JPH0832087A - Integrated circuit - Google Patents

Abstract

PURPOSE:To make it possible to compensate the variation of a power gain due to a temperature change of an integrated circuit, without causing complexity of a circuit constitution, which is caused by adding a temperature compensating circuit or the like to the circuit constitution, and an increase in the number of elements. CONSTITUTION:As a resistive material for a resistor 14 connected with an input part of an FET 13, a metal, such as tungsten, iron and nickel, whose resistance value increases with a temperature rise of an integrated circuit, or a laminated material having a hetero-structure is used. By forming the integrated circuit into such a structure, the ratio of the amount of a current, which flows in the side of the resistor 14, is decreased with the temperature rise and the amount of a current, which is inputted in the FET 13, is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated circuit, and more particularly to an integrated circuit capable of compensating for fluctuations in its own power gain due to temperature changes.

[0002]

2. Description of the Related Art In recent years, the demand for integrated circuits having the function of amplifying high frequency signals has increased with the expansion of fields such as mobile communications. In such a circuit, a compound semiconductor FET such as GaAs MESFET is generally used as an amplification element. However, the power gain of the FET decreases as the temperature rises, deteriorating the characteristics of the amplifier. Further, when a matching circuit or the like is provided in the circuit in addition to the FET, the loss due to the increase in the resistance value of the metal wiring used in the matching circuit also results in a decrease in the net input power to the FET, and the loss as an amplifier. This causes a decrease in apparent gain. For these reasons, the rise in temperature causes the deterioration of the characteristics of the integrated circuit having the amplifying effect.

On the other hand, conventionally, as shown in FIG. 7, by adding a gain adjusting FET 103, a room temperature monitor resistor 104, a constant current supplying FET 105, etc., the gate bias is shifted to the positive side according to the temperature rise. In some cases, the increase in mutual conductance is used to compensate for the decrease in power gain due to the temperature rise due to the FET or the like. However, there is a problem that the chip size becomes large due to the complicated circuit configuration and the increase in the number of elements.

On the other hand, a stabilizing resistor having a role of preventing oscillation of the FET is generally connected between the input portion of the FET and the ground plane so that a part of the input power is divided and released to the outside. It Usually, a semiconductor doping layer, an alloy using nickel or the like, and a metal compound such as tantalum oxide are used for the stabilizing resistance. Generally, the resistance value of which has little temperature dependency is selected, and the resistance value is from room temperature to 100%.
Resistance change with temperature rise up to ℃ is at most 1-6%
Is just the rate of increase.

[0005]

As described above, in order to compensate the temperature dependence of the power gain of the integrated circuit having the amplifying action, it is necessary to add a temperature compensating circuit and the like. The problem is that the circuit configuration is complicated and the number of elements is increased. The present invention has been made in view of the above points, and an object of the present invention is to provide an integrated circuit in which the gain variation due to temperature is small in a simple form.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an amplification element for amplifying an input signal, and a temperature change compensating resistor arranged between an input portion of the amplification element and a predetermined potential. Having a body. It is necessary to use, as the resistance material forming this resistor, a material whose resistance value increases by 30% or more with a temperature rise from room temperature to 100 ° C.

[0007]

In this structure, the resistance value of the resistor arranged between the input part of the amplifying element and the predetermined potential increases as its temperature rises, and the amount of current input to this resistor is increased. Is reduced. Therefore, the amount of current input to the amplification element increases, the mutual conductance of the amplification element decreases, the loss due to the increase of the resistance value of the metal wiring, etc. are compensated for, and the fluctuation of the power gain of the integrated circuit due to the temperature change is compensated. It

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic view of a GaHs integrated circuit according to the first and second embodiments of the present invention. This integrated circuit is intended for high frequency signals as input signals. The high frequency signal is input to the input terminal 11, passes through the input matching circuit 12, and is input to the FET 13, which is an amplification element. FET
A GaAs MESFET having a maximum oscillation frequency of 35 GHz at room temperature and a gate width of 4 mm is used as the element 13.
A resistor 14 is connected between the input part of the FET 13 and the ground plane (0V). This resistor 14 is FE
In order to prevent the oscillation of T13, it also plays a role as a stabilizing resistor that splits a part of the input current and releases it to the outside. Finally, the output signal from the FET 13 is the output matching circuit 15
And is output from the output terminal 16.

FIG. 2 is a sectional view of a thin film resistor used as the resistor 14 in the integrated circuit of the first embodiment. This thin film resistor has a cross section of 0.01 μm × 2 μm and a length of 14 μm.
This is a pure metal nickel thin film resistor having a thickness of μm, the resistance value at room temperature is about 50Ω, and it is expected that the resistance value will increase by about 40 to 50% by the temperature change from room temperature to 100 ° C. FIG. 3 shows the temperature dependence of the power gain when using a conventional resistance material having a small temperature dependence as a stabilizing resistance and when using the thin film resistance of this embodiment. As can be seen from FIG. 3, the power gain obtained by the integrated circuit of this embodiment is 15.2 dB at room temperature and 15.0 dB at 100 ° C.
It shows an almost constant value without decreasing as the temperature rises.

This is for the following reason. In the FET 13, the increase of the gate resistance due to the temperature rise causes a decrease of the mutual conductance, and the resistance values of the metal wirings forming the matching circuits 12 and 15 and the transmission path increase. These reduce the power gain of the integrated circuit with increasing temperature. Here, if a resistance material whose resistance value increases as the temperature rises is used as the resistor 14, the ratio of the current value flowing out to the resistor 14 side decreases as the temperature rises. Input current value increases.
Therefore, the increase of the input current of the FET 13 and the decrease of the mutual conductance cancel each other out, and the power gain of the FET 13 does not apparently decrease. Similarly, the matching circuits 12 and 15
Also, the power loss due to the wiring will be compensated.

As described above, according to the present invention, the fluctuation of the power gain due to the temperature change can be suppressed without observing the complication of the circuit for the temperature compensation circuit and the increase of the number of elements.

Here, in the first embodiment, the resistor 1
A pure metal nickel thin-film resistor was used as No. 4, but the present invention is not limited to this, and it is possible to obtain the temperature from room temperature to 1
It suffices if there is an increase in the resistance value required for the circuit used with a temperature change of 00 ° C., for example, pure metal such as tungsten, iron, or copper can be used as the material. Also,
The resistance material is not limited to pure metal, and other materials may be used. Further, if desired, the diffused resistor 30 as shown in FIG. 4 may be used. The diffusion resistance 30 is obtained by adding an impurity of opposite conductivity type to a semiconductor substrate of one conductivity type by ion implantation or the like.

Further, as shown in FIGS. 5 (a) and 5 (b), as the resistor 14, a plurality of metals having different temperature dependences of their resistance values are arranged laterally (FIG. 5 (a)) or vertically. If it is formed continuously in the direction (FIG. 5 (b)),
By appropriately selecting those types, it is possible to match the temperature dependence of the resistance value with the optimum characteristics for compensating the temperature dependence of the power gain of the FET 13 or the like. For example, if the gain decrease with respect to the temperature change of the circuit (20 ° C to 100 ° C) is 45%, this temperature change causes 45%.
A resistor that gives compensation for is formed using Mo and W.
That is, W having a resistance increase of 40% is formed into a film having a thickness of 0.01 μm by a sputtering method, and is subjected to RIE (reactive ion etching) with a fluorine-based gas such as CF4, and the length is 18 μm and the width is 7 μm Of W film 31.
Furthermore, a Ni film with a resistance increase of 50% has a thickness of 0.01 μm.
By depositing on the W film 31 and masking with a resist and performing RIE, N of 18 μm in length and 7 μm in width is formed adjacent to the W film 31.
The i film 32 is formed. With such a structure, the resistor 14 having a predetermined resistance value increase of 45% is formed.

Next, a second embodiment of the present invention will be described with reference to FIGS. 1 and 6. In this embodiment,
Each component shown in FIG. 1 is connected by a transmission line composed of Au-based wiring, and is formed on a semi-insulating GaAs substrate.
In this embodiment, a laminated structure as shown in FIG. 6 is used as the resistor 14, and it also serves as a stabilizing resistor for preventing the oscillation of the FET 13 as in the first embodiment. This laminated structure has an AND-type GaAs layer 42 having a large electron affinity on a GaAs substrate 41 and an electron concentration of 0.5 to 4.0 ×.
N-type Al _x Ga _1-x with a small electron affinity of 10 ¹⁸ cm ^-3
The As layer 43 (x to 0.3) has a heterostructure. Further, ohmic contact electrodes 44, 45 made of AuGe alloy
Are formed on the surface of the Al _x Ga _1-x As layer 43. In the present embodiment, electric conduction by a two-dimensional electron gas generated at the interface of the heterojunction between the n-type Al _x Ga _1-x As layer 43 and the GaAs layer 42 is used. In such a structure, the two-dimensional electron gas concentration at the heterojunction interface is 1.0 to 1.5 × 10.
^The sheet resistance is ¹² cm ^-2 and the sheet resistance at room temperature is 600 to 900 Ω / □. Here, a desired resistance value can be given by appropriately setting the aspect ratio. In the case of this embodiment, it is set to about 55Ω.

Since the two-dimensional electron gas is separated from the ionized impurities, basically the ions do not undergo impurity scattering. That is, since phonon scattering is dominant, the resistance greatly increases as the temperature rises. For example, from room temperature to 100
When the temperature rises to ℃, this electric resistance increases by about 40%.
By utilizing this characteristic and using it as a stabilizing resistor, the electric power released to the ground side is reduced as the temperature rises, and the input current value to the FET is increased. By doing so, the gain reduction of the FET can be apparently suppressed.

When a signal of f = 1.9 GHz was input to the integrated circuit shown in FIG. 1 by using the stabilizing resistor having the above structure, the gain at room temperature was 15.1 dB. Next, when the ambient temperature was raised to 100 ° C. and a new measurement was performed, it was 15.0 dB, which was almost unchanged.

The reason why the effect is obtained in this embodiment is as follows. That is, the signal loss is increased due to the decrease in the amplification characteristic of the FET 13 with the temperature rise and the increase in the resistance of the Au-based wirings that form the matching circuits 12 and 15 and the transmission line. This is because the resistance value of the resistor 14 connected in parallel to the gate terminal increases, the input power value to the FET 13 increases, and the effects of the both cancel each other out.

As described above, by using the laminated structure of the semi-insulating layers as the stabilizing resistor, it is possible to obtain a high frequency amplifier integrated circuit having a simple structure and a small gain variation due to temperature. As a heterostructure of the above-mentioned laminated structure, an and-type GaAs layer 42 and an n-type Al _x Ga _1-x As layer 43 ( _{x to}
Not limited to the combination of 0.3), any material may be used as long as it has a desired temperature coefficient of resistance. For example, the I and
An n _x Ga _1-x As layer may be used, and the n-type Al _x Ga _1-x As layer 43 of the above embodiment is not limited to _{x to} 0.3.

Further, it is possible to combine the above-mentioned laminated structure with a compound semiconductor layer to which an impurity is added. For example, a GaAs layer of high impurity concentration having a small temperature coefficient near room temperature is combined with the above-mentioned laminated structure. This makes 2
By using the electric conduction by the dimensional electron gas and the electric conduction of the GaAs layer to the same degree, it is possible to cope with various temperature ranges and temperature dependence of gain.

Further, in each of the above-mentioned embodiments, F is used as an amplifying element.
Although the ET is used, the input signal is not limited to the high frequency, and the present invention can be applied to other amplifying elements whose gain decreases as the ambient temperature rises, and the above-mentioned effects can be obtained similarly.

[0021]

According to the present invention, fluctuations in the gain characteristics of an integrated circuit due to a decrease in gain of an amplifier element due to a temperature rise and an increase in loss due to a matching circuit and wiring can be compensated for in a simple form.

[Brief description of drawings]

FIG. 1 is a circuit diagram for explaining an integrated circuit according to first and second embodiments of the present invention.

FIG. 2 is a sectional view of a thin film resistor used as a stabilizing resistor in the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing the temperature dependence of the power gain of the first embodiment of the present invention and the conventional integrated circuit.

FIG. 4 is a cross-sectional view of a resistor having a diffusion resistance used as a stabilizing resistor in the first embodiment of the present invention.

FIG. 5 is a sectional view of a resistor having a laminated structure of pure metal used as a stabilizing resistor in the first embodiment of the present invention.

FIG. 6 is a sectional view of a laminated structure of a semi-insulating layer used as a stabilizing resistor in the second embodiment of the present invention.

FIG. 7 is a circuit diagram for explaining a conventional technique of the present invention.

[Explanation of symbols]

 11 ... Input terminal 12 ... Input matching circuit 13 ... FET 14 ... Stabilizing resistor 15 ... Output matching circuit 16 ... Output terminal 17 ... Metal 18 ... Metal wiring 19・ ・ ・ Insulating film 30 ・ ・ ・ Diffusion resistance 31 ・ ・ ・ Metal film A 32 ・ ・ ・ Metal film B

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masami Nagaoka, No. 1 Komukai Toshiba Town, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Corporate Research & Development Center, Toshiba Corporation (72) Kenji Ishida Komukai Toshiba, Kawasaki City, Kanagawa Prefecture Town No. 1 Toshiba Corporation Research & Development Center

Claims (8)

[Claims] 1. An integrated circuit comprising: an amplifying element for amplifying an input signal; and a temperature change compensating resistor arranged between an input portion of the amplifying element and a predetermined potential. 2. The integrated circuit according to claim 1, wherein the amplification element is a FET. 3. The integrated circuit according to claim 1, wherein the resistor is formed by combining a plurality of metal films whose resistance values have different temperature dependences. 4. The integrated circuit according to claim 1, wherein the signal input to the amplifying element is a high frequency signal. 5. The resistor has a laminated structure of a first compound semiconductor layer to which an n-type impurity is added and a second compound semiconductor layer having an electron affinity higher than that of the first compound semiconductor layer. 2. The integrated circuit according to claim 1, wherein a two-dimensional electron gas generated at the interface between the first compound semiconductor layer and the second compound semiconductor layer is used for main electrical conduction. 6. The resistor has a laminated structure of the first compound semiconductor layer and the second compound semiconductor layer, and the first compound semiconductor layer.
Of the third compound semiconductor layer having an electron affinity larger than that of the compound semiconductor layer and having an n-type impurity added, and using the two-dimensional electron gas and the third compound semiconductor layer for main electrical conduction. The integrated circuit according to claim 1, which is characterized in that: 7. An amplifying element for amplifying an input signal, and a resistor arranged between an input portion of the amplifying element and a predetermined potential, the resistor having a resistance value of room temperature to 100 ° C. An integrated circuit comprising a resistance material that increases by at least 30% or more with respect to a change. 8. The resistor is made of at least one of tungsten, copper and nickel.
The integrated circuit described.