JPS63304658A - Semiconductor circuit - Google Patents

Abstract

PURPOSE:To prevent the rise of a substrate potential caused by ionized current, by providing a substrate bias generating circuit which operates only when it is necessary to increase the capability of the substrate bias. CONSTITUTION:Between voltages VDD, VSS, two MOS transistors Q1, Q2 are connected in series, and a terminal 3 is formed, which is connected to a substrate bias generating circuit 4. To gate electrodes 1, 2 of the MOS transistors Q1, Q2, driving signals are input with a differential system, and an output signal is output to an output terminal 3. By driving the subsrtate bias generating circuit 4 with this output signal, the substrate bias generating circuit 4 operates to increase the capability of the substrate bias, only when the output signal is output to the output terminal 3. The rise of the substrate bias is restrained, thereby.

Description

[Detailed description of the invention] [Industrial application field] TECHNICAL FIELD The present invention relates to a circuit constituted by semiconductor elements.

[Conventional technology]

The output circuit of a normal semiconductor device is VD as shown in Figure 2.
Two MOS transistors Q, ,Q, between D and VssO
are connected in series, with 28 MOS transistors Q1. A drive signal is inputted to each gate electrode 1.2 of Q2 in a differential force type, and an output signal is outputted to an output terminal 3.

[Problem that the invention seeks to solve]

In addition, the technology of substrate bias generation circuits is widely known, and the substrate of an ordinary semiconductor circuit is normally reverse biased to -2 to -4V, but when an output signal is output to the output circuit, i.e. , transistor Q, or Q2 is turned on, holes are injected into the substrate by the turned-on transistor, causing an increase in the substrate potential and, in turn, causing an idle operation of the internal circuit. This phenomenon is
This is known as a defect caused by ionization current, and the magnitude of this ionization current is proportional to the current capability of the transistor. Therefore, this effect becomes significant in output circuits where the size of transistors is inevitably large due to the current capability required.

[Means for solving problems]

An object of the present invention is to provide an effective means for preventing an increase in substrate potential due to an ionization current generated when an output signal is output to an output terminal.

The present invention relates to a semiconductor device incorporating a substrate bias circuit, which includes an output circuit whose main component is two MOS transistors connected in series, and which is driven using an output signal from an output terminal of the output circuit. When the substrate potential rises due to the ionization current generated when it is output to the output terminal, the output signal drives the substrate bias circuit at the same time, increasing the capability of the substrate bias circuit and increasing the substrate potential. This is a semiconductor circuit characterized by suppressing the rise in .

- [Example] An embodiment of the present invention will be described based on FIG.

Two MOS) transistors Q between VDD and Vss.
Q, are connected in series to form an output terminal 3.

Further, the output terminal 3 is connected to a substrate bias generation circuit 4.

At this time, drive signals are input to the gate electrodes 1.2 of each of the MOS transistors Ql and Qz in a differential force type, and an output signal is output to the output terminal 3. This output signal drives the substrate bias generation circuit 4. In addition, the substrate bias generating circuit 4 operates only when an output signal is output to the output terminal 3 to increase the substrate bias capability, thereby suppressing an increase in the substrate bias.

Another embodiment of the invention is shown in FIG. This is an embodiment in which two MOS transistors Q3 and Q4 and a capacitor C are connected in series between the substrate and Vss as the substrate bias generating circuit 4 shown in FIG.

〔Effect of the invention〕

As already shown, the generation of ionization current, which is harmful to the operation of semiconductor devices, tends to occur when an output signal is output to the output terminal, leading to an increase in substrate bias.However, the present invention improves the ability of substrate bias. By providing a substrate bias generation circuit that operates only when an increase in substrate bias is necessary, an increase in substrate bias can be effectively suppressed.

So far, we have explained N-channel MO8) transistors, but also in the case of P-channel MOS transistors.
It is clear that the same applies.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing a conventional output circuit, and FIG. 3 is a circuit diagram showing an application example of the present invention. Q1-Q4...-MOS transistor, 1-3.
. . . Node, 4 . . . Substrate bias generation circuit, 5 . . . Substrate, C .

Claims (1)

[Claims] A semiconductor device incorporating a substrate bias circuit, which is an output circuit whose main component is two MOS transistors connected in series, and whose output signal is used to drive the substrate bias circuit.