times the input current, use n reference current input bipolar transistors and m (11 constant current output bipolar transistors).
A desired output current can be obtained using a transistor. When creating such a current mirror circuit, conventionally, for ease of wiring, n reference current input bipolar transistors are arranged side by side on one side, and m constant current output bipolar transistors are arranged side by side on the other side. The method of arranging has been used. In order to obtain exactly m/n times the output current, the characteristics of each bipolar transistor used must be completely the same.

In general, when semiconductor integrated circuits are fabricated, it is possible to obtain bipolar transistors with relatively uniform characteristics within the same chip. However, due to uneven manufacturing conditions and uneven operating temperatures, the characteristics of each element can vary. It is inevitable that a characteristic change of about 0.5% to 1.5% will occur in Figure 2.
In a current mirror circuit according to conventional technology, for example, m=
4, the case where n=3 is shown. 01 placed on the left side
~Q3 is a reference current input, and 04~Q7 placed on the right side of the bipolar transistor are constant current output bipolar transistors. Due to uneven manufacturing conditions and temperature, the characteristics of 01 on the left end fluctuate by +1.5%, and moving towards the right, the characteristics of Q2 +1% and the characteristics of Q3 +0.5%.
, Q4 in the center has no characteristic change, and when Q5, Q6, and Ql change by -0.5%, -1%, and -1.5%, respectively, the reference current changes by +3% and the output current changes by 13%. So,
There is a 6% variation in input versus output.

[Problems to be Solved by the Invention] The present invention attempts to solve the drawbacks seen in the prior art. Variations in device characteristics do not occur randomly, but are deeply related to the placement location and direction. The aim of this study is to eliminate the effects of characteristic fluctuations by improving the method of arranging elements.

[Means for Solving the Problems 1] The current mirror circuit of the present invention is composed of a plurality of bipolar transistors having the same electrical characteristics, and at least one bipolar transistor among the plurality of bipolar transistors has an emitter. The at least one other bipolar transistor is connected by a first connection method in which the electrode is connected to a common power supply terminal and the base electrode and the collector electrode are connected to a reference current input terminal.
The bipolar transistor of the first connection method and the bipolar transistor of the second connection method are connected by a second connection method in which the emitter electrode is connected to the common power supply terminal and the base electrode is connected to the reference current input terminal. The transistors are arranged alternately and in the same direction.

[For production]

According to the above configuration of the present invention, even if the characteristics of the device vary, the reference current input bipolar transistors and the constant current output bipolar transistors are arranged alternately, so the characteristic changes are canceled out and a stable constant is maintained. Current output can be obtained.

[Example] FIG. 1 shows an example of the present invention, where m=4. The arrangement of bipolar transistors is shown for n=3. Ql-Q
3 is a reference current input bipolar transistor, and Q
4 to Q7 are constant current output bipolar transistors. Similar to the conventional example, the characteristic of 04 on the left side changes by +1.5%, and then towards the right, the characteristic of Ql is +1%, the characteristic of Q5 is +0.5%, the characteristic of 02 in the middle is unchanged, and the characteristic of Q6 is changed by +1.5%. If the characteristic changes to -0.5% and the characteristic of Q3 changes to -15%, the reference current input bipolar transistors Q1 to Q3
The total characteristic variation of is 0%, and the characteristic variation of constant current output bipolar transistors Q4 to Q7 is also 0%, so it is clear that the ratio of input current to output current is kept constant at 3:4. It is. FIG. 3 shows a second embodiment of the present invention, where m=6, n=2, and the input current to output current is 1=3. In this case as well, variations in the characteristics of each element caused by non-uniform manufacturing conditions or non-uniform temperatures can be offset, and a stable constant current output can therefore be obtained.

〔Effect of the invention〕

As described above, by alternately arranging reference current input bipolar transistors and constant current output bipolar transistors, it is possible to obtain a current mirror circuit with extremely high stability against fluctuations in characteristics.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing one embodiment of the current mirror circuit of the present invention, in which 1 to 3 are reference current input bipolar transistors Ql-03, and 4 to 7 are constant current output bipolar transistors.
Transistors Q4 to Q7゜O are reference current terminals, 11 is a constant current output terminal, and 12 is a common power supply terminal. Fig. 2 is a configuration diagram showing a conventional current mirror circuit, and Fig. 3 is:
It is a block diagram which shows the 2nd Example of this invention, and 8-9 are constant current output bipolar transistors 08-Q9. That's all

Claims (1)

[Claims] consisting of a plurality of bipolar transistors having the same electrical characteristics, at least one bipolar transistor among the plurality of bipolar transistors:
The emitter electrode is connected to a common power supply terminal, and the base electrode and the collector electrode are connected to a reference current input terminal. The bipolar transistor of the first connection method is connected to the bipolar transistor of the first connection method and the second A current mirror circuit characterized in that bipolar transistors and bipolar transistors connected in the following manner are arranged alternately.