JPH0461416A - High temperature leakage compensation circuit for transistor circuit - Google Patents

Abstract

PURPOSE:To execute high temperature leakage compensation of a lateral PNP transistor(TR) with a small circuit scale by connecting an emitter of a 2nd lateral PNP TR whose base is opened to a collector of a 1st lateral PNP TR. CONSTITUTION:A base of a 1st lateral PNP TR Q1 whose emitter is connected to a power supply Vcc is connected to an input terminal IN. A collector of the TR Q1 is connected to an output terminal OUT and also connected to an emitter of a 2nd lateral PNP TR Q2 whose collector is connected to ground. A base of the TR Q2 is opened. Thus, the effect of a leakage current of the lateral PNP TR is cancelled with a simple circuit and the high temperature leakage compensation circuit for a TR circuit suitable for integrated circuit is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a high temperature leak compensation circuit for a transistor circuit that compensates for leak current of a transistor at high temperatures.

(Prior Art) FIG. 3 shows a conventional high temperature leak compensation circuit described in Japanese Patent Laid-Open No. 1-155712.

In FIG. 3, transistor Q1 is a PNP transistor used for output. Transistor Q2 is a PN whose high temperature leakage current is l/n of transistor Q1.
P transistor. Transistors Q+ and Q2 are both so-called lateral PNP transistors, which are based on an N-type epitaxial layer, with a P-type diffusion layer formed in this epitaxial layer and used as the emitter and collector. It is set to 1/n of the transistor Q1. Transistors Q3, Q and resistors R1, R2 constitute a current mirror circuit as shown, with Q3 being an input transistor and Q4 being an output transistor. Q2 is connected in series between transistor Q3 and power supply VCC. Furthermore, the connector of the transistor Q1 is connected to the collector of the transistor Q4, and is also connected to the output terminal OUT. Note that the base of the transistor Q2 is in an open state and is not connected to anything else.

Resistors R1 and R2 have a relationship of R1:R2=n:1, and the base current of Q3 is n times the base current of Q3. That is, the current mirror ratio is 1:n.

Here, the collector current of transistor Q4 is 11, the collector current of transistor Q1 is 12, and the collector current of transistor Q4 is 11.
If the collector current of is 13 and the output current flowing to the output terminal OUT is IO, then the following relationship holds true. During high-temperature operation, a leakage current flows through the transistor Q1, but its value is n of the leakage current 11 of the transistor Q2.
It's double. Since the current mirror ratio of the current mirror circuit is 1:n, I 3 = n X I 1 . Therefore, the leakage current contained in I2 is absorbed as the collector current of transistor Q4, and the current 1o flowing to the output terminal is
is obtained by canceling the leakage current. In particular, it eliminates the influence of leakage current, which increases significantly at high temperatures due to the characteristics of transistors.

In this way, leakage current of the transistor during high-temperature operation can be absorbed, so a highly reliable transistor control circuit that does not malfunction over a wide temperature range can be constructed.

However, in the conventional leakage compensation circuit described above, it is necessary to prepare transistors Q3 and Q4 forming a current mirror circuit in addition to the PNP L transistor Q2 for monitoring for one PNP transistor Q1 to be compensated. There was a problem that the circuit scale increased.

(Problems to be Solved by the Invention) The conventional circuit described above has the drawback of increasing the circuit scale because a current mirror circuit is required in addition to a leak current monitoring transistor for each transistor whose leak current is to be compensated. was.

This invention realizes high-temperature leak compensation of a lateral PNP transistor with a small circuit scale.

[Configuration of the Invention (Means for Solving the Problems) The high temperature leak compensation circuit for a transistor circuit of the present invention comprises:
a first lateral PNP that is the output stage or part of the output stage;
In a transistor circuit consisting of a transistor and the collector (or emitter) of this transistor connected to an output terminal, the emitter (or collector) of a second lateral PNP transistor whose base is open.
is connected to the collector (or emitter) of the first lateral PNP transistor.

(Function) By the means described above, high temperature leakage compensation of the lateral PNP transistor can be achieved by adding one lateral PNP transistor with the base open, and the leakage current component can be compensated for by using only the lateral PNP transistor with the base open. Can be erased.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In Figure 1, the base of a lateral PNP transistor Q1 whose emitter is connected to the power supply Vcc is the input terminal IN
It is connected to. The collector of the transistor Q1 is connected to the output terminal OUT, and the collector is connected to the emitter of a lateral PNP transistor Q2 whose collector is grounded. The base of transistor Q2 is left open. Dl and D2, which are connected between the bases of transistors Q1 and Q2 and ground with the polarities shown, are parasitic diodes that occur due to the structure of the lateral PNP transistor.

Here, the current 11 flowing through the parasitic diode D1 is the voltage v1 applied to the parasitic diode D1, and the voltage v1 applied to the parasitic diode D1 is
If the saturation current in the reverse direction is ISI, then I + −ISI (exp(V+ /Vy
) is obtained from 1). However, VT is a coefficient with respect to absolute temperature called thermal voltage, and has a value of about 281V at normal temperature. This value is reverse biased when the parasitic diode is normally used, and the bias voltage is usually at least several hundreds of volts. Therefore, the current flowing through the parasitic diode D1 is approximately equal to the reverse saturation current 181 of the parasitic diode D1, as seen from the above equation. This current becomes the base current of transistor Q1, so β11SI (β1 is the current amplification factor of transistor Q1) is applied to the collector of transistor Q1.
This current will flow as a leakage current.

On the other hand, the reverse saturation current IS2 of the parasitic diode D2 connected to the base of the transistor Q2 is
It becomes equal to the reverse saturation current ISI of 1. Since this parasitic diode D2 is normally reverse biased with a voltage of several hundred mV or more, the current that flows is equal to the reverse saturation current IS2 of the diode, as in the case of the parasitic diode D1. This current IS2 becomes the base current of the transistor Q2, so if the current amplification factor of the transistor Q2 is β2, the emitter of the transistor Q2 is
A current of (1+β2) flows. Normally, the current amplification factor of a transistor is sufficiently larger than 1, so the current flowing through the emitter of transistor Q2 is approximately equal to 182·β2.

Therefore, output transistor Q1 and transistor Q
2 with the same shape and pair characteristics, l5I-IS
2. Since it can be regarded as β1-β2, the leakage current component 181·β1 of transistor Q1 can be expressed as
2 leakage current component ISI・β2 cancels it out, output end city O
The UT is no longer affected by leakage current.

FIG. 2 shows another embodiment of the present invention, and the difference between this embodiment and FIG. 1 is that the positions of transistors Q1 and Q2, whose output sides are connected in series between the power supply and ground, are swapped. Also, the output terminal OUT is connected to the emitter of the output transistor Q1.

Even in this case, if ISI is the reverse saturation current of the parasitic diode D1 between the base and the substrate forming the transistor Q1, this becomes the base current of the transistor Q1. Assuming that the current amplification factor β1 of the transistor Q1 is β1>>1, a current of approximately ISI·β1 flows as a leakage current in the emitter of the transistor Q1.

On the other hand, the reverse saturation current of the parasitic diode D2 attached to the base of the transistor Q2 whose base is open is IS2.
Then, since this becomes the base current of the transistor Q2 as it is, if the current amplification factor of the transistor Q2 is β2, a current of IS2·β flows through the collector of the transistor Q2. Therefore, if transistors Q2 and Ql with the same characteristics are used, β1-β2, l5I-IS2
Therefore, the leakage current component of the transistor Q1 can be canceled.

[Effect of the invention] As described above, according to the present invention, the lateral PN
The influence of the leakage current of the P transistor can be canceled out with a simple circuit, and a high temperature leakage compensation circuit for a transistor circuit particularly suitable for integration into an integrated circuit can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the invention, and FIG. 3 is a conventional circuit diagram. Ql, Q2...Transistor OUT...Output terminal

Claims (2)

[Claims] (1) A transistor circuit including a first lateral PNP transistor that is an output stage or a part of the output stage, and a collector of this transistor connected to an output terminal,
1. A high temperature leak compensation circuit for a transistor circuit, characterized in that the emitter of a second lateral PNP transistor whose base is open is connected to the collector of the first lateral PNP transistor. (2) A transistor circuit including a first lateral PNP transistor that is an output stage or a part of the output stage, and an emitter of this transistor connected to an output terminal,
1. A high-temperature leak compensation circuit for a transistor circuit, characterized in that the collector of a second lateral PNP transistor whose base is open is connected to the emitter of the first lateral PNP transistor.