JPS604620B2 - semiconductor inverter circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inverter circuit suitable for semiconductor integrated circuits, and particularly to a semiconductor inverter circuit with excellent low-level output temperature characteristics.

In general, inverter output circuits, even in the case of a so-called open collector, have a conduction bell, that is, a potential difference Vo between the collector and emitter (ground) of the output transistor when the output transistor is conductive, to a certain value (usually 0.4
~0.5V) or lower is necessary in order to use it as an output of general transistor transistor logic (TTL) or diode transistor logic (DTL).

Conventionally, one way to solve these factors is to diffuse gold throughout the integrated circuit, including the inverter output circuit.
When the output transistor was in operation, the base overdrive completely saturated the output. However, gold diffusion improves the controllability of other properties and properties during manufacturing.
It is known that there is some deterioration in rollability, and this is becoming more and more noticeable as the processes in integrated circuits become more sophisticated. Therefore, without this gold diffusion, and therefore without completely saturating the inverter,
Moreover, various methods for obtaining a predetermined continuity level VoL have been proposed.

Many of these fall within the concept shown in Figure 1. That is, the emitter of the output transistor Q is grounded, the base is connected to the connection point a of the resistors R, , R2, and the collector is connected to the emitter of the transistor Q2, from which the output terminal 1 is led out. The collector of the transistor Q2 is feedback-connected to the drive circuit 2, and the base is also connected to the drive terminal of the drive circuit 2. An input signal is supplied to the drive circuit 2 from an input terminal 3. The inverter output transistor Q, is driven by the drive circuit 2 to a conductive state through the resistor R2, but by appropriately selecting the ratio of the resistors R, , R2, the transistor Q2 performs feedback to the drive circuit, and the transistor The output level is clamped below a predetermined value so that Q is not completely saturated. The simplest circuit is shown in FIG.
be yourself. Therefore, the transistor Q2 operates as a diode with the collector connected to the base, and the transistor Q2 operates as a diode with the collector connected to the base.
, is about to reach saturation, the collector current of transistor Q2 increases. This is known as a base clamp. Specific examples in which the collector of transistor Q2 is connected in feedback to various other points in the drive circuit are shown in FIGS. 2B and 2C. In these, the part within the dotted line is the above-mentioned drive circuit 2.
These circuit configurations are simple and are often used, but they have the following drawbacks. That is, the clamped level of output terminal 1 is now VoL, the base-emitter potential of transistor Q is VBE, and the resistance values of resistors R, , R2 are R, .
R2, the potential at point a is VBEI, and the current value divided by the resistance value R of resistor R flows through resistor R2, and due to that current, the potential at point b is R3XVBE.
Therefore, the potential VOL of the output terminal 1 becomes the value obtained by subtracting the VBE2 of the transistor Q2 from the potential at point b. V skin: VBE
If it is 2, then VOL=Uke×V leg. Therefore V. L is V
BE, and has a negative temperature coefficient. Therefore, as the operating temperature of the circuit increases, V. There was a drawback that L decreased and saturation was apt to occur. The purpose of the present invention is to improve the conduction level V of this output transistor.

It is an object of the present invention to provide a semiconductor inverter circuit which eliminates the temperature coefficient of L, that is, makes it substantially zero so that it does not saturate over a wide operating temperature range, and is therefore suitable for high-speed operation. Another object of the present invention is to provide a semiconductor inverter circuit that is easy to manufacture by widening the tolerance range between a predetermined maximum standard value of VoL and a minimum limit value for preventing saturation, thereby increasing manufacturing margin. It is in.

In the present invention, a current source whose current changes with a positive temperature coefficient is connected to the base of the output transistor. Such a current source can be obtained as follows. That is, the forward potential drop VF (commonly referred to as VB8) of a diode or transistor has a negative temperature coefficient, but the absolute value of the coefficient strictly depends on the value of VF, and the larger VF is, the smaller it is. Therefore, two elements having VF (VB) are used so that they have different VFs at the same temperature.
That is, a series circuit of a transistor and a second resistor is provided in parallel between the base and emitter of the transistor after the drive signal is applied to the base from the drive circuit via the first resistor. Furthermore, a diode-operating element is connected between the base of this transistor and ground. A current corresponding to the current for controlling conduction/non-conduction of the output stage transistor is supplied to the element performing diode operation via the fourth resistor. According to this configuration, the current flowing through the first resistor that drives the base of the output stage transistor has a positive temperature coefficient, so that the output voltage VoL
temperature fluctuations can be prevented. In the conventional circuit (Fig. 1), VoL has a negative temperature coefficient because the current flowing through resistor R2 is equal to the current flowing through resistor R2, and therefore, it has a negative temperature coefficient depending on VB8 of transistor Q. Therefore, in the present invention, a current source with a current value having a positive temperature coefficient is newly connected in parallel with the resistor R, and the temperature coefficient of the total current flowing through the resistor R2 is set to zero, and V. The temperature coefficient of L is compensated. FIG. 3 is a conceptual diagram of the inverter circuit of the present invention, in which a current value 1 flowing through the resistor R has a negative temperature coefficient, whereas a current source 4 with a current value 12 is newly connected at point a. do.

This current source 4 is made to have a positive temperature coefficient. The current flowing through the resistor R2 is 1,112, and this value is constant regardless of temperature changes, and the potential at point b is constant, so the output level VoL has a temperature coefficient of 0. Of course, it is also possible to give an arbitrary temperature coefficient by changing the ratio of 1 and 12. However, what should be noted here is that the current source 4 cannot be configured completely independently of the inverter circuit. That is,
When the inverter circuit is non-conductive, the impedance seen from the current source 4 at point a is high, so unless the current source 4 is also made non-conductive, the current source 4 itself will become saturated. An embodiment showing a specific configuration of the current source 4 having a positive temperature coefficient is shown in FIG.

A point a is connected to a current source 4 including a series circuit of a transistor Q and a resistor R3, a diode D, and a series circuit of a resistor R4.
Ground through. In this way, the transistor Q3 and the diode D are used as the two elements with different VFs. In this configuration, the VF of diode D is greater than the VBE of transistor Q. Therefore, as the temperature rises, the rate at which VF of diode D decreases is smaller than the rate at which transistor VB8 decreases, and the current flowing through resistor R3 has a positive temperature coefficient. That is, the Vp of the diode D is set to VFo, the VF of the transistor Q3 is set to VF3, and the gap energy potential difference of the semiconductor is set to VG (approximately 1
．． 2V), the temperature coefficients of VFo and VF3 are expressed approximately as below. △VF.

/△T=(VF.-Vc)/TTemperatureT is the absolute temperature (oK
)) △VF3/△T; (VF3-VG)/T Therefore, resistor R. , R3 respectively have currents 1,,1
Each temperature coefficient of 2 is △1, /△T=△(VF, /R, /△
T=(VF, -VG)/R, T/<0 △12/△T=△(VF, -VF.

) R3/ΔT=(VF, -VF.)/R3T>0.

Therefore, if the dimension of diode D and the resistance value of resistor R3 are appropriately selected, the negative temperature coefficient △1,/△T of 1 above can be canceled out by the positive temperature coefficient of 12,
Temperature coefficient △R2 (1,11
2)/ΔT can be made zero. transistor Q,
If VF of Q2 and Q2 are set to be approximately the same, the output low level will be equal to V2, so the temperature fluctuation of the output level will be zero, and the objective will be achieved. Furthermore, when transistor Q is non-conducting (
At this time, when the output terminal 1 becomes high level, the potential on the anode side of the diode D becomes low and the operation of the current source 4 is stopped. Furthermore, according to this embodiment, the constant current source 4 is composed of a transistor Q3, a diode D, and resistors R3 and R4, and the current value 12 of the constant current source 4 is determined by the transistor Q3.
, the VF of transistor Q3 (VF3
) and the VF (VFo) of the diode D.

Therefore, the potential drop of the resistor R2, that is, the temperature coefficient of the output low level, can be made zero regardless of the fluctuation of VF due to the output load current. The current of the diode ○ is supplied from point b through the resistor R4 so that almost no current flows when the output transistor Q is non-conductive. The current supply source of this diode D is not limited to point b as long as the current value is controlled according to the conduction of the output transistor as described above. FIG. 5 shows a case where the base potential of the drive transistor Q of the drive circuit 2 is used to supply current to the diode D.

The reason why transistor Q4 is interposed between point c and diode D is to prevent current from flowing through diode D because when transistor Q becomes non-conductive, transistor Q also becomes non-conductive. . In this circuit, the current in diode D is more stable than in the case where current is supplied to diode D from point b. D2 and D3 are for preventing saturation of the transistor Q5. The current source 4 in FIGS. 4 and 5 is a constant current source. According to the inverter circuit of the present invention, the temperature coefficient of the conduction bell of the output transistor can be made essentially zero, and processes such as gold diffusion and Schottky diodes are not required. It is suitable for various sense amplifiers and output circuits of semiconductor memories.

[Brief explanation of the drawing]

Fig. 1 is a connection diagram showing a conventional semiconductor inverter circuit, Fig. 2 is various connection diagrams of a conventional inverter circuit embodying a drive circuit, Fig. 3 is a conceptual diagram of the semiconductor inverter circuit of the present invention, and Fig. 4 is FIG. 5 is a circuit connection diagram showing a specific embodiment of the semiconductor inverter circuit of the present invention. FIG. 5 is a connection diagram showing another embodiment of the inverter circuit of the present invention. Q,: first transistor, Q2: second transistor, R
, : first resistor, R2: second resistor, 4: current source. / Figure 3 Figure 2 Viscount Kai's younger brother J Figure

Claims (1)

[Claims] 1. Take out the output from the series connection point of the first transistor and the second transistor connected to the drive circuit, and connect the input of the second transistor to the first resistor and the second resistor connected to the drive circuit. In the semiconductor inverter circuit driven by the potential of a series connection point of the second transistor, a series circuit of a third transistor and a third resistor is provided between the input terminal of the second transistor and a reference potential, and the third transistor An element that performs a diode operation is connected between the input terminal of the transistor and a reference potential, and a current whose current value is controlled according to on/off of the second transistor is supplied to the element that performs a diode operation. A semiconductor inverter circuit characterized by supplying power through a resistor.