JPH05121908A - Microwave circuit - Google Patents

Abstract

PURPOSE:To provide the microwave circuit connected to ground in an excellent ground even at a high frequency over 1GHz and to eliminate the effect of a parasitic line to an input and an output side of each lumped constant line and an active element forming the circuit. CONSTITUTION:Ground conductors 1a, 1b are extended in the vicinity of both sides of line conductors 6, 6,... interconnecting ground conductors 1a, 1b to each of lumped constant lines 4, 5 and an active element 10 from the surrounding part of a board 20. A strip shaped bridge conductor 11 is provided onto each line conductor 6 to connect ends of the ground conductors 1a, 1b toward the line conductor 6. Thus, a coplaner line 13 is formed to the input side and the output side of each of the lumped constant lines 4, 5 and the active element 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave circuit, and more specifically, it is constructed by providing a distributed constant line such as a coplanar line, a lumped constant line such as an inductor and a capacitor, and an active element such as a transistor on a dielectric substrate. Related to microwave circuits.

[0002]

2. Description of the Related Art Recently, dielectric substrates (high resistivity semiconductor substrates)
A microwave circuit configured by mixing a distributed constant line such as a coplanar line, a lumped constant line such as an inductor and a capacitor, and an active element such as a transistor and a diode is put into practical use. For example, as shown in FIG.
There is one in which a coplanar line 103, an inductor 104, a capacitor 105, and a transistor 110 are provided on a semiconductor substrate 120. These coplanar lines 1
03, the inductor 104, and the capacitor 105 form an input matching circuit 130, a series feedback circuit 140, and an output matching circuit 150. A ground conductor 101 is provided on the periphery of the substrate surface. This ground conductor 101 is
It is divided into two ground conductors 101a and 101b at the input and output side coplanar lines 103 and 103. The coplanar line 103 includes the ground conductors 101a and 101b,
The center conductor 102 and the strip-shaped bridge conductor 111 provided on the center conductor 102 are included. In addition, a connection portion between the inductor 104 and the capacitor 105, a connection portion between the inductor 104 and the inductor 104, the inductor 1
04 and the transistor 110 are connected to each other by a linear line conductor 106. This microwave circuit can be constructed inexpensively and in a small size, and can perform microwave amplification and the like.

[0003]

However, in the above-mentioned conventional microwave circuit, the ground conductor 101 on the substrate surface is
Since it is divided into two ground conductors 101a and 101b (may be divided into three or more), good grounding is difficult at a high frequency of 1 GHz or higher. In addition, since the connecting portion between the inductor 104 and the capacitor 105, the connecting portion between the inductor 104 and the inductor 104, and the connecting portion between the inductor 104 and the transistor 110 are simply connected by the linear line conductor 106, they float. Since a parasitic line is added, it is difficult to obtain good circuit performance at a frequency where the length of the line conductor 106 cannot be ignored.

Therefore, an object of the present invention is to perform good grounding even at a high frequency of 1 GHz or higher, and to eliminate the influence of parasitic lines on the input side and output side of each lumped constant line and active element. It is to provide a microwave circuit.

[0005]

To achieve the above object, the first invention comprises a lumped constant line and an active element connected to the surface of a dielectric substrate by a linear line conductor, A microwave circuit in which a lumped constant line and a ground conductor integrally surrounding an active element are provided in the peripheral portion of the substrate surface, and a coplanar line is formed in the gap formed by dividing the ground conductor to perform input and output of the entire circuit. In, while extending the ground conductor from the peripheral portion of the substrate to the vicinity of both sides of each of the line conductors, a strip-shaped bridge conductor is provided on each of the line conductors to connect the end portions of the ground conductors on the line conductor side to each other. Then, a coplanar line is configured on the input side and the output side of each of the lumped constant lines and active elements.

A second aspect of the present invention is a ground conductor which has a lumped constant line and an active element connected to the surface of a dielectric substrate by a linear line conductor, and surrounds the lumped constant line and the active element as one body. In the microwave circuit in which a coplanar line is formed in a gap formed by dividing the ground conductor to perform input and output of the entire circuit, a ground conductor is entirely provided on the back side of the substrate. And electrically connecting this ground conductor to the ground conductor on the front surface side of the substrate through a via hole penetrating the board, and the lumped constant line and The feature is that strip lines are configured on the input side and the output side of the device.

[0007]

In the microwave circuit of the first invention, coplanar lines are provided on the input side and the output side of each lumped constant line and active element, and the ends of the ground conductors existing on both sides of each line conductor are bridge conductors. It is connected. Therefore,
The potentials of the grounding conductors become equal in the vicinity of both sides of each line conductor, and good grounding is achieved even at high frequencies above IGHz. Moreover, the coplanar line determines the characteristic impedances of the lumped constant lines and the line conductors on the input side and the output side of the active element, thereby eliminating the influence of the parasitic line.

In the microwave circuit of the second invention, the ground conductor is provided on the entire back surface of the substrate, and the ground conductor and each line conductor constitute a strip line. Therefore, the propagation mode of each line conductor and the lumped constant line becomes a strip line mode, and grounding is performed well even at a high frequency of IGHz or higher. Moreover, the stripline determines the characteristic impedances of the lumped constant circuits and the line conductors on the input side and the output side of the active element, thereby eliminating the influence of the parasitic line.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The microcircuit of the present invention will be described in detail below with reference to embodiments.

FIG. 1 shows a layout of a main part of a microwave circuit according to an embodiment of the first invention. This microwave circuit has an input matching circuit 30, a transistor 10 as an active element, a series feedback circuit 40, an output matching circuit (or an interstage matching circuit) on the surface of a dielectric substrate (high specific resistance semiconductor substrate) 20. The same shall apply hereinafter.) 50. Input matching circuit 30, series feedback circuit 40, output matching circuit 50
Is composed of a spiral inductor 4 and a capacitor 5 as a lumped constant line, and a coplanar line 3 as a distributed constant line, as in the conventional case. Connection between the inductor 4 and the capacitor 5, connection between the inductor 4 and the inductor 4, inductor 4 and the transistor 1
Straight line conductors 6 are provided at the connecting portions with 0, respectively. Further, the ground conductor 1 is provided in the peripheral portion of the substrate surface. The ground conductor 1 is divided into two ground conductors 1a and 1b at the input side and output side coplanar lines 3 and 3, respectively. The coplanar line 3 includes the ground conductors 1a and 1
b, the central conductor 2, and a strip-shaped bridge conductor 11 provided on the central conductor 2. The ground conductors 1a and 1b extend from the periphery of the board to the vicinity of both sides of each of the line conductors 6. A strip-shaped bridge conductor 11 is provided on each line conductor 6, and by this bridge conductor 11,
The ends of the ground conductors 1a and 1b on the line conductor 6 side are connected to each other. As a result, the coplanar line 13 is formed at the connection part on the input side and the output side of each element 4, 5, 10. Therefore, the potentials of the ground conductors 1a and 1b are equal near both sides of each line conductor 6, and good grounding can be performed even at a high frequency of IGHz or higher. Moreover, the coplanar line 13 can determine the characteristic impedance of the line conductors 6 on the input side and the output side of each of the elements 4, 5, 10 and can eliminate the influence of the parasitic line.
Therefore, it is possible to easily design a circuit having desired performance.

In order to investigate the characteristics of the microwave circuit according to the first aspect of the present invention, FIG.
The circuit shown in Figure 2 is laid out in two stages, and as the transistor 10, an ion implantation type field effect transistor (having an NFmin (minimum noise figure) of 1.3 dB at 12 GHz and a gain of 9 dB at minimum noise) is used. 11-13 GHz
A two-stage low noise amplifier was manufactured. And input / output V
When the SWR (standing wave ratio) characteristic, the gain characteristic, and the noise characteristic were measured, as shown in FIG.
Input VSWR 2.5 or less, output VSWR 2.0 or less at Hz,
Low noise with gain above 16dB and noise figure below 2.5dB
We were able to obtain high gain characteristics.

FIG. 2 shows a layout of a main part of a microwave circuit according to an embodiment of the second invention. In this microwave circuit, an input matching circuit 30 and an input matching circuit 30 are provided on the surface of a dielectric substrate (high specific resistance semiconductor substrate) 20 as in the case shown in FIG.
Transistor 10 as an active element and series feedback circuit 4
0 and output matching circuit (or interstage matching circuit. The same applies below)
Equipped with 50. The input matching circuit 30, the series feedback circuit 40, and the output matching circuit 50 are composed of a spiral inductor 4 and a capacitor 5 as a lumped constant line, and a coplanar line 3 as a distributed constant line, as in the conventional case. .. Straight line conductors 6 are provided at the connection between the inductor 4 and the capacitor 5, at the connection between the inductor 4 and the inductor 4, and at the connection between the inductor 4 and the transistor 10. Further, the ground conductor 1 is provided in the peripheral portion of the substrate surface. The ground conductor 1 is divided into two ground conductors 1a and 1b at the input side and output side coplanar lines 3 and 3. The coplanar line 3 includes ground conductors 1a and 1b, a center conductor 2, and a strip-shaped bridge conductor 11 provided on the center conductor 2. Further, in this example, the ground conductor 100 is provided on the entire back surface of the substrate 20. further,
Via holes 12 formed in the periphery of the semiconductor substrate 20,
The ground conductor 100 on the rear surface side and the ground conductors 1a, 1b on the front surface side of the substrate are electrically connected through 12, ... As a result, the line conductors 6 on the front surface of the substrate and the ground conductor 100 on the rear surface of the substrate form the microstrip lines 16 on the input side and the output side of the elements 3, 4, 5, and 10. Therefore, the propagation mode of the inductor 4, the capacitor 5, and the line conductor 6 becomes the mode of the microstrip line, and the grounding is performed well even at a high frequency. Moreover,
The characteristic impedance of the line conductor 6 is determined, and the influence of the parasitic line is removed.

The characteristics of the microwave circuit are substantially the same as those of the microwave circuit shown in FIG. 3, and the frequency bands 11 to 13 GHz formed on the GaAs semiconductor substrate 20 are used.
Even when a two-stage low noise amplifier for use in the system is constructed, substantially the same characteristics can be obtained.

In this example (second invention), the propagation mode of the lumped constant line of the inductor 4 and the capacitor 5 is the mode of the microstrip line, and as a result, when the ground conductor 100 is not provided on the back surface of the substrate. Changes with respect to the propagation mode of. However, the change in this property is slight. However, in order to make a more accurate design, a TEG (test element group) of a lumped constant line in which the ground conductor 100 is provided on the back surface of the substrate is created and evaluated in advance,
The high frequency characteristics of the TEG are used for design.

[0015]

As is apparent from the above, in the microwave circuit of the first invention, the ground conductor existing in the peripheral portion of the substrate surface is extended near both sides of the line conductor connecting the respective elements, and the above-mentioned ground is provided. Since the ends of the conductors on the line conductor side are connected to each other by a bridge conductor to form a coplanar line on the input side and output side of each element, good grounding can be performed even at high frequencies of 1 GHz or higher. it can. Moreover, the coplanar line can determine the characteristic impedance of the line conductors on the input side and the output side of each element to eliminate the influence of the parasitic line. Therefore, the circuit design can be facilitated and the high frequency characteristics can be improved.

Further, in the microwave circuit of the second invention, a ground conductor is provided on the back surface side of the substrate, and the ground conductor is connected to the ground conductor on the front surface side of the substrate through the via hole to connect the line conductor and the substrate. Since the strip line is configured with the ground conductor on the back surface side, good grounding can be performed even at a high frequency of 1 GHz or higher. Moreover, the stripline can determine the characteristic impedance of the line conductors on the input side and the output side of each element to eliminate the influence of the parasitic line. Therefore, the circuit design can be facilitated and the high frequency characteristics can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a microwave circuit according to an embodiment of the first invention.

FIG. 2 is a diagram showing a structure of a microwave circuit according to an embodiment of the second invention.

FIG. 3 is a diagram showing characteristics of a two-stage low noise amplifier configured by the microwave circuit of the first invention.

FIG. 4 is a diagram showing a structure of a conventional microwave circuit.

[Explanation of symbols]

 1, 1a, 1b, 100 Ground conductor 2 Center conductor 3,13 Coplanar line 4 Spiral inductor 5 Capacitor 6 Line conductor 10 Transistor 11 Bridge conductor 12 Via hole 16 Microstrip line 20 Dielectric substrate 30 Input matching circuit 40 Series feedback Circuit 50 Output matching circuit (or interstage matching circuit)

Claims (2)

[Claims] 1. A ground conductor, which has a lumped constant line connected to a surface of a dielectric substrate by a linear line conductor and an active element, and surrounds the lumped constant line and the active element as one body around the substrate surface. In a microwave circuit in which a coplanar line is formed in a gap formed by dividing the ground conductor to perform input and output of the entire circuit, the ground conductor is provided from the peripheral portion of the substrate to the vicinity of both sides of each line conductor. Along with extending it, a strip-shaped bridge conductor is provided on each line conductor to connect the end portions of the ground conductor on the line conductor side to each other, and to the input side and output side of each lumped constant line and active element. A microwave circuit characterized by forming a coplanar line. 2. A ground conductor, which has a lumped constant line and an active element connected to a surface of a dielectric substrate by a linear line conductor, and surrounds the lumped constant line and the active element integrally around the substrate surface. In a microwave circuit in which a coplanar line is formed in a space where the ground conductor is divided to perform input and output of the entire circuit, a ground conductor is provided on the entire back surface of the substrate, and
The ground conductor is electrically connected to the ground conductor on the front surface side of the substrate through a via hole penetrating the board, and the line conductor and the ground conductor on the back surface side of the substrate connect the lumped constant lines and the input side of the active element. A microwave circuit having a strip line on the output side.