JP2598068B2 - Parasitic current correction circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a parasitic current correction suitable for solving the problem of a lateral PNP transistor due to a parasitic current generated in an integrated circuit device.

(Prior Art) An integrated circuit incorporating the circuit shown in FIG. 2 is used for driving a large current, and its outline will be described. This large current drive circuit is composed of symmetrical A and B, and both are not output at the same time, and are constituted by an inverter and a multi-stage Darlington connection.

That is, the second input as is apparent in FIG. IN-A, IN-B established a diode Q51, Q55 connected forward, resistance A connected to the V _CC terminal, the end portion of the B diode Q51 , Q55 and the PNP transistors Q52, Q56
The resistors C and D are also connected to the base of the inverter to form an inverter.

Next, a multi-stage Darlington circuit is formed by connecting collector-grounded NPN transistors Q53, Q54, Q57 and Q58 to the collector terminals of the PNP transistors Q52 and Q56. , Q5
7, resistors E and F are provided between the bases, and resistors G and H are provided between the resistors E and F and the bases of the common-emitter NPN transistors Q54 and Q58.

Common-emitter NPN transistor Q54, the collector terminal of the Q58 output Out-A, the motor coil phi ₁ as Out-B, connected to phi _2, the output Out-A, counter electromotive force absorbing clamp diode QA in Out-B , QB, and the output terminal thereof are connected to form a common terminal, which is connected to the connection line of the motor coils φ ₁ and φ ₂ and used as a _VDD terminal.

High (High) and low (Lo) are applied to these inputs IN-A and IN-B.
One feature is that the voltage of w) is applied but not output simultaneously as described above.

To form the large current driving integrated circuit described above, a trench isolation (Trench Isolation) is applied to the semiconductor substrate.
Generally, a method of forming a resistor and a bipolar transistor in an island region divided by an isolation region such as a deep N ⁺ region or the like is common.

However, in this integrated circuit, it is inevitable that a grounded parasitic element having a _QLNA as an input is formed between the semiconductor substrate and each impurity region.

(Problems to be Solved by the Invention) When the above-described large current driving integrated circuit is connected to a motor that causes M coupling, a back electromotive force current flows through the coil in accordance with the on-off of the integrated circuit. Flows in the opposite direction, the Sub (substrate) potential floats, and the parasitic transistor becomes O
n occurs, causing abnormal operation during switching.

This abnormal situation will be described as follows: (1) In the integrated circuit pattern shown in FIG. 2, due to the structure of the circuits A and B installed adjacent to each other, the clamp diodes QA and QB and the substrate (P ^- conductivity type) Parasitic Sub PNP Tr is formed and output NPN Tr Q58 for collector and ioverter
Parasitic Sub lateral PNP T between PNP Tr Q52 base and substrate
r occurred and is indicated as _QLNA in the figure. On the other hand, output NPN T
r Parasitic Sub lateral PNP Tr also occurs between the collector of Q54, the PNP Tr for inverter and the base of Q56 and the substrate.
Indicated as _LNB .

(2) The input IN-A of such a circuit has a high (High and abbreviated as H) and a low (Low and abbreviated as L) and the input IN-B has "H" as well. A signal of "L" is input, but when IN-A becomes "H", Q52, Q53 and Q54 are turned off and Out-A becomes "H". It occurs back electromotive force in the coil phi ₁ to the parasitic Sub PNP Tr in clamp diode QA
To float the _ISUB potential.

(3) Out-B installed adjacent to the floating of Sub potential
Operate the parasitic lateral NPN Tr Q _LNA connected to the collector of output IrQ58 (which is “L” in opposite phase). This Q
_{When the LNA} turns on, the base potential of the lateral PNP Tr Q52 drops, and Q52, Q53, and Q54 turn on and Out-
A falls to "L".

(4) When IN-A becomes “L”, a current flows through the coil φ, the back electromotive force crys, the current flowing through the Sub disappears, and the Sub potential drops. Therefore, the parasitic lateral NPN Tr Q _LNA is turned off. PN
The base potential of P Tr52 also returns to “H”.

(5) When Q52 is turned off, Out-A becomes "H" again, and the operations of (2) to (4) are repeated.

(6) This feedback loop is repeated until the back electromotive force energy stored in the coil disappears, causing an oscillation phenomenon.

Contrary to this example, when a potential "H" is applied to the input IN-B and a potential "L" is applied to the input IN-A, the driving which is completely opposite to that described above occurs, and the description is omitted.

Thus, the lateral PNP Tr Q60 applied to the integrated circuit is not subjected to any correction as shown in FIG.

The present invention relates to a novel parasitic current correction circuit that eliminates the above-mentioned difficulties, and more particularly to a circuit that corrects a current based on a parasitic effect generated between an isolation region provided in an integrated circuit and a semiconductor substrate.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve this object, according to the present invention, another lateral transistor of the same conductivity type and base open which connects emitters in close proximity to a certain conductivity type lateral transistor formed on a semiconductor substrate is provided. A transistor is provided, and a grounded-emitter lateral transistor of the opposite conductivity type is formed adjacent to and close to both transistors, and the collector of the other lateral transistor is connected to the base and collector of one of the grounded-lateral emitter transistors of the opposite conductivity type. , The base of the other opposite-conductivity-type grounded-lateral transistor is connected to the collector of another lateral transistor, and the collector is connected to the collector of a lateral transistor of a certain conductivity type.

(Operation) This parasitic current correction circuit forms another lateral PNP Tr with the same characteristics in close proximity to the lateral PNP Tr installed in the integrated circuit where the parasitic current flows, and the parasitic current generated by it forms the original circuit. A method of canceling the parasitic current generated in the lateral PNP Tr used is adopted.

(Example) An example of the present invention will be described in detail with reference to FIG.

As shown in this figure, in this circuit, lateral PNP transistors Q1 and Q2 of a certain conductivity type which are close to each other and have the same characteristics are installed on a semiconductor substrate (not shown) in a conventional manner. On the other hand, Q2 connects the base open and the emitters of both transistors. Furthermore, these two transistors
The collector terminals of Q1 and Q2 are connected to the collector terminals of opposite conductive lateral NPN transistors Q3 and Q4, respectively, and the collector terminal of a certain conductive lateral PNP transistor Q2 is connected to the lateral NPN transistors Q3 and Q4. It is connected to the base, and the collector terminal of a lateral PNP transistor Q1 of a certain conductivity type is used as an output terminal.

In circuit connection with this structure, lateral NPN of reverse conductivity type
The transistors Q3 and Q4 constitute a current mirror circuit.

Therefore, when a parasitic current I _P due to a parasitic effect flows through a certain conductivity type lateral PNP transistor Q1, a similar current flows through Q2. The current I _P of the Q2 are turned back at lateral NPN transistors Q3, Q4 constituting a current mirror circuit, if Nigase parasitic current generated in the lateral PNP transistor Q1 is conductive to GND in this Q3, originally from I _{OUT Will} be proportional to the current I _IN driven by the circuit.

 This relationship is shown by the following equation.

I _OUT = β × (I _IN + I _P ) −I ₁ I ₂ = β × I _P Here, if β of Q3 and Q4 is very large, I ₂ ≒ I ₁ I _OUT = βI _IN + βI _P −I ₁ = βI _IN β: Current amplification factor of lateral PNP transistors Q1 and Q2 I _P : Parasitic current generated by parasitic effect I _OUT : Output Current that is driven by circuit using lateral PNP transistor according to the above equation Outputs current proportional to _IN It is clear that it will be.

In the integrated circuit provided with the above-described correction circuit, island regions electrically separated by so-called separation regions are formed on a semiconductor substrate on which a thermal oxide film is laminated, and a resistor and a transistor are separately formed in each island region. It is manufactured by a known method.

〔The invention's effect〕

As described above, according to the present invention, as described above, an integrated circuit is formed in an island region electrically separated by the separation region formed in the semiconductor substrate, and the lateral type transistor which is inevitable to occur between the separation region and the semiconductor substrate is formed. By installing a parasitic current adjacent thereto as a sensor of a lateral transistor having the same characteristics, and turning it back by a current mirror circuit formed by arranging a lateral transistor of the opposite conductivity type corresponding to both elements, An output proportional to the current obtained by the original circuit is obtained.

Therefore, when this correction circuit is applied to a large-current driving integrated circuit, the above-described parasitic current can be canceled, so that there is a great advantage that the original characteristics can be operated for a long time even when applied to motor control, for example.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a parasitic current correction circuit according to the present invention, FIG. 3 is a circuit diagram showing a main part of the conventional circuit, and FIG. 2 is a diagram of an integrated circuit for driving a large current applied to a motor.

Claims (1)

(57) [Claims] 1. A lateral transistor which has the same conductivity type as a parasitic current sensor and is connected to emitters is installed near a certain lateral conductivity type transistor formed on a semiconductor substrate. An opposite-grounded lateral transistor of the opposite conductivity type is installed near and corresponding to the transistor, the collector of the other lateral transistor is connected to the base and collector of one of the opposite- conductivity type lateral-emitter lateral transistors, and the other is the opposite conductivity type. And a collector connected to a collector of another lateral transistor, and a collector connected to a collector of a lateral transistor of a certain conductivity type.