JPS628966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor integrated circuit device, particularly a first transistor having a base coupled to an input terminal, such as a transistor constituting a differential amplifier circuit, and a collector connected to the emitter of this transistor. Second
The present invention relates to a semiconductor integrated circuit device having a transistor.

The differential amplifier circuit includes two transistors whose emitters are connected to each other, and a current source transistor whose collector is connected to the emitter connection point. Differential amplifier circuits are widely used as a means of extracting a large output signal from a small input signal voltage, but when this is implemented as a semiconductor integrated circuit, the bases of two differentially connected transistors receive the input signal. For this purpose, it is connected to an external terminal of the integrated circuit provided as an input terminal. For this reason,
Differentially connected transistors may be destroyed by static electricity generated during the handling of integrated circuits, such as during testing, mounting and assembly of devices, and the like.

An object of the present invention is to provide a semiconductor integrated circuit device in which a transistor whose base is connected to an input terminal is protected from destruction due to static electricity.

In the present invention, a resistor for preventing electrostatic damage is connected to the emitter of a first transistor whose base is connected to an input terminal, and to the emitter of a second transistor whose collector is connected to this emitter.
It is characterized in that it is provided between the collector of the transistor.

Preferably, the first transistor constitutes one of a pair of differentially connected transistors, and the second transistor constitutes a constant current source transistor. Now, when a discharge path due to static electricity occurs between the input terminal as an external terminal provided in an integrated circuit device and the lowest potential terminal, the characteristic of the device structure when integrated circuit is that the lowest potential terminal → the second transistor A current flows through the path from the collector of the transistor to the electrostatic damage prevention resistor to the emitter of the first transistor to the base of the first transistor to the input terminal, but the resistor of the present invention limits this current and prevents damage to the first transistor. It can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an equivalent circuit diagram showing an embodiment of the present invention, and is an example applied to a differential amplifier circuit. Transition〓〓〓〓
The emitters of stars 5 and 6 are commonly connected to form a differential amplifier circuit, and their bases are connected to input terminals 1 and 2 (which are led out to external terminals of the integrated circuit) through resistors 3 and 4. connected). Their collectors are connected to a positive power supply terminal 11 via load resistors 9 and 10, and outputs 7 and 8 are taken out. Transistor 13 is a constant current source transistor of a differential circuit including transistors 5 and 6, and resistors 14 and 18 and diode 17 constitute a constant current source. The base of the transistor 13 is the bias end 16, and its emitter is the resistor 1
4 to the lowest potential terminal 15.

A resistor 19 for electrostatic damage protection according to the present invention is provided between the collector of the transistor 13 and the common connection point of the emitters of the transistors 5 and 6.

The circuit shown in FIG. 1 is formed on the same semiconductor substrate to constitute an integrated circuit device. Therefore, due to the characteristics of the device structure in integrated circuits, a discharge path due to static electricity is connected to the input terminal 1 or 2 and the terminal. 15
, collector of transistor 13 → resistor 19 → emitter of transistor 5 or 6 →
Current flows through the path of the base → resistor 3 or 4 → terminal 1 or 2. Therefore, overcurrent due to static electricity is limited by the resistor 19, and the transistor 5, which has a low breakdown voltage,
Otherwise, destruction of the base-emitter junction in No. 6 is prevented. Further, since the current flowing through the resistor 19 and the current flowing through the transistor 13 are the same, there is no problem with the differential amplification operation.

Note that the resistors 3 and 4 shown in FIG. 1 attenuate the input signals supplied from the input terminals 1 and 2,
Generating an offset voltage due to variations in the current amplification factors of the transistors 5 and 6 and variations in the resistors 3 and 4 further enhances the electrostatic damage prevention effect.
These are provided to protect against discharge between terminals 1 and 2. The resistance values of these resistors 3 and 4 are set to a small value of 100 to 300Ω. The presence of resistor 19 according to the present invention does not cause attenuation of the input signal or the generation of offset voltages.

As described above, according to the present invention, a highly reliable semiconductor integrated circuit that can protect against electrostatic ring breakage with a simple configuration is provided.

[Brief explanation of the drawing]

FIG. 1 is an equivalent circuit diagram showing one embodiment of the present invention. 1, 2... Input terminal, 3, 4, 19... Protection resistor, 5, 6, 13... Transistor, 7, 8...
Output, 9, 10, 14, 18...Resistance, 11...
Power supply terminal, 15...lowest potential terminal, 16...bias terminal, 17...diode. 〓〓〓〓

Claims (1)

[Claims] 1. A first transistor whose base is connected to an input terminal derived as an external terminal of an integrated circuit device without a PN junction and a second transistor whose collector is connected to the emitter of this first transistor are the same. In a semiconductor integrated circuit device configured on a semiconductor substrate, a resistor for preventing electrostatic damage of the first transistor is provided between an emitter of the first transistor and a collector of the second transistor. A semiconductor integrated circuit device characterized by: