JP2579517B2 - Reference voltage generation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] For example, regarding a reference voltage generation circuit suitable for use in an emitter-coupled logic circuit, there is a variation in drain current characteristics of transistors for dividing a power supply voltage. Also, the purpose is to reduce the reference voltage fluctuation so that the current-to-voltage characteristics of the series-connected transistors and the current-to-voltage characteristics of the series-connected transistors intersect in the current unsaturated region. A first transistor group and a second transistor group each having a selected number of transistors and interposed between a positive power supply line and a negative power supply line; and the positive power supply line and the negative power supply. A connection point between the first transistor group and the second transistor group for dividing a voltage between lines and extracting a reference voltage; The configuration is as follows.

[Industrial applications]

The present invention relates to a reference voltage generation circuit suitable for use in, for example, an emitter coupled logic (ECL) circuit.

[Conventional technology]

Generally, metal semiconductor field effect (MESFET)
transistor and high electron mobility transistor (high elec
GaA composed of tron mobility transistor (HEMT)
An s-based integrated circuit device is often used in combination with a silicon-based bipolar integrated circuit device.

Therefore, it is necessary to adjust the input / output level to the ECL level.
L) type is known, and it is said that resistance to variation in element characteristics is large.

By the way, for this SCFL type circuit, the reference voltage V
_REF (for example, -1.3 [V]) must be supplied, and in order to reliably operate the integrated circuit device, its reference voltage is required.
Of course, the stability of V _REF is important.

FIG. 4 is a main part circuit diagram for explaining a conventional example.

In the figure, R1 and R2 are resistors, _VSS is the negative power supply voltage, V
_REF indicates the output reference voltage.

This conventional example is a resistance division type reference voltage generation circuit, in which a power supply voltage is divided by resistors R1 and R2 selected to have a value suitable for obtaining a reference voltage V _REF of -1.3 [V]. The divided voltage is taken out as an output from a connection point between the resistors.

FIG. 5 is a main part circuit diagram for explaining another conventional example, and the same symbols as those used in FIG. 4 indicate the same parts or have the same meanings.

In the figure, T1 and T2 indicate depletion type field effect transistors.

In this conventional example, the sources and gates of the transistors T1 and T2 are short-circuited, so-called diode-connected, and the internal resistances of these diodes are used in the same manner as the resistors R1 and R2 shown in FIG. Things.

[Problems to be solved by the invention]

In the conventional example shown in FIG. 4, resistors R1 and R2 must be formed on a semiconductor chip with high accuracy, but this is often difficult in the manufacturing process of an integrated circuit device. To solve this problem, a conventional example shown in FIG. 5 has appeared, but the improved reference voltage generation circuit still has a drawback.

FIG. 6 is a diagram showing the drain voltage-drain current characteristics in the conventional example shown in FIG. 5, in which the horizontal axis represents the drain voltage and the vertical axis represents the drain current.
Note that the same symbols as those used in FIG. 5 represent the same parts or have the same meanings.

In the figure, t1 is I (current) -V of the transistor T1.
(Voltage) characteristic line, t2 is an IV characteristic line of the transistor T2,
t11 indicates an IV characteristic line when the transistor T1 is replaced with another transistor.

As can be seen from the figure, the reference voltage generating circuit uses a region where the currents of the transistors T1 and T2 are saturated and the slopes of the characteristic lines t1 and t2 are small, and the characteristic lines t1 and t2
Is extracted as a reference voltage V _REF .

For this reason, for example, when the transistor T1 is replaced with another transistor, and the drain current characteristic of the transistor is slightly different from that of the transistor T1, for example, assuming that the characteristic is indicated by the symbol t11 , The reference voltage V _REF varies greatly. This is not only true for transistor T1, but also for transistor T1.
Of course, this can happen with T2 as well.

An object of the present invention is to provide a reference voltage generating circuit having a configuration in which a reference voltage does not fluctuate even if there is variation in drain current characteristics of a transistor for dividing a power supply voltage.

[Means for solving the problem]

FIG. 1 is a main part circuit diagram showing a reference voltage generating circuit for explaining the principle of the present invention. The same symbols as those used in FIGS. 5 and 6 indicate the same parts or are the same. It has meaning.

In the figure, Q11, Q12 ... are transistors on the positive power line side, Q12, Q22 ... are transistors on the negative power line side, and A is a group consisting of transistors Q11, Q12 ... (First transistor group), B is a group consisting of transistors Q21 and Q22 (second transistor group)
Group) and N indicate connection points between group A and group B, respectively.

As is clear from the figure, from the connection point N, the reference voltage V _REF
Is output, and the number of transistors Q11 and the like included in the group A and the number of transistors Q21 and the like included in the group B are determined by the IV characteristic line of the group A and the IV characteristic line of the group B. And are able to intersect in the unsaturated region.

FIG. 2 is a diagram showing drain voltage versus drain current characteristics in the reference voltage generating circuit shown in FIG. 1, in which the horizontal axis represents drain voltage and the vertical axis represents drain current. Note that the same symbols as those used in FIGS. 1 and 6 represent the same parts or have the same meanings.

In the figure, a shows the IV characteristic line of the group A, and b shows the IV characteristic line of the group B.

As can be seen from the figure, the reference voltage generating circuit uses a region where the currents of the groups A and B are unsaturated and the slopes of the characteristic lines a and b are large. The voltage corresponding to the point where b intersects is taken out as the reference voltage _VREF .

From the above, transistors Q11, Q12 ...
Alternatively, it can be understood that the value of the reference voltage V _REF does not significantly change even if the drain current characteristics such as Q21, Q22,...

Therefore, in the reference voltage generating circuit of the present invention, the current-voltage characteristics (for example, I.sub.I) shown by the series-connected transistors (for example, transistors Q11, Q12...)
The current-voltage characteristics (for example, the IV characteristic line b) of the transistors (for example, the transistors Q21, Q22,...) Connected in series similarly to the -V characteristic line a) cross each other in the current non-saturation region. A first transistor group (for example, group A) and a second transistor group (for example, group B) having a selected number of transistors interposed between the positive power supply line and the negative power supply line; The voltage between the positive power supply line and the negative power supply line is divided and a reference voltage (for example, a connection point (for example, a connection point N of the first transistor group and the second transistor group for extracting the reference voltage _VREF). ).

[Action]

By adopting the above-described means, even if there is a variation in the characteristics of the transistors constituting the reference voltage generating circuit, particularly, even if there is a variation in the drain current characteristic, the variation in the reference voltage caused by the variation can be made negligibly small, It is suitable for use when performing level conversion between integrated circuit devices having different systems.

〔Example〕

FIG. 3 is a main part circuit diagram of one embodiment of the present invention.
The same symbols as those used in FIGS. 2 and 3 indicate the same parts or have the same meaning.

V _TT In figure shows the voltage at the terminating power to the silicon-based ECL circuit.

In the illustrated example, the group A is configured by connecting six transistors Q11 to Q16 in series, and the group B is configured by connecting three transistors Q21 to Q23 in series and belongs to the group A. Transistor
The voltage divided by one transistor such as Q11 is 0.22
[V] and the transistor Q21 belonging to the group B
It is 0.23 [V], and V _TT = −2.0 [V]
, The reference voltage V _REF of -1.3 [V] from the connection point N
Is obtained. The reason is that the transistor Q2 belonging to the group B
The voltage divided at 1 etc. is higher than that of the transistors Q11 etc. belonging to group A by 0.01 [V], but this is realized by slightly reducing the gate width of the transistors Q21 etc. You.

Each of the transistors Q11... And Q21.
.. Has a normal threshold voltage, ie, -0.5 to -1.0 [V], its IV characteristics will intersect in the triode region as seen in FIG. . Further, the transistors Q11, Q12, ..., Q21, since Q22 drain voltage applied to .... almost equal, there is little change in the V _REF is also deviated from the design value闘値voltage.

〔The invention's effect〕

In the reference voltage generating circuit according to the present invention, a first transistor group including transistors connected in series and a second transistor group including transistors connected in series are connected to a positive power supply line and a negative power supply line. The current-to-voltage characteristics of the first transistor group and the current-to-voltage characteristics of the second transistor group intersect in the current non-saturation region. Has been selected.

By adopting the above configuration, even if the characteristics of the transistors constituting the reference voltage generating circuit, particularly, the drain current characteristics vary, the fluctuation of the reference voltage caused by the variation can be reduced to a negligible level. It is suitable for use in the case of performing level conversion between integrated circuit devices having different values.

[Brief description of the drawings]

FIG. 1 is a main part circuit diagram of a reference voltage generating circuit for explaining the principle of the present invention, FIG. 2 is a diagram for explaining voltage-current characteristics of the reference voltage generating circuit shown in FIG. 1, FIG. 3 is a main part circuit diagram of one embodiment of the present invention, FIGS. 4 and 5 are main part circuit diagrams of a conventional example, and FIG. 6 explains a voltage-current characteristic of the conventional example shown in FIG. Respectively. In the figure, V _SS is the negative power supply voltage, V _REF is the reference voltage, Q1
..., transistors, Q21, Q22 ..., transistors, A: group consisting of transistors Q11, Q12, ..., B: group consisting of transistors Q21, Q22, N: group A a connection point between the B, V _TT denotes the voltage at the terminating power to the silicon-based ECL circuit.

Claims (1)

(57) [Claims] The number of transistors is selected such that the current-voltage characteristics of the series-connected transistors and the current-voltage characteristics of the series-connected transistors intersect in the current non-saturation region. And a first transistor group and a second transistor group interposed between the first power supply line and the second power supply line, and a voltage between the positive power supply line and the negative power supply line to obtain a reference voltage. And a connection point between the first transistor group and the second transistor group.