DD226697A1 - BIPOLAR DARLINGTON POWER TRANSISTOR - Google Patents

Abstract

The invention relates to a bipolar Darlington power transistor, which is used in particular in the power output stages of integrated circuits. The object of the invention is the realization of a Darlington power transistor, which has very good characteristics with respect to the second breakdown. The technical problem is to find an arrangement for a Darlington power transistor, which has a homogeneous temperature distribution under virtually all operating conditions. The object of the invention is achieved by dividing the Darlington power transistor into a plurality of transistor pairs, consisting of driver subtransistors and power subtransistors, and arranging these subtransistors such that at least one subtransistor of another pair is located between each subtransistor pair. The invention is advantageously used in Darlington power transistors as well as integrated circuits such as NF power amplifiers, power operational amplifiers, voltage regulators and the like. ae. applied.

Description

Prankfurt (Oder), the JK.t-

Inventor: Andrä, Wolfram Dahl, Hans

Title of the invention

Bipolar Darlington Power Transistor

Field of application of the invention

The invention is advantageously used in Darlington power transistors, in particular in the power output stages of integrated circuits, such as IiP power amplifiers, power operational amplifiers, voltage regulator circuits and the like.

Characteristic of the known technical solutions

It is known that power amplifiers of the mentioned fields of application are operated at output currents up to about 10 A and that these output stages consist of a power transistor and a driver transistor connected in front of it in order to keep the required control currents small. It is also known that in order to avoid this local overheating, especially in the center of the large-area power transistor, which can lead to destruction of this transistor by the "second breakthrough", measures are required for homogenization of the temperature distribution within the transistor ·

The insertion of negative feedback resistors, as described in DE-OS 30 17 750, has the goal to implement the different heat conduction conditions corresponding proportions of the total power loss in the individual transistor sub-areas, so that the temperature of all transistor sub-areas is the same. The adjustment of the power loss in the transistor sub-regions via different emitter-base voltages of Transiatorteilgebiete, which in turn are set by the voltage drops across the appropriately sized negative feedback resistors, Since these voltage drops are directly dependent on the collector current of the transistor, it can be seen that a uniform Temperature distribution can only be achieved for a defined operating point of the transistor. For example, if the dimensioning of the resistances for a current I,. so that there is a uniform temperature distribution, then at a current I ₂ > I * will set a temperature increase in the transistor sub-areas, which are associated with the smallest negative feedback resistance; This is usually the case for the transistor edge regions. A current I ^ I * results in a temperature increase in the transistor subareas with the largest negative feedback resistors. The solution described in DE-OS 28 22 166 is less than approximately 500 microns for emitter fingers Applicable only if no additional area requirement, if the surfaces free by the shortened emitter fingers in the center of the transistor can be used as contacting surfaces. This can not be realized in many cases, especially in power transistors in integrated circuits, and thus represents a substantial restriction of the design conditions The power transistors with emitter fingers of length greater than ca, 500 / um makes an additional increase in the distances between the emitter fingers e'r for borrowed, which leads to an ineffective increase in area of the power transistor · The previously known Solutions for the realization of a homogeneous

Temperature distribution within a power transistor is thus only applicable for limited operating and design conditions.

Object of the invention

The object of the invention is to provide a Darlington power transistor which largely avoids these disadvantages,

Explanation of the essence of the invention

The technical problem to be solved is to realize a Darlington power transistor, which has a virtually homogeneous temperature distribution with minimal space requirement under virtually all operating conditions, even with technologically induced irregularities. According to the invention the object is achieved in that, in contrast to previously known solutions, which are limited only to an improvement of the power transistor, the Darlington power transistor is divided into a plurality of transistor pairs, consisting of driving partial transistors and power subtransistors, and these subtransistors are arranged so in that there is at least one partial transistor of another pair between each partial transistor pair. In this way it is achieved that the respective driver partial transistor of a pair is largely thermally decoupled from the power part transistor electrically associated therewith due to the spatial distance and the associated thermal resistance and at the same time a good thermal coupling to a power sub-transistor of another pair is achieved. This causes that at an above-Erv / Mrmung of a power transistor part of the thermally coupled to him driver subtransistor also experiences a temperature increase, during which this power subtransistor electrically associated

Driver subtransistor is heated to a much lesser extent.

For a given base-emitter voltage of the Darlington power transistor, the current in the sub-transistor pair whose driver sub-transistor is heated more is increased. "For a given current of the Darlington power transistor, the current of the power sub-transistor assumed to be above average increases to the same extent From and thus there is a redistribution of the currents in the sub-transistor pairs in such a way that all the sub-transistors are at almost the same temperature level.

Ausführungsbe ispiel

The invention will be explained below with reference to two exemplary embodiments with reference to the drawings,

Embodiment 1

Pigur .1 shows a schematic representation of a Darlington power transistor according to the invention, the .j of two driving section transistors T ₁ and T p and four power unit transistors L _1, L ₁ 2 * ^L 2 1 ^and ^ 2 2 ^{bes "fcej3 't} · In this case, the illustrated partial transistors are such, preferably produced in epitaxial Planar technology, transistors, as are commonly used in integrated bipolar circuits · These subtransistors have advantageously in integrated power stages an elongated, finger-shaped structure · Figure 2 shows the simplified equivalent circuit diagram of the in Pigur schematically In the example chosen, a subtransistor pair is composed of an npn driver subtransistor, e.g., T ₁ , and two of these controlled parallel connected npn power subtransistors L _{1 Λ} and L _{1 o} .

  · I I · <-

With reference to the arrangement shown in Figure 1 of the partial transistors of a Darlington power transistor according to the invention, it can be seen that between the driver subtransistor T "and the power subtransistor L _{1 i of} the first subtransistor pair the power subtransistor L _{2 2} ^ ^e3 second subtransistor pair is arranged and interposed the driver part transistor T ₂ and the power unit transistor T ₂ and the power unit transistor ₂ L ₂ of the second pair of transistors of the power transistor part L is _{1 Λ} of the first part of the transistor pair.

By this arrangement it is achieved that due to the spatial distance between the driver subtransistor ^ z. B. T ₁ and power transistors, z. B. L _{1 1} and L _{1 2} , a partial transistor pair and the associated thermal resistance between driver subtransistor and power transistor part of this pair a good thermal decoupling exists. On the other hand, as can be seen from Figure 1, a good thermal coupling between the driver subtransistor, z. B. T ₁ , a first pair and the power subtransistors L _{n Λ} and L ₀ ο of the second pair achieved.

I c

_Λ and L ₀

The specific advantages of this arrangement are that under virtually all operating conditions, a uniform temperature distribution is achieved within the Darlington power transistor, Is one z. Example, that the temperature of a power transistor part, z. B. L ₁ .., above average

I · Ί

increased on average, which z. B. by uneven heat dissipation within the entire system of the Darlington power transistor or irregularities of technological or constructive type is possible, it will also experience a temperature increase by the good thermal contact of the power transistor part L _{1 1} to the driver part transistor T ₂ . This increase in temperature causes an increase of its emitter current, whereby the power transistor part L _{0 1} and L ₀ are driven more. For a given total current through the Darlington power transistor thus takes place a redistribution of

Currents between the power subtransistors so that the power subtransistors L ₂ ^ uncTLg _{2 take} ^a greater share of Gesarntstrotnes and consequently the current in the power subtransistor L. ₁ is reduced accordingly · Since the power losses in the power subtransistors are proportional to the collector currents flowing in them, therefore also finds a redistribution of Gesatntverlustleistung and thus the temperature between the power sub-transistors, so that the originally assumed temperature increase in the power sub-transistor L ₁ .. is regulated in this way ·

Embodiment 2

From that set forth in Embodiment 1 is easy to recognize that the temperature compensation between the subtransistors of a Darlington power transistor is the more perfect the greater the number of these subtransistors and the better the thermal decoupling between the driver subtransistors and the power subtransistors of a pair and The thermal coupling between the driver subtransistors of one pair and the power subtransistors of other pairs is thus. It is advantageous to arrange Darlington power transistors for larger maximum currents, eg, greater than 5 A, such that a division into driver subtransistors is also performed in the Pinger direction and power subtransistors occurs. A schematic representation of such a Darlington power transistor, which consists of 6 driver subtransistors and 12 power subtransistors, is given in Figure 3. The simplified equivalent circuit diagram of this arrangement is shown in Figure 4 The arrangement of the driver subtransistors to the corresponding power subtransistors takes place in principle as explained in detail in Example 1, ie. the driver subtransistor T ₁ is thermally decoupled from the power subtransistors L ₁ and L ₁ 2 and forms a subtransistor pair with these. At the same time, there is a good thermal coupling behavior.

between the driver subtransistor T ^ and the power subtransistors Lg .. and Lg _{2 #} The arrangement of all other subtransistor pairs is analogous.

The required electrical leads and connections between the subtransistors of such a Darlington power transistor are advantageously realized by means of two-level metallization, as it is used in the manufacture of integrated circuits »The mechanism of the current distribution and thus the temperature compensation is analogous to that in the embodiment 1 described 7 / irkprinzip. It can be seen that the temperature compensation in the Darlington power transistor according to this example is two-dimensional, so that such an arrangement is preferably to be applied to Darlington power transistors for larger currents.

Claims (3)

Erfindungsansprueh 1. A bipolar Darlington power transistor with homogeneous temperature distribution, which consists of at least two parallel partial transistor pairs, each of which contains a driver subtransistor or a plurality of parallel driver partial transistors and a power subtransistor or a plurality of power transistor connected in parallel, characterized in that these subtransistors (L and T) so in that there is at least one driver subtransistor (T) and / or power subtransistor (L) of another pair between each subtransistor pair (L; T). 2. Bipolar Darlington power transistor according to item 1, characterized in that between the driver subtransistors (T) and the power subtransistors (L) of a first pair as many subtransistors (L and / or T) of other pairs are arranged, wherein at the same time between the Driver partial transistors (T) of a first pair and the Leistungsangstreibertransistoren (L) of another _pair or several other pairs the smallest possible spatial distance « 3 · Darlington bipolar power transistor according to item 1 and 2, characterized in that the power subtransistors (L) of a first pair whose driver subtransistors (T) have a small spatial distance to the power subtransistors (L) of one or more other pairs of these power subtransistors (L) are arranged as far as possible spatially distant. For this. "... Ssfen ZeSchnunceo