JPS5823749B2 - Monolithic integrated current source - Google Patents

Description

[Detailed description of the invention] Transigitron's internal bulletin ``''SASCOImf
Ormation"No. 2, Paper written in 1969"
'TTL-Schaltungen m it K
from ``lemmdiode'') ``Hand bo''
ok of Sem 1conductorE 1ek
troni es” Volume 3 XMe Graw-Hll
l BookCom pany, 1970, 11-
From the article by L. Hunter on page 40, it is possible to prevent the switch transistor from turning on or off at high operating temperatures by connecting a diode that operates in the forward or reverse direction in parallel between the emitter and base of the switch transistor. Methods are known to leak or channel the reverse leakage currents that are responsible for ensuring this.

Furthermore, from British Patent No. 1,180,284, instead of a forward-acting diode as the element that leaks or conducts reverse leakage current between the emitter and base of the switch transistor, a collector-base short circuit of the same type as the switch transistor is used. It is also known to connect transistors in parallel.

In this case, the emitter-base of this leakage transistor forms a forward operating diode.

Furthermore, British Patent No. 769584 and British Patent No. 8
91229 also discloses a method of connecting transistors with open bases in parallel as leakage elements between the emitter and base of switch transistors.

All these configurations are intended to ensure that the switch transistor has satisfactory switching characteristics at high operating temperatures.

In contrast, the invention relates to a monolithically integrated current source having an npn (npn) transistor whose emitter is connected to the negative pole of a voltage source.

This kind of current source is U, Tietze, Ch, 5ch
Text co-authored by Enk “Halbleiter-S”
chatlmgste-chnik” 2nd edition (19
71), p. 112, Figure 6.45.

In this type of current source, the reverse leakage current flowing into the substrate diode of the npn transistor causes
A problem arises in that the value of the output current, which should originally be kept constant, increases as the temperature rises.

Therefore, an object of the present invention is to make the output current of the current source as temperature-independent as possible in the current source described as the essential concept of the claims.
) The purpose is to compensate for reverse leakage of the transistor into the substrate.

This problem is solved in the following manner in the present invention.

In a monolithically integrated current source comprising a vertical npn (npn) transistor, the emitter of which is connected to the negative pole of a voltage source, a first and a second collector are connected to a single semiconductor substrate. 1
A second pnp (pnp) transistor is configured by integrating a pnp (pnp) transistor as a transistor, a second pnp (pnp) transistor is configured from the electrode of the first pnp) transistor itself and the semiconductor substrate, and the emitter of the first pnp) transistor is connected to a voltage source. electrically connect the first collector to the positive electrode of the vertical npn
) connected to the collector of transistor, lateral pnp )
A second pnp between the second collector and the base of the transistor
) transistors, the base of the first pnp transistor being connected to the emitter of the second pnp transistor, and the base of the second pnp transistor being connected to the first pnp transistor.
np) connected to the second collector of the transistor, and the second pn
p) The collectors of the transistors were connected to a common substrate of a monolithically integrated current source and their sterilization was performed.2pnp) The transistors were constructed either in the form of lateral transistors or vertical substrate transistors.

Furthermore, according to the invention, the third pnp) transistor is provided as a lateral transistor integrated in a single semiconductor substrate, and the first pnp) transistor is configured as a lateral transistor, with the collector of the third pnp) transistor being connected to the third pnp) transistor as a lateral transistor. 1 pnp) transistor, and the emitter of the third pnp) transistor was electrically connected to the negative electrode of the voltage source.

Next, embodiments of the present invention will be described in detail using the drawings.

In the embodiment of FIGS. 1-3, the emitter of the current source npn) is connected to the negative pole 2 of the voltage source.

In this case, the collector of the transistor 70 immediately compensates for the reverse leakage current 73 flowing onto the substrate of the current source npn), that is, the reverse current 73 that flows in the substrate diode 72 and is detrimental to the output current 71. This assumes that you can do it.

For this purpose, the embodiment of the invention uses a compensation circuit that supplies compensation current 74.

This compensation current is derived from the reverse leakage current of the compensation element and is approximately equal to the reverse leakage current 73 flowing to the faulty substrate.

The compensation circuit, as shown in FIG. 1, comprises one lateral pnp transistor 76 whose emitter is conductively connected to the positive pole 4 of the voltage source.

The lateral transistor 76 has two collectors, one of which is connected to the npn transistor 70.

Lateral pnp) The second collector and base of Langistav 6 are interconnected.

This makes it possible to significantly reduce the influence of current amplification factors caused by product variations.

If both collectors are of equal size, the current amplification of the negative feedback device is relatively constant, somewhat below 1, so that in most cases the pnp) n-type base layer of the transistor TO When the size of the n-type collector layer is made equal to that of the n-type collector layer, the reverse leakage current 77 to the substrate sufficiently compensates for the reverse leakage current 73 to the substrate.

As shown in FIG. 2, by inserting and connecting a pnp transistor 78 with good amplifying action, preferably a vertical substrate transistor, into the negative feedback loop, the influence of the current amplification degree of the lateral transistor 76 can be almost completely removed. Can be done.

If the reverse leakage current 77 into the substrate of the lateral transistor T6 is absent in this device, the compensation current T4 will be equal to the reverse leakage current flowing into the pnp substrate diode 80 of the transistor 78.

For accurate compensation of the reverse leakage current 73 into the substrate of the current source transistor 770, it is only necessary to make the base layer of the pnp transistor 8 the same size as the collector layer of the transistor 70.

However, the reverse leakage current 77 flowing through the substrate diode T5 of the lateral transistor 76 disturbs the accurate balance of current; furthermore, this reverse leakage current has a magnitude of: pnp of the base current of the lateral transistor 76) It may become so large that nothing remains for the emitter current of the transistor, so that transistor T8 is cut off.

These difficulties are obviated in accordance with the present invention by providing another lateral pnp transistor 81, as shown in FIG.

This transistor still supplies an amplified reverse current 82 to the substrate, which flows into its substrate diode 83, to compensate for the reverse current 7T to the interfering substrate;
Ensure emitter current for

Furthermore, lateral transistor 81 supplies a collector-emitter reverse current that approximately compensates for the collector-emitter reverse current of lateral transistor 16 .

In the embodiment shown in FIG. 3, the compensation current 74 is pnp)
It is exactly equal to the reverse current 79 to the substrate of Langistav 8.

By making the base layer of this transistor 78 equal in size to the collector layer of current source transistor 70, the reverse current 73 into the substrate of this transistor is well compensated.

Next, the aforementioned transistor? 0.76, 78, 81 on a single semiconductor substrate will be described.

Japanese Patent Publication No. 41-5656 discloses a method of constructing transistors using monolithic integration technology.

6, 7, and 8 of this known document show how the lateral pnp) transistor T1 and the vertical np
n) transistor T2 are integrated on one common substrate 10.

FIG. 9 of the same specification (FIG. 4 of the present application) shows three transistors T, , T2 . An integrated configuration of T3 is shown, where transistor T□ is a lateral pnp) transistor and transistors T2 and T3 are each a vertical np
pn) is a transistor.

The leakage current 73 of transistor 70, which is to be compensated according to the invention, flows in the opposite direction through substrate diode T2 in FIGS. 1-3.

In FIG. 4, the diffusion layer of transistor T2 (npn) is
It is formed by the n-type layer 12b and also forms the collector region of this transistor T2.

N-type layer 12bI! p with the ip type substrate 10
It forms an n-junction and is designated as a 'substrate diode' and is used for electrical isolation of layer 12b from substrate 10.

However, in reality, a leakage current 13'', which is a parasitic current, flows in the reverse direction through this substrate diode.

Since this parasitic current becomes a non-negligible value especially as the temperature increases, it is compensated for by the technical configuration of the present invention.

For this purpose, the transistors 76 and 78 are additionally connected, or the transistors 76, 78, 81 are additionally connected.

Transistors 76 and 81 are then lateral pnp
) transistor T1 in FIG.
corresponds to the structure of

Transistor 78, on the other hand, can be constructed as a pnp lateral transistor or as a vertical pnp substrate transistor.

The transistor 78 can be configured as a vertical substrate transistor.
8 can be connected to ground or to the substrate 13, so that this b collector can be formed by the substrate 13 itself of the monolithic circuit arrangement.

The equivalent of this simplified transistor 78 is
The transistor T1 shown in FIG. 4 is a vertical substrate transistor as a ``parasitic transistor''.

That is, this parasitic transistor is a pnp transistor T□
An n-type base of is formed at transistor T1 by forming a p-n junction with a p-type substrate.

That is, this parasitic transistor is composed of the emitter of the transistor T1, its base, and the substrate serving as the collector.

As is clear from FIG. 4, when the collector region of the lateral pnp configuration of the transistor T1 is removed, a vertical operation transistor, a so-called vertical pnp substrate transistor, is formed from the p-type emitter region and the p-type substrate of the remaining transistor T1. is configured.

Such a vertical pnp substrate transistor can be advantageously used as transistor 78 in the device of the present invention.

This is because the collector of the transistor 78 can be connected directly to the substrate 13 or to ground, that is, it can be formed from the substrate itself.

This allows the area of the base region to be reduced, thereby saving chip area.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a current source with a compensation circuit having only one pnp transistor, Fig. 2 is a circuit diagram of a current source with a compensation circuit having only one pnp transistor;
Schematic diagram of a current source with a compensation circuit consisting of transistors,
FIG. 3 is a circuit diagram of a current source consisting of three pnp (pnp) transistors, and FIG. 4 is a diagram of an integrated structure of transistors. 10.13...Substrate, 12b...N-type layer, 73.77.79.82...Reverse current to substrate, ? 2.75.80.83...Substrate diode, 74...Compensation current, 76.81...
Lateral transistor, p...p-type layer, N...n-type layer, T,,T,,T3...transistor.

Claims (1)

Claims: In a monolithically integrated current source comprising a vertical npn (npn) transistor, the emitter of which is connected to the negative pole of a voltage source, a first and a 1st with 2 collectors
pnp) Lateral I as a transistor]np) The transistor 6 is integrated and configured, and the first p
np) electrically connect the emitter of the rangestaff 6 to the positive pole 4 of the voltage source, connect the first collector to the collector of the vertical npn) rangestaff 0, lateral pnp) connect the second collector of the rangestaff 6 between the second collector and the base
p) connecting the transistor T6, in which the base of the first pnp transistor T6 is connected to the emitter of the second pnp transistor 8, and the base of the second pnp transistor T6 is connected to the second collector of the first pnp transistor 6; , 2nd pnp) connecting the collectors of the lungistaphs 8 to a common substrate 13 of the monolithically integrated current source, characterized in that the sterilization of the 2pnp) lungistaphs 8 is configured either in the form of a lateral transistor or a vertical substrate transistor. A monolithically integrated current source. 2) the third pnp) transistor 81 is provided as a lateral transistor integrated in a single semiconductor substrate; the first pnp) transistor 6 is configured as a lateral transistor, with the third pnp transistor 8
2. A monolithic integrated current source as claimed in claim 1, wherein the collector of the first pnp transistor is electrically connected to the base of the first pnp transistor, and the emitter of the third pnp transistor is electrically connected to the negative pole of the voltage source.