JP2000244209A - High frequency semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency semiconductor device which can reduce the chip area of a monolithic microwave integrated circuit. SOLUTION: In a high frequency semiconductor device where a monolithic microwave integrated circuit having a coplanar line is formed, two signal lines 136 and 137 are provided by leaving a prescribed interval and each end of the lines is mutually connected. Further, a ground conductor 100 is provided by leaving the prescribed interval so that it surrounds the outer side of the two signal lines 136 and 137. The two signal lines and the ground conductor thus obtained constitute a folded coplanar line 125. In the folded coplanar line 125, the characteristic impedance of the coplanar line having one straight signal line can be made to be almost equal and the ground conductor on one side of the signal line is omitted. Thus, the signal lines can be integrated with high density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency semiconductor device used for microwave / millimeter wave communication, and more particularly to a monolithic microwave integrated circuit having a coplanar line.
(MMIC (monolithic microwave integrated circui
The present invention relates to a high-frequency semiconductor device on which t)) is formed.

[0002]

2. Description of the Related Art Conventionally, as a high-frequency semiconductor device, there is a semiconductor device in which a monolithic microwave integrated circuit having a coplanar line is formed. The coplanar line of this monolithic microwave integrated circuit is characterized in that the signal line and the ground conductor are on the same plane, so that no via hole is required and the element is easily grounded. In addition, since the characteristic impedance of the coplanar line is determined by the width of the signal line and the distance between the signal line and the ground conductor, the line width and the characteristic impedance can be set relatively freely regardless of the thickness of the semiconductor substrate. It is.

In order to increase the degree of integration of the monolithic microwave integrated circuit and reduce the chip area, it is necessary to bend a long line such as a quarter-wave line in a meander shape to integrate the line. The method of bending the coplanar line is disclosed in Japanese Patent Application Laid-Open No. Hei 1-188804. In JP-A-1-198804, FIG.
As shown in FIG. 1, a coplanar line 3 bent in a meandering shape is formed on a semiconductor substrate 1, and ground conductors on both sides of the signal line are connected by air bridges 4 at the position where the coplanar line 3 is bent. By setting the potential, unnecessary slot modes are suppressed.

[0004]

However, in the high-frequency semiconductor device on which the monolithic microwave integrated circuit having the coplanar line is formed, when the coplanar line is bent in a meander shape, the ground conductor becomes extremely thin. Therefore, it is necessary to secure a certain area of the ground conductor between the signal lines. Further, when the area of the ground conductor between the signal lines is secured to some extent, the proportion occupied by the coplanar line on the monolithic microwave integrated circuit increases, which hinders high integration.

An object of the present invention is to provide a high-frequency semiconductor device capable of reducing the chip area of a monolithic microwave integrated circuit.

[0006]

According to a first aspect of the present invention, there is provided a high-frequency semiconductor device having a monolithic microwave integrated circuit having a coplanar line formed at a predetermined interval. A folded type formed of two signal lines provided substantially parallel to each other and having one end connected to each other, and a ground conductor provided at a predetermined interval so as to surround the outside of the two signal lines. It is characterized by having a coplanar line.

According to the high frequency semiconductor device of the first aspect, two signal lines which are provided substantially in parallel at a predetermined interval and whose one ends are connected to each other, and are provided outside the two signal lines. In a folded coplanar line composed of ground conductors provided at predetermined intervals, an odd mode is predominant in the transmission mode, and an electric wall is formed at the center between two signal lines. Therefore, the center between the two signal lines is zero in potential and is equivalently grounded, so that the ground conductor on one side of the signal line can be omitted, and the signal lines can be highly integrated. As a result, the chip area of the monolithic microwave integrated circuit can be reduced. Therefore, the high-frequency semiconductor device can be downsized.

Further, the high-frequency semiconductor device of claim 2 is
2. The high frequency semiconductor device according to claim 1, wherein an interval between the two signal lines of the folded coplanar line and the ground conductor is set to a half of an interval between the two signal lines.

According to the high frequency semiconductor device of the second aspect, the distance between the two signal lines and the ground conductor is set to １ ／ of the distance between the two signal lines, so that the two signal lines are separated. Since it behaves as if there is a ground conductor with a space between the lines, it is equivalent to having a ground conductor with the same space on both sides of each signal line, and it is monolithic while maintaining the characteristic impedance of the coplanar line The chip area of the microwave integrated circuit can be reduced.

Further, the high-frequency semiconductor device of claim 3 is
3. The high-frequency semiconductor device according to claim 2, wherein MIM (Metal Insulator Metal) capacitors are inserted between the other ends of the two signal lines of the folded coplanar line and a ground conductor. It is characterized by.

According to the third aspect of the present invention, there is provided a semiconductor device for a high frequency between the other end of the two signal lines and the ground conductor.
By inserting each of the M capacitors, the same function as a transmission line having an electrical length of 90 ° with respect to a specific frequency can be realized with a smaller area.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high-frequency semiconductor device according to the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 shows an MMIC (Monolithic Microwave) as an amplifier according to a first embodiment of the present invention.
(Integrated Circuit: monolithic microwave integrated circuit)
Shows a high-frequency semiconductor device on which is formed. In addition,
In FIG. 1, a shaded portion represents a ground conductor. This high-frequency semiconductor device has an input port 101 and a DC blocking M
IM capacitors 102 and 103 and series MI for matching circuit
M capacitor 104, transistor 105, coplanar line 106, air bridges 107, 108, 126
, Resistor 109, and series MIM capacitor 1 for bypass
20, 121, DC bias terminals 122 and 123, an output port 124, and a folded coplanar line 125.

FIG. 2 shows an equivalent circuit of the high-frequency semiconductor device shown in FIG. As shown in FIG. 2, an input port 101 is connected to one end of a signal line 131, and the other end of the signal line 131 is connected to a DC blocking MIM capacitor 102.
To one end. One end of a signal line 132 is connected to the other end of the DC blocking MIM capacitor 102, and one end of a signal line 134 is connected to the other end of the signal line 132. Further, the series MIM capacitor 104 for the matching circuit is connected between the other end of the signal line 132 and the ground, and one end of the signal line 133 is connected to the other end of the signal line 132. A resistor 109 is connected between the other end of the signal line 133 and the DC bias terminal 122, and a bypass series MIM capacitor 120 is connected between the DC bias terminal 122 and the ground. The base of the transistor 105 is connected to the other end of the signal line 134, and the emitter of the transistor 105 is connected to ground. One end of the coplanar line 106 is connected to the collector of the transistor 105, and the signal line 13 is connected between the other end of the coplanar line 106 and the output port 124.
9. The DC blocking MIM capacitor 103 and the signal line 140 are connected in series from the coplanar line 106 side. Further, the other end of the coplanar line 106 and one end of the signal line 135 are connected, and the signal line 13 is connected.
5 is connected to one end of a signal line 136. One end of a signal line 137 parallel to the signal line 136 is connected to the other end of the signal line 136. The other end of the signal line 137 and the DC bias terminal 123 are connected via a signal line 138, and the DC bias terminal
Series MIM capacitor 12 between bypass 3 and ground
1 are connected.

As shown in FIG. 1, the two signal lines 1
A ground conductor 100 is provided so as to surround the outside of 36,137. A folded coplanar line 125 is constituted by the two signal lines 136 and 137 and the ground conductor 100. The distance between the signal lines 136 and 137 and the ground conductor is set to の of the distance between the two signal lines 136 and 137.

In the high frequency semiconductor device having the above structure,
As shown in FIGS. 1 and 2, a high frequency signal input from an input port 101 is applied to a DC blocking MIM capacitor 102.
Then, the signal is amplified by the transistor 105 through a matching circuit that functions with the matching circuit series MIM capacitor 104 and the like. The signal amplified by the transistor 105 is output from the output port 124 through a matching circuit functioning with the coplanar line 106, the folded coplanar line 125, the DC blocking MIM capacitor 103, and the like. The DC bias input to the DC bias terminals 122 and 123 is grounded at high frequency by the series MIM capacitors 120 and 121 for bypass, and is applied to the input / output terminals (base and collector) of the transistor 105.

Here, the folded coplanar line 1
Reference numeral 25 functions as a short stub, and is equivalent in circuit to a short stub formed by one coplanar line.

Further, the folded coplanar line 1
25 will be described in detail below.

In the folded coplanar line 125, an odd mode is dominant in the transmission mode, and an electric wall is formed at the center between the two signal lines 136 and 137.
Therefore, the center between the two signal lines 136 and 137 has zero potential and is equivalently grounded.

FIG. 6 is a sectional view of a coplanar line having one linear signal line, and FIG. 7 is a sectional view of a folded coplanar line of the high-frequency semiconductor device according to the present invention. As shown in FIG. 6, in the case of a coplanar line,
The width W of the signal line 404, the signal line 404, and the ground conductor 40
The characteristic impedance is determined by the distance G from the second (403). On the other hand, as shown in FIG. 7, in the folded coplanar line, the interval S between the two signal lines 408 and 409 is
By setting the distance G between the signal line 408 and the ground conductor 406 and twice the distance G between the signal line 409 and the ground conductor 407, it is as if there is a ground conductor at a distance G between the signal lines 408 and 409. Therefore, the characteristic impedance of the folded coplanar line becomes substantially equal to the characteristic impedance of the coplanar line having one linear signal line. As a result, the lines can be integrated at a high density while maintaining the characteristic impedance of the coplanar lines, so that the chip area of the monolithic microwave integrated circuit can be reduced.

For example, a 10 μm thick gallium arsenide substrate
When a coplanar line is formed with gold having a signal line width of 10 μm and a distance between the signal line and the ground conductor of 15 μm, the characteristic impedance becomes approximately 50Ω. FIGS. 8 and 9 show a folded coplanar connector in which two signal lines having a line width of 10 μm are spaced apart by 30 μm, a distance between the signal line and the ground conductor is set to 15 μm, and one ends of the two signal lines are connected to each other. The S21 and S11 characteristics of the line are shown respectively. FIG.
As shown in the figure, the input reflection loss is 20 dB or more, and the characteristic impedance can be regarded as approximately 50Ω.
This means that the folded coplanar line of the high-frequency semiconductor device of the present invention is equivalent in circuit to one coplanar line. Although the case where the characteristic impedance is 50Ω has been described here, the coplanar line having a single linear signal line can be replaced with a folded coplanar line in the same manner in the case of another characteristic impedance. is there.

As described above, by using the folded coplanar line 125 on the MMIC, the ground conductor on one side of the signal line can be omitted, and high integration can be achieved without impairing the performance.

(Second Embodiment) FIG. 3 shows a high frequency semiconductor device in which an MMIC of a frequency doubler according to a second embodiment of the present invention is formed. In FIG. 3, the hatched portions represent the ground conductors. The high frequency semiconductor device includes an input port 201 and a DC blocking MIM capacitor 20.
2,203 and series MIM capacitor 204 for matching circuit
, A transistor 205, a coplanar line 206,
Air bridges 207, 208, 209, a resistor 228,
Series MIM capacitors 220 and 221 for bypass, DC bias terminals 222 and 223, and output port 224
, A short stub 229, and a folded coplanar line 225.

FIG. 4 shows an equivalent circuit of the high-frequency semiconductor device shown in FIG. As shown in FIG. 4, one end of a signal line 231 is connected to an input port 201, and the other end of the signal line 231 is connected to a DC blocking MIM capacitor 202.
To one end. One end of a signal line 232 is connected to the other end of the DC blocking MIM capacitor 202, and one end of a signal line 234 is connected to the other end of the signal line 232. Further, a series MIM capacitor for matching circuit 204 is connected between the other end of the signal line 232 and the ground, and one end of the signal line 233 is connected to the other end of the signal line 232. A resistor 228 is connected between the other end of the signal line 233 and the DC bias terminal 222, and a bypass series MIM capacitor 220 is connected between the DC bias terminal 222 and the ground. The base of the transistor 205 is connected to the other end of the signal line 234, and the emitter of the transistor 205 is connected to the ground. One end of the coplanar line 206 is connected to the collector of the transistor 205, and the signal line 23 is connected between the other end of the coplanar line 206 and the output port 224.
8, signal line 239, DC blocking MIM capacitor 203
And the signal line 240 are connected in series from the coplanar line 206 side. Further, the above coplanar line 2
The other end of the signal line 236 is connected to one end of the signal line 235, and the other end of the signal line 235 is connected to one end of the signal line 236. Further, a series MIM capacitor 227 is connected between the other end of the signal line 235 and the ground. One end of a signal line 237 substantially parallel to the signal line 236 is connected to the other end of the signal line 236. Then, a series MIM capacitor 226 is connected between the other end of the signal line 237 and the ground. Further, the signal line 238,
A short stub 229 is connected between the connection point with the DC bias terminal 239 and the DC bias terminal 223, and a bypass series MIM capacitor 221 is connected between the DC bias terminal 223 and the ground.

As shown in FIG. 3, the two signal lines 2
A ground conductor 200 (shown in FIG. 3) is provided so as to surround the outside of 36,237. The above two signal lines 236, 237
Coplanar line 225 folded back by ground and ground conductor 200
Is composed. The distance between the signal lines 136, 137 and the ground conductor is set to one of the distances between the two signal lines 236, 237.
/ 2.

The functions of the folded coplanar line 225 and the MIM capacitors 226 and 227 will now be described with reference to FIGS.

A transmission line 301 having a characteristic impedance Z0 whose electric length is 90 ° with respect to a certain frequency f0 (FIG. 5A)
Is the electrical length θ ° and the characteristic impedance Z = Z0 / s
The transmission line 302 of inθ and the capacitors 303 and 304 of ωC = (1 / Z0) cosθ can be equivalently replaced (shown in FIG. 5B). A folded coplanar line 305 (shown in FIG. 5C) can be used instead of the transmission line 302, and the same performance as that of the original transmission line 301 can be equivalently and smaller. That is, the transmission line having the folded coplanar line 305 and the MIM capacitors 303 and 304 is equivalent to a transmission line having an electrical length of 90 ° and a characteristic impedance Z0 with respect to the frequency f0.

From the above relationship, in FIG. 3, the folded coplanar line 225 and the series MIM capacitor 22
6,227, the electrical length is 90 for a certain frequency f0.
° transmission line can be set to be equivalent,
It functions as an open stub having an electrical length of 90 ° with respect to the frequency f0.

In the high frequency semiconductor device having the above-described structure,
The high-frequency signal having the frequency f0 input from the input port 201 is input to the transistor 205 via the matching circuit functioning as the DC blocking MIM capacitor 202 and the matching circuit series MIM capacitor 204. The fundamental wave output from the transistor 205 is the coplanar line 2
06, folded coplanar line 225, MIM
90 ° equivalently composed of capacitors 226 and 227
The light is reflected again to the transistor 205 by the open stub. As a result, the transistor 205 is greatly distorted and outputs a second harmonic. The second harmonic is output from the output port 224 through a short stub 226, a matching circuit functioning with the DC blocking MIM capacitor 203, and the like. The DC bias is grounded in high frequency from DC bias terminals 222 and 223 by bypass series MIM capacitors 220 and 221 and applied to the input / output terminals (base and collector) of transistor 205.

As described above, by using the folded coplanar line 225 and the series MIM capacitors 226 and 227, the same function as a transmission line having an electrical length of 90 ° can be realized with a smaller area for a specific frequency. High integration can be achieved without deteriorating performance.

In the first and second embodiments, the MM
Although an amplifier and a frequency doubler have been described as ICs, the present invention is not limited thereto, and the present invention can be applied to all high-frequency semiconductor devices in which an MMIC having a coplanar line is formed.

In the second embodiment, the electric length 90
Although a frequency doubler has been described as a circuit using transmission lines of 90 °, a transmission line of 90 ° electrical length is also used in a bias supply circuit, an impedance converter, a branch line hybrid, and the like, and is used in all of those circuits. The present invention can be applied.

[0033]

As is apparent from the above description, the high frequency semiconductor device according to the first aspect of the present invention is a high frequency semiconductor device on which a monolithic microwave integrated circuit having a coplanar line is formed. Two signal lines which are provided in parallel and one end of which are connected to each other;
A folded coplanar line composed of ground conductors provided at predetermined intervals so as to surround the outside of the signal line.

Therefore, according to the high frequency semiconductor device of the first aspect of the present invention, the folded coplanar line 2
Since the center between these signal lines becomes zero potential and is equivalently grounded, it is possible to omit the ground conductor on one side of the signal line, so that the signal line is maintained while maintaining the characteristic impedance of the coplanar line. High-density integration can be achieved, and the chip area of a monolithic microwave integrated circuit can be reduced. Therefore, the high-frequency semiconductor device can be downsized.

According to a second aspect of the present invention, there is provided the high-frequency semiconductor device according to the first aspect, wherein the distance between the two signal lines of the folded coplanar line and the ground conductor is set to two signal lines. Is 1/2 of the interval of
It behaves as if there is a ground conductor at a distance between the signal lines of the book, so it is equivalent to the ground conductor being present at the same interval on both sides of each signal line,
The area of the monolithic microwave integrated circuit can be reduced while maintaining the characteristic impedance of the coplanar line.

According to a third aspect of the present invention, there is provided the high frequency semiconductor device according to the second aspect, wherein the MIM is provided between the other end of the two signal lines of the folded coplanar line and a ground conductor. Since each of the capacitors is inserted, the same function as a transmission line having an electrical length of 90 ° with respect to a specific frequency can be realized with a smaller area.

[Brief description of the drawings]

FIG. 1 is a plan view of a high-frequency semiconductor device according to a first embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of the high-frequency semiconductor device.

FIG. 3 is a plan view of a high-frequency semiconductor device according to a second embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of the high-frequency semiconductor device.

FIG. 5 is a diagram for supplementarily explaining the high-frequency semiconductor device.

FIG. 6 is a sectional view of a coplanar line.

FIG. 7 is a sectional view of a folded coplanar waveguide used in the high-frequency semiconductor device of the present invention.

FIG. 8 shows S21 of the folded coplanar line.
It is a figure showing a characteristic.

FIG. 9 shows S11 of the folded coplanar line.
It is a figure showing a characteristic.

FIG. 10 is a perspective view of a main part of a conventional high-frequency semiconductor device.

[Explanation of symbols]

101, 201: input port, 102, 103, 202, 203: DC blocking MIM capacitor, 104, 204: matching circuit series MIM capacitor, 105, 205: transistor, 106, 206: coplanar line, 107, 108, 126 , 207, 208, 209: air bridge, 109, 228: resistor, 120, 121, 220, 221: bypass series MIM
Capacitors, 122, 123, 222, 223 DC bias terminals, 124, 224 output ports, 125, 225 folded coplanar lines, 226, 227 series MIM capacitors, 229 short stubs, 301, 302, 306, 307 ... Transmission lines, 303,304 ... Capacitors, 305 ... Folded coplanar lines, 401,405 ... Semiconductor substrates, 402,403,406,407 ... Ground conductors, 404,408,409 ... Signal lines, 410 ... Electrical walls.

Claims (3)

[Claims] 1. A high-frequency semiconductor device on which a monolithic microwave integrated circuit having a coplanar line is formed, comprising: two signal lines which are provided substantially in parallel at a predetermined interval and one ends of which are connected to each other; A high-frequency semiconductor device having a folded coplanar line composed of ground conductors provided at predetermined intervals so as to surround the outside of two signal lines. 2. The high frequency semiconductor device according to claim 1, wherein a distance between the two signal lines of the folded coplanar line and the ground conductor is one of a distance between the two signal lines.
/ 2 for a high frequency semiconductor device. 3. The high-frequency semiconductor device according to claim 2, wherein MIM capacitors are respectively inserted between the other ends of the two signal lines of the folded coplanar line and a ground conductor. High frequency semiconductor device.