JPH11251584A - Transistor and high frequency amplifier employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve characteristics, e.g. distortion or noise factor, over a wide frequency range by dividing an active region into at least two regions and forming a gate electrode independently in each divided region. SOLUTION: Two active regions 12a, 12b are formed on a semiconductor substrate 11 followed by formation of a source region and a drain region, respectively, thereon. A source electrode 13 and a drain region 14 formed on the active regions 12a, 12b are connected common and gate electrodes 15a, 15b formed on the active regions 12a, 12b are separated independently. Furthermore, a capacitor is connected between the gate electrodes 15a, 15b. Since the gate electrodes are formed independently on respective active regions, respective gate electrodes can be connected with different DC voltage sources. Consequently, the operating region of the active region, and thereby the gate width, can be varied by turning the DC voltage sources on/off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field effect transistor (FET) or a bipolar transistor and a high frequency amplifier using the same.

[0002]

2. Description of the Related Art Hitherto, in order to widen the operating frequency of a high-frequency amplifier, a method of improving the frequency characteristics by, for example, increasing the number of stages of a low-pass filter of an output matching circuit of an FET has been often used.

A conventional high-frequency amplifier will be described with reference to a circuit diagram shown in FIG. In this configuration, a gate terminal 2 of a field effect transistor 1 having a conventional structure is connected to an input terminal 4 via an input matching circuit 3 and a gate power supply circuit 5
, The source terminal 6 is grounded, the drain terminal 7 is connected to the output terminal 9 via the output matching circuit 8, and the drain power supply circuit 10.

With this configuration, the high-frequency signal input to the input terminal 4 is input to the field effect transistor 1 without being reflected by the input matching circuit 3 and is amplified. The amplified high-frequency signal is output from the output terminal 9 via the output matching circuit 8 without loss.

[0005]

The high-frequency amplifier having the above-mentioned conventional configuration aims to increase the operating frequency by widening the bandwidth of the matching circuit.

However, in the above-described conventional configuration, there is a problem that there is a limit to the expansion of the band, and when the band is widened, the loss of the matching circuit increases and the efficiency of the high-frequency amplifier decreases.

An object of the present invention is to provide a new transistor configuration, and to provide a wideband high-frequency amplifier while suppressing loss by using the same.

[0008]

In order to achieve the above object, a field effect transistor according to the present invention comprises:
A plurality of source and drain regions are formed on an active layer region formed on a semiconductor substrate, a source electrode is formed on the source region, and a drain electrode is formed on the drain region. First in some areas of
Is formed, and a second gate electrode is formed in the remaining region of the active layer region.

Thus, since there are two independent gate electrodes in the active region, the operating range of the active region is controlled by voltage control for conducting or blocking (hereinafter, referred to as on / off) the voltage applied to each gate electrode. Therefore, the transistor characteristics can be changed.

A high frequency amplifier according to the present invention uses the field effect transistor according to the present invention, a capacitor is connected between the first and second gate electrodes, and the first gate electrode is connected to an input terminal via an input matching circuit. Connected to the first DC voltage source circuit, the second gate electrode is connected to the controllable second DC voltage source circuit, and the drain electrode is connected to the output terminal via the output matching circuit. Is what it is.

[0011] Thus, by turning on / off the voltage applied to the second gate electrode by the controllable second DC voltage source circuit connected to the second gate electrode, a part of the active layer region is formed. By changing the gate width by operating or disabling the device, the output impedance of the field-effect transistor is changed, and matching with the output circuit can be achieved in accordance with the operating frequency, thereby enabling wide-band amplification operation. .

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a structure of a field-effect transistor according to a first embodiment of the present invention.

In this structure, two active regions 12a and 12b are formed on a semiconductor substrate 11, and the active regions 12a and 12b
2b, a source region and a drain region are respectively formed, and a source electrode 13 commonly connected to the source region is
A drain electrode 14 connected in common is formed on the drain region, a gate electrode 15a is formed on the active region 12a, and a gate electrode 15b is formed on the active region 12b. Further, the lower electrode 16 connected to the gate electrode 15a
And a capacitor formed of an upper electrode 17 connected to the gate electrode 15b and a ferroelectric material 18 formed therebetween.

That is, the source electrode and the drain electrode formed on the active regions 12a and 12b are commonly connected to each other, the gate electrodes formed on the active regions 12a and 12b are separated and independent, and a capacitor is provided between the gate electrodes. Are connected.

According to this structure, since the gate electrodes formed on the respective active regions are separated and independent, different DC voltage sources can be connected to the respective gate electrodes, and the DC voltage sources are turned on / off. By doing so, the operation region of the active layer region can be changed, that is, the gate width can be changed, and characteristics of three types of transistors can be obtained.

In addition, a field effect transistor which can be connected at a high frequency and to which a different bias voltage can be applied DC-wise can be manufactured by connecting the separated and independent gate electrodes in series on a semiconductor substrate by a capacitor. .

Although the degree of integration is low, an external capacitor may be used. In that case, a capacitor having a large capacity value can be installed.

In this embodiment, the case where the number of separated active layer regions is two has been described, but three or more active layer regions may be provided. In this case, the gate width can be changed by changing on / off combinations of the DC voltage sources connected to the respective independent gate electrodes to change the operation regions of various types of active layer regions. The characteristics of the transistor can be obtained.

(Embodiment 2) FIG. 2 shows the structure of a field effect transistor according to a second embodiment of the present invention.

In this structure, an active region 12 is formed on a semiconductor substrate 11, a source region and a drain region are formed on the active region 12, and a source electrode 13 commonly connected on the source region is formed on the drain region. A commonly connected drain electrode 14 is formed, the active region 12 is divided into two, a gate electrode 15a commonly connected to one region is formed, and a gate electrode 15b commonly connected to the other region.
Is formed. Further, a lower electrode 16 connected to the gate electrode 15a, an upper electrode 17 connected to the gate electrode 15b, and a ferroelectric material 18 formed therebetween.
Is formed.

That is, in a single field effect transistor structure, only the gate electrode is separated into two independent parts.
It has a structure in which a capacitor is connected between gate electrodes.

In this structure, the same operation and effect as described in the first embodiment are exhibited, and the number of active regions is reduced to one. Therefore, the size of the field effect transistor can be further reduced. However, since the active regions are not separated, they are easily affected by the two transistors.

(Embodiment 3) FIG. 3 shows a structure of a field-effect transistor according to a third embodiment of the present invention.

In this structure, the respective source electrodes 13 formed on the active regions 12a and 12b of the field effect transistor are not connected in common by metal wiring on the semiconductor substrate 11 as shown in FIG. In the case of an integrated circuit, it is commonly connected to a bonding pad 39 (an internal lead outside the semiconductor substrate 11 in the case of a package) formed on an insulating substrate outside the semiconductor substrate 11 by a thin metal wire (wire) 40. Drain electrodes 14 formed on regions 12a and 12b are commonly connected to bonding pad 41 by thin metal wire 40, and a gate electrode 15 formed on active regions 12a and 12b is formed.
a and 15b are separated and independent, are connected to separate bonding pads 42a and 42b by thin metal wires 40, and a capacitor is connected between gate electrodes.

Also in this structure, the same operation and effect as described in the first embodiment are exhibited. Similarly, in the field-effect transistor having the structure shown in FIG. 2, the source electrode and the drain electrode are respectively formed by electrodes outside the semiconductor substrate (in the case of a hybrid integrated circuit, bonding electrodes formed on an insulating substrate on which the semiconductor substrate is mounted). Pads and internal leads in the case of packages) can be commonly connected by thin metal wires.

The field effect transistor (FET) described above may be a MOS FET, a Schottky FET or a junction FET.

(Embodiment 4) FIG. 4 shows the structure of a bipolar transistor according to a fourth embodiment of the present invention.

In this structure, an isolated island region collector region 19 is formed on the semiconductor substrate 11, and two base regions 20a and 20b are formed in the collector region 19.
An emitter region 21 is formed in each base region, a collector electrode 22 is formed on the collector region 19, an emitter electrode 23 connected in common is formed on the emitter region 21, and a common electrode is formed on the base region 20a. The connected base electrode 24a is formed, and the base region 20b is formed.
And a base electrode 24b connected in common is formed thereon.

Further, the lower electrode 16 connected to the base electrode 24a and the upper electrode 1 connected to the base electrode 24b.
7 and a capacitor made of a ferroelectric 18 formed therebetween. Note that a region marked with a cross indicates a contact region.

According to this structure, since the base electrodes formed on the respective base regions are separated and independent, different DC voltage sources can be connected to the respective base electrodes, and the DC voltage sources can be turned on / off. By letting
By changing the operation region of the base region, the size of the operation transistor is changed to obtain characteristics of three types of transistors.

Further, a bipolar transistor which is connected at a high frequency by applying a separate and independent base electrode in series on a semiconductor substrate by a capacitor and which can apply a different bias voltage in a DC manner can be manufactured.

Although the present embodiment has been described with reference to the case where there are two separated base regions, three or more base regions may be provided. In this case, it is possible to change the operation region of various types of base regions by combining on / off of a DC voltage source connected to each independent base electrode, and obtain characteristics of various types of transistors. Can be.

(Embodiment 5) FIG. 5 shows a structure of a bipolar transistor according to a fifth embodiment of the present invention.

In this structure, an isolated island region collector region 19 is formed on a semiconductor substrate 11, a base region 20 is formed in the collector region 19, and a base region 20 is formed.
A plurality of emitter regions 21 are formed in the inside, a collector electrode 22 is formed on the collector region 19, and the emitter region 2 is formed.
1, an emitter electrode 23 connected in common is formed, the base region 20 is divided into two regions, a base electrode 24a connected in common to one region is formed, and a common connection is made to the other region. The base electrode 24b is formed. Further, the lower electrode 16 connected to the base electrode 24a and the upper electrode 17 connected to the base electrode 24b.
And a capacitor made of the ferroelectric 18 formed therebetween.

In this structure, the same operation and effect as those described in the fourth embodiment are obtained, and the base region is set to one.
Therefore, the size of the bipolar transistor can be further reduced. However, since the base region is not separated, the two transistors are easily affected by each other.

(Embodiment 6) FIG. 6 is a circuit diagram of a high-frequency amplifier according to a sixth embodiment of the present invention.

This configuration uses the field effect transistor 25 shown in the first, second or third embodiment, and
Is connected to the gate voltage source circuit 27a, and the second gate terminal 26b is connected to the gate voltage source circuit 27b.
Connected to the input terminal 29 via the input matching circuit 28, the drain terminal 30 is connected to the drain voltage source 31, the output terminal 33 is connected via the output matching circuit 32, and the source terminal 34 Is grounded. Note that a resistor 43 is connected between the first gate terminal 26a and the second gate terminal 26b.

Hereinafter, the operation principle of the high frequency amplifier according to the sixth embodiment of the present invention will be described.

First, the voltage applied from the gate voltage source circuit 27a is Vgg1, the voltage applied from the gate voltage source circuit 27b is Vgg2, and the voltage applied from the drain voltage source circuit 31 is Vdd. The voltage Vgg2, the voltage Vdd, the input matching circuit 28, and the output matching circuit 32 are determined by characteristics required for the high-frequency amplifier, and the voltage Vgg1 is the first gate of the field effect transistor having the first and second gate electrodes. It is determined to activate or deactivate the active region having the electrodes.

Input matching circuit 28 and output matching circuit 32
Is designed in accordance with the input / output impedance of the field-effect transistor 25 so that desired characteristics such as gain, distortion, or noise figure can be obtained in a frequency range desired by the high-frequency amplifier.

Here, FIG. 7 shows frequency characteristics in a case where a design is made so as to obtain a desired amplification characteristic in a band of frequencies f1 to f2 in a state where all the active regions are operating.

FIG. 7A shows the frequency characteristic of the gain.
FIG. 7B shows frequency characteristics of distortion or noise figure. The area indicated by the arrow in the drawing is an area where desired characteristics are obtained.

The gate voltage Vgg1 is applied to the first gate terminal 26a.
When the voltage is such that the operation of the active region of the first gate electrode connected to the
5 is equivalent to a state where the gate width is reduced, and the input / output impedance is also changed. This changed impedance is matched with the input matching circuit 28 and the output matching circuit 32 in the frequency band of f3 to f4, and each matching circuit and gate width are set so that desired amplification characteristics such as gain, distortion or noise figure are obtained. , A high-frequency amplifier that obtains desired characteristics in two operating frequency bands of frequencies f1 to f2 and frequencies f3 to f4 can be obtained as shown in FIG.

Further, as shown in FIG. 9, if the two operating frequency bands are designed to overlap each other, good gain, distortion or noise can be obtained in a wide frequency band which cannot be obtained by the conventional widening technique of frequencies f3 to f2. A high frequency amplifier having characteristics such as an index can be obtained.

That is, in the operating region of the frequencies f3 to f4, the gate voltage Vgg1 is set to a voltage at which the operation of the active region of the first gate electrode connected to the first gate terminal 26a becomes inoperable. F2, the gate voltage Vgg1 and the gate voltage Vgg2 are applied to the first gate terminal 2
The voltage is set so that the active regions of both the first gate electrode and the second gate electrode connected to 6a and the second gate terminal 26b operate.

Although only one high-frequency amplifier is formed in the high-frequency amplifier shown in FIG. 6, a larger gain can be obtained by connecting two or more high-frequency amplifiers in series to form a multi-stage high-frequency amplifier. A wide-band high-frequency amplifier can be realized.

(Embodiment 7) FIG. 10 is a circuit diagram of a high-frequency amplifier according to a seventh embodiment of the present invention.

This circuit diagram is different from the circuit diagram shown in FIG. 6 in that the field effect transistor 25 is replaced with the bipolar transistors 35 shown in the fourth and fifth embodiments, and how to apply the base voltage is changed. It is a little changed. Thus, 36a is a first base terminal, 36b is a second base terminal, 37 is a collector terminal, and 38 is an emitter terminal.

When a base voltage is applied instead of the gate voltage and the base voltage Vgg1 is set to a voltage at which the operation of the active region of the first base electrode becomes inoperable, the emitter region of the bipolar transistor becomes smaller. This is equivalent to a state, and the transistor characteristics change.

In this manner, a high-frequency amplifier having good gain, distortion, noise figure, and other characteristics in a wide frequency band can be obtained by the same operation as described in the sixth embodiment.

[0052]

By using the transistor of the present invention to form the high-frequency amplifier of the present invention, a high-frequency amplifier having good gain, distortion, noise figure, and other characteristics in a wide frequency band that cannot be obtained by the conventional widening method. An amplifier can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a field-effect transistor according to a first embodiment of the present invention.

FIG. 2 is a plan view of a field-effect transistor according to a second embodiment of the present invention.

FIG. 3 is a plan view of a field-effect transistor according to a third embodiment of the present invention.

FIG. 4 is a plan view of a bipolar transistor according to a fourth embodiment of the present invention.

FIG. 5 is a plan view of a bipolar transistor according to a fifth embodiment of the present invention.

FIG. 6 is a circuit diagram of a high-frequency amplifier according to a sixth embodiment using the field-effect transistor of the present invention.

FIG. 7 is a frequency characteristic diagram in a state where all active regions of the field-effect transistor are operating in the high-frequency amplifier shown in FIG. 6;

8 is a frequency characteristic diagram of the high-frequency amplifier shown in FIG. 6 in a state where all the active regions of the field effect transistor are operating and in a state where a part of the active region is inactive.

9 is a frequency characteristic in which the frequency characteristics of the high-frequency amplifier shown in FIG. 6 are continuous between two states in which all the active regions of the field-effect transistor are operating and two states in which part of the active region is inactive. Figure

FIG. 10 is a circuit diagram of a high-frequency amplifier according to a seventh embodiment using the bipolar transistor of the present invention.

FIG. 11 is a circuit diagram of a conventional high-frequency amplifier.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 semiconductor substrate 12, 12a, 12b active region 13 source electrode 14 drain electrode 15a, 15b gate electrode 16 lower electrode 17 upper electrode 18 ferroelectric 19 collector region 20, 20a, 20b base region 21 emitter region 22 collector electrode 23 emitter electrode 24a, 24b Base electrode 25 Field effect transistor 26a First gate terminal 26b Second gate terminal 27a First gate voltage source circuit 27b Second gate voltage source circuit 28 Input matching circuit 29 Input terminal 30 Drain terminal 31 Drain voltage Source circuit 32 Output matching circuit 33 Output terminal 34 Source terminal 35 Bipolar transistor 36a First base terminal 36b Second base terminal 37 Collector terminal 38 Emitter terminal 39, 41, 42a, 42b Bonding pad De 40 thin metal wire 43 resistance

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 29/812 21/338 H03F 3/189

Claims (12)

[Claims] A plurality of source and drain regions are formed on an active layer region formed on a semiconductor substrate, and a source electrode is commonly connected on the source region, and a drain electrode is commonly connected on the drain region. A field effect transistor formed, wherein the active layer region is divided into at least two or more regions, and independent gate electrodes are respectively formed on the divided active layer regions. 2. A plurality of source and drain regions are formed on at least two or more active layer regions formed on a semiconductor substrate. A source electrode is formed on the source region, and a drain electrode is formed on the drain region. Are formed in common connection, and independent gate electrodes are formed on the respective active layer regions. 3. The field effect transistor according to claim 1, wherein the source electrode and the drain electrode are connected in common on the semiconductor substrate by metal wiring. 4. The field effect transistor according to claim 1, wherein the source electrode and the drain electrode are commonly connected to an electrode outside the semiconductor substrate by a thin metal wire. 5. The semiconductor device according to claim 1, wherein the independent gate electrodes are connected via a capacitor formed on the semiconductor substrate or a capacitor provided outside the semiconductor substrate. Field effect transistor. 6. A base region is formed in a collector region formed on a semiconductor substrate, a plurality of emitter regions are formed in the base region, and an emitter electrode commonly connected is formed on the emitter region. A collector electrode is formed on the collector region, and the base region
A bipolar transistor, wherein an independent base electrode is formed on each of the divided base regions. 7. At least two or more base regions are formed in a collector region formed on a semiconductor substrate, emitter regions are formed in each of the base regions, and emitters are commonly connected on the emitter regions. A bipolar transistor, wherein an electrode is formed, a collector electrode is formed on the collector region, and an independent base electrode is formed on each of the base regions. 8. The semiconductor device according to claim 6, wherein the independent base electrodes are connected to each other via a capacitor formed on the semiconductor substrate or a capacitor provided outside the semiconductor substrate. Bipolar transistor. 9. A plurality of source and drain regions are formed on an active layer region formed on a semiconductor substrate, and a source electrode is commonly connected on the source region, and a drain electrode is commonly connected on the drain region. A field-effect transistor in which the active layer region is divided into two regions, independent gate electrodes are formed on the divided active layer regions, and a capacitor is connected between the independent gate electrodes. , One of the gate electrodes is connected to an input terminal via an input matching circuit and connected to a first DC voltage source circuit, and the other gate electrode is controllable in a second DC voltage source circuit. And the drain electrode is connected to an output terminal via an output matching circuit. 10. A plurality of source and drain regions are formed on two active layer regions formed on a semiconductor substrate, and a source electrode is connected to the source region and a drain electrode is connected to the drain region. Formed
In the field effect transistor in which an independent gate electrode is formed on each of the two active layer regions and a capacitor is connected between the independent gate electrodes, one of the gate electrodes is connected to an input terminal via an input matching circuit. Connected to a first DC voltage source circuit, the other gate electrode is connected to a controllable second DC voltage source circuit, and the drain electrode is connected to an output terminal via an output matching circuit. A high-frequency amplifier characterized by: 11. A base region is formed in a collector region formed on a semiconductor substrate, a plurality of emitter regions are formed in the base region, and an emitter electrode commonly connected is formed on the emitter region. A collector electrode is formed on the collector region, the base region is divided into two regions, independent base electrodes are formed on the respective divided base regions, and a capacitor is connected between the independent base electrodes. In the bipolar transistor, one base electrode is connected to an input terminal via an input matching circuit and connected to a first DC voltage source circuit, and the other base electrode is connected to a second voltage controllable second terminal. The collector electrode is connected to a DC voltage source circuit or a DC current source circuit, and the collector electrode is connected to an output terminal via an output matching circuit. High-frequency amplifier, wherein the door. 12. A base region is formed in a collector region formed on a semiconductor substrate, an emitter region is formed in each of the base regions, and a commonly connected emitter electrode is formed on the emitter region. A collector electrode is formed on the collector region, an independent base electrode is formed on each of the base regions,
In a bipolar transistor in which a capacitor is connected between the independent base electrodes, one of the base electrodes is connected to an input terminal via an input matching circuit and connected to a first DC voltage source circuit, and the other is connected to a first DC voltage source circuit. The high-frequency amplifier according to claim 1, wherein the base electrode is connected to a second DC voltage source circuit or a DC current source circuit capable of voltage control, and the collector electrode is connected to an output terminal via an output matching circuit.