JPH03208369A - Semiconductor input circuit - Google Patents

Abstract

PURPOSE:To avoid the erroneous operation due to the noise potential of an input amplification circuit by a method wherein a circuit producing a potential difference by an outer signal is made at the front state of the input amplification circuit inputting the outer signal while an inner grounding wire is connected to the line between said potential difference producing circuit and the input of the input amplification circuit through a transmission circuit. CONSTITUTION:An outer signal is transmitted to an integrated circuit 2 so as to be inputted in an input amplification circuit 3 through a resistor 8 thus producing a potential difference across the resistor 8. An inner grounding wire 4 is connected to the input of the input amplification circuit 3 through a capacitor element (transmission circuit) 7 so that the noise potential generated between the inner grounding wire 4 and an outer grounding wire 5 may be transmitted to the input of the inner amplification circuit 3 by the capacitor element 7. Furthermore, since the outer signal being inputted in the input amplification circuit 3 produces a potential difference across the potential difference producing circuit 8, the outer signal is inputted in the input amplification circuit 3 while being superposed with noise potential transmitted through the transmission circuit 7 thereby canceling the effect of the noise potential. Through these procedures, the erroneous operation due to the noise potential of the input amplification circuit 3 can be avoided without fail.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor input circuit used in an input stage of an external signal in a semiconductor circuit such as an integrated circuit.

(Prior Art) FIG. 3 shows a conventional semiconductor input circuit used in an external signal input stage of a semiconductor integrated circuit.

The signal generated by the external signal generation circuit 1 is transmitted to the integrated circuit 2.
The signal is input to an internal input amplifier circuit 3.

This input amplifier circuit 3 has an internal grounding line 4 inside the integrated circuit 2.
The input signal is judged based on the . The signal amplified by this input amplifier circuit 3 is further sent to a semiconductor circuit (not shown) inside the integrated circuit 2 and is processed as appropriate.

Further, the resistance actance 6 shown between the internal grounding line 4 and the external grounding line 5 outside the integrated circuit 2 is representative of the resistance component of the impedance of the internal grounding line 4.

(Problems to be Solved by the Invention) Here, if the integrated circuit 2 operates at high speed,
Since a large current flows through the internal ground line 4 inside the integrated circuit 2, a relatively large potential difference is generated between it and the external ground line 5 due to the reactance 6. However, the signal from the signal generation circuit 1 is based on the potential of the external ground line 5, and the judgment of the input amplifier circuit 3 is based on the potential of the internal ground line 4 as described above. If there is a potential difference between the line 4 and the line 4, this becomes a noise voltage and causes the input amplifier circuit 3 to make a wrong decision.

Therefore, in order to reduce such noise voltage,
The current flowing through the internal grounding wire 4 may be limited. but,
Limiting the current in this way comes at the expense of high speed operation of the circuit.

In addition, the impedance of the internal grounding wire 4 (reactance 6
) can also reduce the noise voltage. However, in order to reduce the impedance of the internal grounding line 4, it is necessary to increase the area of this internal grounding line 4, which increases the physical size of the integrated circuit 2. This would be contrary to the request. Furthermore, even if the impedance of the internal ground line 4 can be reduced, if the impedance of the external ground line 5 is high, the essential effect of reducing noise voltage cannot be expected.

For this reason, in conventional semiconductor circuits such as the integrated circuit 2 that operates particularly at high speed and the integrated circuit 2 used with the high impedance external grounding line 5, the input amplifier circuit 3 of the semiconductor input circuit may malfunction due to the noise voltage. There is a problem in that it is not possible to completely prevent this from occurring.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a semiconductor input circuit that can reliably prevent malfunctions of the input amplifier circuit due to noise voltage.

(Means for Solving the Problems) A semiconductor input circuit of the present invention includes a potential difference generation circuit that generates a potential difference based on an external signal, which is provided at a stage before an input amplifier circuit that inputs an external signal. The input of the input amplifier circuit is connected to the internal ground line via a transmission circuit for transmitting the potential of the internal ground line, thereby achieving the above object.

(effect) FIG. 1 shows the configuration of a semiconductor input circuit according to the present invention.

It should be noted that the same numbers are added to components having the same functions as those of the conventional semiconductor input circuit shown in FIG.

External signals are output signals from various elements and circuits, and the signal generation circuit 1 represents the source of this external signal in the figure. This external signal is generated with the potential of the 7F section grounding line 5 as a reference.

Further, an internal ground line 4 of the semiconductor circuit 2 is connected to this external ground line 5. However, since this internal grounding line 4 has a relatively large impedance, the reactance component is shown as a representative reactance 6 in the figure.

Also in the semiconductor circuit 2, the operating current flows through the reactance 6, so that the internal grounding line 4 and the external grounding line 5 are connected to each other.
A noise voltage is generated between the

Therefore, if the potential of the internal ground line 4 is used as the reference for the external signal, the level of the external signal appears to be relatively lowered due to this noise voltage.

However, in the present invention, this noise voltage is transmitted to the input of the input amplifier circuit 3 by the transmission circuit 7. For this transmission circuit 7, a capacitive element or the like is used, for example. Furthermore, when the external signal is input to the input amplifier circuit 3, a potential difference is generated between both ends of the potential difference generating circuit 8.

This potential difference generating circuit 8 uses, for example, a resistance element. Therefore, the external signal is input to the input amplifier circuit 3 with the noise voltage transmitted via the transmission circuit 7 superimposed thereon.

Therefore, the input amplifier circuit 3 can judge the external signal by canceling out the influence of the noise voltage, so that malfunctions caused by the noise voltage can be reliably prevented.

As a result, if the semiconductor input circuit of the present invention is used, there is no need to limit the operating current of the semiconductor circuit or forcefully reduce the impedance of the internal grounding line, so it is not necessary to limit the operating current of the semiconductor circuit or forcefully reduce the impedance of the internal grounding line. Obstacles can be removed. Furthermore, it is possible to provide a semiconductor circuit that is guaranteed to operate reliably even when the external ground line has high impedance.

(Example) The invention will be explained below by way of examples.

FIG. 2 is a block diagram showing the configuration of a semiconductor input circuit according to an embodiment of the present invention. Note that the same numbers are added to components having the same functions as those of the semiconductor input circuit shown in FIG.

The signal generating circuit 1 generates an external signal using an external ground line 5 as a reference. The external signal generated by the signal generating circuit 1 is sent inside the integrated circuit 2 and is input to the input amplifier circuit 3 via the resistor 8. The resistor 8 is an element for generating a potential difference between both ends using this external signal.

The input amplifier circuit 3 judges the input signal based on the internal ground line 4 inside the integrated circuit 2, and the signal amplified by the input amplifier circuit 3 is further transmitted to a semiconductor circuit (not shown) inside the integrated circuit 2. will be sent to and processed accordingly.

Further, the internal ground line 4 is connected to the input of the input amplifier circuit 3 via a capacitive element 7.

Capacitive element 7 is an element for transmitting the potential of internal ground line 4 to the input amplifier circuit 3 .

Here, an internal grounding wire 4 and an external grounding wire 5 outside the integrated circuit 2
The normal actance 6 between the internal grounding line 4 and the internal ground line 4 is representative of the positive actance component of the impedance of the internal grounding line 4.

Also in the above integrated circuit 2, the operating current is reactance 6
As a result, a noise voltage is generated between the internal ground line 4 and the external ground line 5. Therefore, if only the external signal is input to the input amplifier circuit 3, the level of the external signal will be relatively lowered by this noise voltage, and the input amplifier circuit 3 may malfunction.

However, in this embodiment, this noise voltage is transmitted to the input of the input amplifier circuit 3 by the capacitive element 7. Furthermore, when the external signal is input to the input amplifier circuit 3, a potential difference is generated between both ends of the potential difference generating circuit 8. Therefore, the external signal is superimposed with the noise voltage transmitted via the transmission circuit 7 and input to the input amplifier circuit 3, so that the influence of the noise voltage is canceled out inside the input amplifier circuit 3. be done.

Therefore, the input amplifier circuit 3 can judge external signals without being affected by this noise voltage, and can reliably prevent malfunctions. Furthermore, as a result, there is no need to limit the operating current of the integrated circuit 2 or to forcefully reduce the impedance of the internal grounding line 4, so that it is possible to increase the speed of circuit operation and achieve high-density packaging. Furthermore, reliable operation is guaranteed even when the external grounding line 5 has high impedance.

(Effects of the Invention) As is clear from the above description, the semiconductor input circuit of the present invention can be used without sacrificing high-speed operation or high-density packaging of the semiconductor circuit, and even when the impedance of the external ground line is high. , it is possible to reliably prevent malfunctions of the input amplifier circuit due to noise voltage.

4. Figure 1 is a block diagram showing the configuration of a semiconductor input circuit according to the present invention, Figure 2 is a block diagram showing the configuration of a semiconductor input circuit according to an embodiment of the present invention, and Figure 3 is a block diagram showing the configuration of a semiconductor input circuit according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a semiconductor input circuit.

3... Input amplifier circuit, 4... Internal grounding wire, 5...
External grounding wire, 7... Capacitive element (transmission circuit), 8...
Resistor (potential difference generation circuit).

that's all

Claims (1)

[Claims] 1. A potential difference generation circuit that generates a potential difference based on the external signal is provided before the input amplifier circuit that inputs an external signal, and the internal ground line is connected between the potential difference generation circuit and the input of the input amplifier circuit. A semiconductor input circuit connected to the internal ground line via a transmission circuit for transmitting a potential.