JPH059017U - Current mirror circuit - Google Patents

Abstract

(57) [Summary] [Object] To provide a current mirror circuit capable of obtaining an accurate mirror ratio, having no variation in characteristics, and avoiding an increase in the area of an IC chip. [Structure] A first transistor T ₁ and n transistors K ₁ , K ₂ , Kn which are supplied with a base current common to the _first transistor T ₁ and have a common collector and emitter.
In a current mirror circuit in which these transistors are arranged on an IC chip, a common collector of n transistors K ₁ , K ₂ , Kn is separated by a plurality of insulating layers 11. The common collectors of n transistors may be separated by an insulating layer for each transistor, or the common collectors of n transistors may be divided into a plurality of groups and the common collectors of each group may be separated by an insulating layer. You may.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention relates to a current mirror circuit capable of obtaining an accurate mirror ratio.

[0002]

[Prior art]

As shown in FIG. 3, the first transistors T _1, transistor K ₁ common of n the first transistors T ₁ and the common base current is supplied collector and emitter, respectively, K _2,. ． A current mirror circuit having Kn is known. The first transistor T ₁ is an input-side transistor, and the n transistors K ₁ , K ₂ ,. ． Kn is an output side transistor, and for one input side transistor T ₁ , output side transistors K ₁ , K ₂ ,. ． If Kn is 10, the ratio of the input current to the output current, that is, the current ratio is 1:10.

Each transistor forming the current mirror circuit is arranged on an IC chip. FIG. 4 shows an example in which the transistors forming the above current mirror circuit are arranged on an IC chip. One input-side transistor T ₁ is formed and n output-side transistors K ₁ , K ₂ ,. ． Kn is made on the same island with the collector C in common. Reference B indicates the base of each transistor, and reference E indicates the emitter of each transistor.

[0004]

[Problems to be solved by the device]

  According to the above conventional current mirror circuit, the n transistors on the output side are the same. Since the collector C is made common on the island, the transistor on the output side The collector currents of the inverters interfere with each other via the common collector C, and an accurate mirror ratio is obtained. However, there is a problem in that there is a large variation in characteristics.

[0005]   The present invention has been made in order to solve the above-mentioned conventional problems, and an accurate mirror. The ratio can be obtained, the characteristics do not vary, and the area of the IC chip increases. An object of the present invention is to provide a current mirror circuit that can avoid .

[0006]

[Means for Solving the Problems]

  The invention according to claim 1 includes a first transistor and the first transistor. N transistors with common base current and common collector and emitter And a current mirror in which these transistors are arranged on the IC chip. Circuit, the common collectors of the n transistors are connected to a plurality of insulating layers. It is characterized by being more separated.

[0007]   According to a second aspect of the present invention, each transistor is connected between common collectors of n transistors. Each of the stars is separated by an insulating layer. The common collector of the transistor is divided into multiple groups, and an insulating layer is placed between the common collectors of each group. It was separated by.

[0008]

[Action]

  According to the first aspect of the present invention, a combination of n transistors that are output side transistors is used. The common collector is separated by multiple insulating layers, Interference between the collector currents is limited.

[0009]   According to the second aspect of the present invention, the n-side transistors, which are the output side transistors, are shared. Since the common collectors are separated one by one, the collector voltage of n transistors is The streams do not interfere with each other. According to the third aspect of the invention, there are n number of tigers. The number of insulating layers separating the common collectors of the transistors can be reduced.

[0010]

【Example】

  Embodiments of a current mirror circuit according to the present invention will be described below with reference to FIGS. 1 and 2. The circuit configuration itself is the same as the circuit example shown in FIG. Is adopted, and common components are given common reference numerals.

In FIG. 1, one first transistor T ₁ and n transistors K ₁ , K ₂ ,. ． Kn, and these transistors are arranged on one IC chip. The first transistor T ₁ is an input-side transistor and includes n transistors K ₁ , K ₂ ,. ． Kn is an output side transistor. Output side transistors K ₁ , K ₂ ,. ． While Kn is formed on a common land, the input side transistor T ₁ is connected to the output side transistors K ₁ , K ₂ ,. ． It is formed independently of the land of Kn. The n output side transistors K ₁ , K ₂ ,. ． The collector C of Kn is formed over the common land, and each of the transistors K ₁ , K ₂ ,. ． The collector of Kn is separated by the insulating layer 11. Each of the transistors T ₁ , K ₁ , K ₂ ,. ． Kn is composed of a collector C formed on the land, an emitter E formed on the collector C, and a base B formed on the emitter E.

Output side transistors K ₁ , K ₂ ,. ． The base current common to the input side transistor T ₁ is supplied to Kn, and the output side transistors K ₁ , K ₂ ,. ． The collectors and the emitters of Kn are commonly connected to form a current mirror circuit as described with reference to FIG.

According to the above embodiment, n output side transistors K ₁ , K ₂ ,. ． Since each collector C of Kn is separated by the insulating layer 11, the individual transistors are completely separated, the interference between collector currents of the individual transistors is eliminated, and an accurate mirror ratio is obtained. It is possible to obtain a current mirror circuit with no variation.

It should be noted that the n output side transistors K ₁ , K ₂ ,. ． The collectors C of Kn do not necessarily have to be separated by the insulating layer 11 one by one, but the common collectors of the n transistors may be divided into a plurality of sets, and the common collectors of each set may be separated by the insulating layer. . The embodiment shown in FIG. 2 is such an example, and the n output side transistors K ₁ , K ₂ ,. ． The common collector C of Kn is divided into (n / 2) groups, and the common collectors of each group are separated by the insulating layer 21.

In addition, for example, when n = 20, and thus the mirror ratio is 1:20, the collectors of the output side transistors are 10 pairs in 2 groups, 5 pairs in 4 groups, and 4 pairs in 5 groups. Two sets may be separated into 10 sets. In short, the n output side transistors K ₁ , K ₂ ,. ． The collector C of Kn may be separated by a plurality of insulating layers.

[0016]   Thus, the collectors of the n output side transistors are not Even if they are not separated by multiple insulating layers, Mutual interference of the collector currents of the output side transistors is reduced and the mirror ratio varies. Is improved, and the collectors of n output side transistors are turned off one by one. The area of the IC chip can be made smaller than the case of separating by the edge layer. There is an advantage to say.

[0017]

[Effect of device]

  According to the invention of claim 1, the first transistor and the first transistor are provided. Common n-source current is supplied to the collector and emitter. A transistor and a transistor are arranged on the IC chip, and a common collector for the above n transistors is provided. The collector current phase of n transistors is separated by the multiple insulating layers. Mutual interference is limited, an accurate mirror ratio can be obtained, and characteristic variations It is possible to obtain a current mirror circuit without

[0018]   According to the second aspect of the invention, the common collectors of the n transistors are individually The collector currents of n transistors interfere with each other because they are separated. The mirror ratio is more accurate and the characteristic variation is further improved. It is possible to obtain a current mirror circuit capable of In addition, the invention according to claim 3 According to this, the common collector of n transistors is divided into a plurality of groups, and the common collector of each group is divided. The collectors are separated by an insulating layer because they are separated by an insulating layer. The number of insulating layers can be reduced more than in the case, and this reduces the IC chip area. Can be made smaller.

[Brief description of drawings]

FIG. 1 is an enlarged plan view showing an embodiment of a current mirror circuit according to the present invention mounted on an IC chip.

FIG. 2 is an enlarged plan view showing another embodiment of the current mirror circuit according to the present invention mounted on an IC chip.

FIG. 3 is a circuit diagram showing an example of a current mirror circuit.

FIG. 4 is an enlarged plan view showing an example of a conventional current mirror circuit mounted on an IC chip.

[Explanation of symbols]

11 Insulating Layer 21 Insulating Layer T ₁ First Transistor K ₁ Transistor K ₂ Transistor Kn Transistor B Base C Collector E Emitter

Claims (3)

[Scope of utility model registration request] 1. A first transistor, and n transistors each having a common base current supplied to the first transistor and having a common collector and emitter, the transistors being on an IC chip. A current mirror circuit in which the common collectors of the n transistors are separated by a plurality of insulating layers in the arranged current mirror circuit. 2. The current mirror circuit according to claim 1, wherein a common collector of n transistors is separated by an insulating layer for each transistor. 3. The current mirror circuit according to claim 1, wherein the common collectors of the n transistors are divided into a plurality of sets, and the common collectors of each set are separated by an insulating layer.