JP2528809B2 - Semiconductor integrated circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit having an internal voltage generating circuit suitable for preventing oscillation (ringing) of a sense output signal voltage or the like in a sense circuit of a semiconductor memory, for example. .

[Background of the Invention]

A circuit shown in FIG. 1 is known as a sense circuit of a conventional memory LSI. In FIG. 1, 15 is a word line, 16 digit lines, 17 is a memory cell, 18 is a current source for holding information,
Reference numeral 19 is a current source for clamping a digit line, and 20 is a current source for reading. A reference voltage is applied to the base of the transistor 10 in which the emitter is connected to each digit line, the collectors of these transistors are connected in common, and are connected to the emitters of the transistors 1 and 2, respectively, to form a wired OR connection. ing. Reference numerals 6, 7, 8 and 9 are transistors for selecting a pair of digit lines. According to this circuit, the read current flows through either the transistor 1 or the transistor 2 depending on the information state of the selected memory cell. Accordingly, a potential difference is generated on the sense output signal lines 3 and 4, and the memory information is output via the differential amplifier 21. Conventionally, in this circuit, the bases of the transistors 1 and 2 are commonly driven by one internal voltage source.

Next, the drawbacks of this method will be described. The digit line selection signal V _Y1 switches from high potential (High) to low potential (Low),
When V _Y2 is switched from Low to High, the read current flowing from the transistors 6 and 7 is cut off, and the read current flows from the transistors 8 and 9. At this time, it does not matter if the read currents flowing through the transistors 6 and 7 and the transistors 8 and 9 are switched as shown by the broken line in FIG. 3, but when V _Y2 is switched from Low to High, In order to charge the stray capacitance Cs of the emitter, a current with an overshoot as shown by the solid line in FIG. 3 is generated, and thereafter, ringing occurs like the ringing phenomenon of the emitter follower. This tendency tends to be more pronounced as the junction capacitance, base resistance, and emitter resistance of the transistor become smaller. Therefore, the more the device is miniaturized for high speed and high integration, the more strongly it appears. As described above, the stored information in the memory cell is sensed by applying a read current to either the transistor 1 or the transistor 2 and causing a potential difference in the sense output signal. When a read current with large oscillation flows through the transistor 1 through the transistor 8 and the transistor 10, the voltage of the sense output signal line 3 which is the collector voltage of the transistor 1 oscillates. At this time, due to the oscillation of the current flowing through the transistor 1, the voltage of the internal voltage source 5, which is the base voltage of the transistor 1, oscillates, and the base voltage of the commonly connected transistors 2 also oscillates. Therefore, the current of the transistor 2 oscillates, and as shown by the solid line in FIG. 4, the voltage of the sense output signal line 4, which is the collector voltage of the transistor 2, oscillates.
That is, in the conventional circuit, the bases of the transistors 1 and 2 are set to 1
Since the two internal voltage sources 5 are used for driving, the vibration of the current flowing through the transistor 1 induces the vibration of the current flowing through the transistor 2.

The problem of the conventional circuit has been described above with respect to the memory sense circuit. However, the above problem is not limited to the memory sense circuit, and the same applies to semiconductor integrated circuits having the same circuit format.

[Object of the Invention]

An object of the present invention is to provide a semiconductor integrated circuit which detects a current of a plurality of transistors whose base voltage is commonly driven by one internal voltage source, by detecting a potential change in a load connected to a collector of each transistor. An object of the present invention is to provide a semiconductor integrated circuit which is more stable in operation by preventing the vibration of the current flowing in one transistor from inducing the vibration in the current flowing in the other transistor.

[Outline of Invention]

The cause of the linking that occurs in the conventional circuit is that one internal voltage source drives the bases of multiple transistors. Therefore, the oscillation of the current flowing in one transistor causes the voltage of the internal voltage source to oscillate, and It should be to oscillate the current of the other transistor, which should not be done. Therefore, as a solution to this problem, the bases of the plurality of transistors may be driven by different internal voltage sources to prevent the induction of vibration.

Example of Invention

An example of application to a sense circuit of a memory will be described below as an embodiment of the present invention with reference to FIG.

The configurations of the transistors 1 and 2, the sense output signal lines 3 and 4, the differential amplifier, and the read current switching transistors 6 to 10 are all the same as those of the conventional circuit. Internal voltage sources 5 and 11 are separate internal voltage sources that are a feature of the present invention. The internal voltage source 5 is connected only to the base of the transistor 1, and the internal voltage source 11 is connected only to the base of the transistor 2. The internal voltage sources 5 and 11 are preferably voltage sources having the same characteristics in terms of circuit design.

Since the sensing method of this circuit is exactly the same as that of the conventional circuit, description thereof is omitted, and the effect of separating the internal voltage source, which is a feature of the present invention, will be described below.

According to the present embodiment, even if a large oscillation (ringing) current flows through the transistor 1 as shown by the solid line in FIG. 3 and the base voltage of the transistor 1 is oscillated, the bases of the transistors 1 and 2 are also oscillated. Is not connected as in the past, but is separated, so transistor 2
The base voltage of does not oscillate. Therefore, the transistor 2
Current does not oscillate, and the collector voltage of the transistor 2 does not oscillate as shown by the alternate long and short dash line in FIG. As described above, according to the present embodiment, there is an effect that the voltage oscillation (ringing) that occurs when the sense output signal switches from the low potential to the high potential does not occur.

〔The invention's effect〕

According to the present invention, it is possible to prevent voltage oscillation (ringing) that occurs when the sense output signal switches from the low potential to the high potential, which is effective in stabilizing the operation of the differential amplifier that receives the sense output signal.

The example applied to the sense circuit of the memory has been described above, but it goes without saying that the effects of the present invention can be expected even in a semiconductor integrated circuit having the same circuit type.

[Brief description of drawings]

FIG. 1 is a conventional sense circuit, FIG. 2 is a sense circuit showing an embodiment of the present invention, and FIGS. 3 and 4 are operation explanatory views for explaining problems of the conventional circuit and effects of the present invention. 5,11 …… Internal voltage generation circuit.

Claims (1)

(57) [Claims] 1. A plurality of memory cells, a pair of digit lines to which the plurality of memory cells are connected, a first transistor whose emitter electrode is connected to one of the pair of digit lines, and an emitter electrode thereof. A second transistor connected to the other of the pair of digit lines, a third resistor connected to the collector electrode of the first resistor, and an emitter electrode connected to the collector electrode of the first transistor. And a fourth transistor whose collector electrode is connected to a second resistor and whose emitter electrode is connected to the collector electrode of the second transistor, and which detects a potential change due to the first and second resistors. A differential amplifier, a first internal voltage source circuit that supplies a base potential to the third transistor, and a base to the fourth transistor. The semiconductor integrated circuit and having a second internal voltage supply circuit different from the first internal voltage supply circuit for supplying position.