JPS6136383B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switching circuit with a leakage current compensation circuit that compensates for leakage current by integrating a switching circuit using lateral transistors into a semiconductor integrated circuit.

FIG. 1 is a circuit diagram showing a conventional switching circuit using lateral transistors. In the figure, Q ₁ is a lateral switching transistor, Q ₂
is the output transistor, IN is the input terminal, OUT is the output terminal, R ₁ is the resistor, and R ₂ is the load resistor.

Next, the operation of the switching circuit according to the above configuration will be explained. First, when a signal that draws the base current of the switching lateral transistor _Q1 is input to the input terminal IN, the switching lateral transistor _Q1 becomes conductive, and its collector current flows to the base of the output transistor _Q2 . Therefore, output transistor _Q2 also becomes conductive. Therefore, a potential difference is generated across the load resistor _R2 , and an output signal is output from the output terminal OUT. However, if there is a leakage current I _CEO when the switching lateral transistor Q ₁ is cut off, even if there is no signal to draw the base current on the input side, the leakage current becomes the base current of the output transistor Q ₂ , and this output transistor Q ₂ becomes It becomes conductive and malfunctions.

Therefore, in order to compensate for leakage current, conventionally,
A circuit shown in FIG. 2 has been proposed. That is,
FIG. 2 is a circuit diagram showing a conventional switching circuit with a leakage current compensation circuit. In the same figure, Q ₃
is a transistor, _Q4 is a diode, and _R3 is a resistor.

Note that the transistor Q ₃ , the diode Q ₄ and the resistor R ₃ constitute a current sink circuit.

Next, the operation of the conventional switching circuit with leakage current compensation circuit having the above configuration will be explained.

First, when a leakage current I _CEO occurs when the switching lateral transistor _Q1 is cut off, this leakage current does not become the base current of the output transistor _Q2 , but is absorbed by the transistor _Q3 . Further, when a signal is input to the input terminal IN, a signal current that is sufficiently larger than the leakage current of the switching lateral transistor Q ₁ when cut off flows to the collector of the switching lateral transistor Q ₁ . A certain amount of the current is drawn into the collector current of the transistor _Q3 , but a current that is sufficiently larger than this collector current becomes the base current of the output transistor _Q2 , and the output transistor _Q2 becomes conductive. Therefore, a signal output can be taken out from the output terminal OUT.

However, in the conventional switching circuit with a leakage current compensation circuit, the sink current of the transistor _Q3 is required to match the absolute amount of the leakage current _ICEO at the time of interruption of the horizontal transistor _Q1 for _switching ; Considering that Q changes due to changes in temperature and that there are large variations during manufacturing, it becomes necessary to set the sink current setting value of transistor Q ₃ to a large value.
Operation at low signal levels is possible, and the leakage current I _CEO of the switching lateral transistor Q ₁ when cut off and the sink current I ₃ of the transistor Q ₃ are reduced.
Since they vary independently, it is possible to completely compensate for the cut-off leakage current of the switching lateral transistor _Q1 . Moreover, when this switching lateral transistor is integrated into a semiconductor integrated circuit, the leakage current at the time of cut-off is much larger than that of other individual component transistors,
Or, when using a horizontal transistor (generally a PNP transistor) in the first stage, which is larger than a vertical transistor in a semiconductor integrated circuit, to perform a switching operation, it becomes unnecessary, especially when the operating signal level is low or when operating at high temperatures. There were drawbacks such as the switching lateral transistor becoming conductive despite the signal.

Therefore, the purpose of the present invention is to focus on the fact that transistors with the same structure (such as the same lateral transistor) on the same chip of a semiconductor integrated circuit have similar leakage current generation modes during manufacturing and have almost the same leakage current characteristics. By using a leakage compensation lateral transistor with the same structure as the switching lateral transistor, the leakage current can be completely compensated by taking advantage of manufacturing variations and temperature characteristics that change in the same mode. A switching circuit with a compensation circuit is provided.

In order to achieve such an objective, this invention
an N-type (N-type) semiconductor substrate, an N-type (P-type) second semiconductor layer crystal-grown on the semiconductor substrate,
A P-type (N-type) third semiconductor layer formed within this second semiconductor layer, and a P-type (N-type) third semiconductor layer formed within the second semiconductor layer with this third semiconductor layer as a boundary, which act as an emitter, collector, and base, respectively. N type) fourth semiconductor layer, P type (N type) fifth semiconductor layer, and N ⁺
A plurality of lateral transistors each having a P type (P ⁺ type) sixth semiconductor layer are formed, and P type (N type ), a seventh semiconductor layer of N+ type (P+ type), an eighth semiconductor layer of N ⁺ type (P ⁺ type), and an N ⁺ type (P ⁺ type) serving as an emitter in the fourth semiconductor layer.
A vertical transistor is formed from a ninth semiconductor layer of type (type), the first horizontal transistor is used as a switching transistor that performs switching by application of an input signal, and the second horizontal transistor is used as an open-base leakage compensation transistor. This will be described in detail below using examples.

FIG. 3 is a sectional view of a semiconductor integrated circuit structure for explaining a switching circuit with a leakage current compensation circuit according to the present invention. In the figure, 1 is a normal P-type semiconductor substrate, 2 is on this semiconductor substrate 1,
A second semiconductor layer in which a crystal of a conductivity type opposite to that of the substrate (n type) is grown; 3 is a third semiconductor layer of the same type as the semiconductor substrate 1, which is diffused to provide electrical insulation between elements; 4 and 5 are A fourth semiconductor layer and a fifth semiconductor layer, 6 and 7, formed on the second semiconductor layer 2 and having a conductivity type opposite to that of the semiconductor layer 2 (p type), 6 and 7, are formed in the second semiconductor layer 2 and the fourth semiconductor layer, respectively. The sixth semiconductor layer and the seventh semiconductor layer have the same conductivity type as the second semiconductor layer 2 formed in the semiconductor layer 4. Then, a surface protection film is formed on the top surfaces of these semiconductors to protect the top surfaces of the semiconductors, and then electrodes are formed, and
A predetermined electronic circuit is formed using aluminum connections, but
A plurality of lateral transistors of the same type are formed on the same chip. One of them is used as a lateral transistor for switching, and the other one is used as a lateral transistor for leakage compensation. The leakage compensation lateral transistor has an open base and is connected in series or in parallel between the base and emitter of the switching lateral transistor.

Note that a lateral transistor is formed using the fourth semiconductor layer 4 as an emitter, the fifth semiconductor layer 5 as a collector, and the sixth semiconductor layer 6 as a base. A vertical transistor is formed using the semiconductor layer 7 as an emitter.

In this way, the switching lateral transistor and the leakage compensation lateral transistor are formed on the same chip, and the leakage compensation lateral transistor is used as an open base and is connected in series between the base and emitter of the switching lateral transistor. As a result, the leakage current I _CEO of the leakage compensating lateral transistor when cut off can be used as the base-emitter bias current of the switching lateral transistor. In this way, when the manufacturing leakage current value I _CEO of a switching lateral transistor and a leakage compensation lateral transistor manufactured at the same time on the same semiconductor substrate under the same manufacturing conditions is the same, the actual leakage current that occurs in the collector of the switching lateral transistor is Since the leakage current is bypassed by the leakage compensation lateral transistor, it becomes smaller than the leakage current of the leakage compensation lateral transistor, and the rate of malfunction due to the leakage current of the switching lateral transistor when there is no signal is greatly reduced. In general, the leakage current between the collector and emitter of a lateral transistor is smaller in the base-emitter bias state I _CER than in the base-emitter non-bias state _I It is possible to reduce the absolute amount of leakage current between the collector and emitter.

Additionally, in general, when fabricated into a semiconductor integrated circuit, 2
Characteristics of lateral transistors can be obtained that have good duality with respect to inherent parameters such as withstand voltage and hje, and the leakage current I _CEO when lateral transistors are cut off can be improved by placing them in adjacent positions on the same chip. You get something of duality.

FIG. 4 is a circuit diagram showing an embodiment of a switching circuit with a leakage current compensation circuit according to the present invention. In the figure, Q ₅ is an open-base type lateral transistor for leakage current compensation, R ₄ and R ₅
are horizontal transistors for switching Q ₁
and a resistor for voltage conversion of the collector current of the output transistor _Q2 , _R6 is a resistor connected between the base and emitter of the switching horizontal transistor _Q1 , and is also connected in series with the leakage current compensation horizontal transistor _{Q5, and COM is a resistor connected in series to the leakage current compensation horizontal transistor Q5} . This is a comparator that differentially outputs the collector current of the switching lateral transistor _Q1 and the collector current of the leakage current compensation lateral transistor _Q5 .

Next, the operation of the switching circuit with leakage current compensation circuit according to the above configuration will be explained.

First, if the inherent leakage currents of the switching lateral transistor Q ₁ and the leakage current compensation lateral transistor Q ₅ (both when their bases are open) at cut-off are approximately the same amount, then the leakage current I of the leakage current compensation lateral transistor Q ₅ is approximately the same amount. When _CEO5 flows through the resistor _R6 , a voltage is generated across the resistor _R6 , and this voltage biases the switching lateral transistor _Q1 to remain non-conductive, and shallowly biases the emitter to the base. Therefore, the leakage current I _CER1 of the switching lateral transistor Q ₁ when there is no signal is _smaller than I _CEO when it is open base (I _CEO5 > I _CER1 ).
The voltage across R ₅ will be less than the voltage across resistor R ₄ , and the output of comparator COM will be a "low" voltage. Therefore, output transistor _Q2 does not conduct. This state remains true even if the inherent leakage currents of the switching lateral transistor Q ₁ and the leakage compensation lateral transistor Q ₅ increase significantly, or even if the cutoff leakage current increases due to temperature changes.
The leakage currents of both the switching lateral transistor Q ₁ and the leakage compensation lateral transistor Q ₅ increase, and the condition of I _CER1 < I _CEO5 can be maintained due to the bias, so the switching lateral transistor Q ₁ and the leakage compensation lateral transistor Q ₅
It has almost no effect on the absolute amount of leakage.

On the other hand, in the signal mode, the input signal is input to the base of the switching horizontal transistor _Q1 , so
The output of the leakage compensation horizontal transistor _Q5 , that is, the voltage drop across the resistor _R4 , does not change, whereas the output of the switching horizontal transistor _Q1 , that is, the voltage drop across the resistor _R5 , changes depending on the magnitude of the signal input. In order to increase or decrease, the output of the comparator COM is in a high signal state and makes the output transistor _Q2 conductive.

In the above, the leakage current of the lateral transistor for leakage compensation _Q5 is used as the bias between the base and emitter of the lateral transistor for switching, and the leakage current at cut-off when the lateral transistor for leakage compensation is open base, I _CBO , and the emitter of the lateral transistor for switching are calculated.・Although the method of comparing the leakage current I _CER during base-to-base biasing has been explained, FIG. 5 shows a method of comparing the leakage current I _CBO at the time of cut-off of the leakage compensation lateral transistor Q ₅ and the switching lateral transistor Q 5 . In other words, an open-base leakage compensation lateral transistor Q ₅ (I _CBO operation), which has the largest leakage current in the same manufacturing process, is connected in parallel with the switching lateral transistor Q ₁ , and the differential output of their collector outputs is This differential output controls the output transistor _Q2 .

FIG. 5 is a circuit diagram showing another embodiment of the switching circuit with leakage current compensation circuit according to the present invention. The switching lateral transistor Q ₁ and the leakage compensation lateral transistor Q ₅ have a common emitter.
They are connected in parallel, and the input signal is input to the base of the switching horizontal transistor _Q1 . Further, the base of the leakage compensation lateral transistor _Q5 is open.

Next, the operation of the switching circuit with leakage current compensation circuit according to the above configuration will be explained. first,
Horizontal transistor for switching when there is no signal
Since both Q ₁ and the leakage compensation lateral transistor Q ₅ have open bases, the leakage currents I _CEO1 and I _CEO5 at the time of interruption are approximately the same. Therefore, the voltage drop across the terminals of resistors R ₄ and R ₅ will be the same, so the output of the comparator COM will be insignificant. Therefore, the leakage currents at cut-off I _CEO1 and I _CEO5
Since there is a margin for the operation against variations in , if the set values of resistors R ₄ and R ₅ are set to nR ₅ = R ₄ , leakage current can be compensated for I _CEO1 up to n times I _CEO5 .

In addition, since the switching lateral transistor Q ₁ and the leakage compensation lateral transistor Q ₅ have the same structure on the same semiconductor substrate, the leakage currents I _CEO1 and I _CEO5 at cut-off are the same despite manufacturing variations and temperature changes. Since they both increase and decrease according to the trend, when there is no signal, the leakage current causes the output transistor to
_Q2 never malfunctions.

Also, in the signal mode, the input signal is input to the base of the switching horizontal transistor _Q1 , so
Compared to the constant voltage drop across resistor R ₄ , resistor
The voltage across R ₅ increases with signal application, and the comparator
The output of COM makes output transistor _Q2 conductive.

In this way, a switching output is not generated simply by leakage from the switching lateral transistor _Q1 . Since it operates only when a leakage current greater than the leakage current of the leakage compensation horizontal transistor _Q5 occurs as a leak in the switching horizontal transistor _Q1 , it depends on the magnitude of the absolute value of the leakage current I _CBO of each transistor. In this case, no switching output occurs, so malfunctions caused by leakage current can be significantly improved.

As described above in detail, according to the switching circuit with leakage current compensation circuit according to the present invention, there is no need to control the absolute amount of leakage current in the manufacturing of semiconductor integrated circuits, and the relative amount of leakage amount can be controlled. Since it is determined whether or not a malfunction will occur based on only one test, it is not only easier to manufacture, but also the yield can be significantly improved. In addition, low-current operation circuits that require low leakage current when there is no signal, highly reliable labor-saving equipment, gas appliances, and home appliances that require stable operation without malfunction over a wide operating temperature range. It has an effect that can be widely used.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional switching circuit using horizontal transistors, Fig. 2 is a circuit diagram showing a conventional switching circuit with a leakage current compensation circuit, and Fig. 3 is a circuit diagram showing a switching circuit with a leakage current compensation circuit according to the present invention. A sectional view of a semiconductor integrated circuit structure for explaining the circuit, FIG. 4 is a circuit diagram showing an embodiment of a switching circuit with a leak current compensation circuit according to the present invention, and FIG. 5 is a circuit diagram showing an embodiment of the switching circuit with a leak current compensation circuit according to the present invention. FIG. 7 is a circuit diagram showing another embodiment of the switching circuit with the switch. Q ₁ ... Horizontal transistor for switching, Q ₂
...Output transistor, IN...Input terminal, OUT
...output terminal, _R1 ...resistance, _R2 ...load resistance,
Q ₃ ... Transistor, Q ₄ ... Diode, R ₃ ...
...Resistor, 1... Semiconductor substrate, 2... Second semiconductor layer, 3... Third semiconductor layer, 4... Fourth semiconductor layer,
5...Fifth semiconductor layer, 6...Sixth semiconductor layer, 7...
...Seventh semiconductor layer, Q ₅ ... Horizontal transistor for leakage current compensation, R ₄ , R ₅ and R ₆ ... Resistor, COM
...Comparator. Note that the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A P-type (N-type) semiconductor substrate, an N-type (P-type) second semiconductor layer crystal-grown on this semiconductor substrate, and a P-type (P-type) semiconductor layer formed in this second semiconductor layer. Type (N
A P-type (N-type) fourth semiconductor layer, a P-type (N-type) fourth semiconductor layer that serves as an emitter, a collector, and a base, respectively, are located within the second semiconductor layer with this third semiconductor layer as a boundary. Forming a plurality of lateral transistors each including a fifth semiconductor layer of N ⁺ type (P + type) and a sixth semiconductor layer of N + type (P ⁺ type), and in the second semiconductor layer with the third semiconductor layer as a border, P type (N
A seventh semiconductor layer of N+ type (P+ type), an eighth semiconductor layer of N ⁺ type (P ⁺ type), and an emitter in the seventh semiconductor layer.
A vertical transistor is formed from an N ⁺ type (P ⁺ type) ninth semiconductor layer, the first horizontal transistor is a switching transistor that performs switching by application of an input signal, and the second vertical transistor is an open base transistor. A switching circuit with a leakage current compensation circuit characterized in that it is used as a leakage compensation transistor. 2. A patent claim characterized in that a switching transistor is connected in series between the base and emitter of a leakage compensation transistor, and the subtraction output between the collector output of the switching transistor and the collector output of the leakage compensation transistor is used as the switching output. A switching circuit with a leakage current compensation circuit according to item 1. 3. A switching device with a leak current compensation circuit according to claim 1, characterized in that a leak compensation transistor and a switching transistor are connected in parallel, and the differential output of the collector output of each transistor is used as a switching output. circuit.