JP4849453B2 - Microwave power amplifier - Google Patents

Description

  The present invention relates to a microwave power amplifier mainly used in the VHF band, UHF band, microwave band and millimeter wave band.

  A conventional microwave power amplifier will be described with reference to FIGS. FIG. 13 is a diagram showing a configuration of a conventional microwave power amplifier (see, for example, Patent Document 1).

  Patent Document 1 shows a case where a two-stage impedance transformer composed of a microstrip line is used as an input / output matching circuit. Here, in order to simplify the description, a microstrip line is used as an input / output matching circuit. A case where a one-stage impedance transformer consisting of the above is used will be described. Furthermore, in Patent Document 1, there is only one slit, but here, a case where there are a plurality of slits will be described.

  In FIG. 13, a conventional microwave power amplifier includes an FET chip 2 composed of a plurality of field effect transistor (FET) cells 1, an input matching circuit 3 connected to the FET chip 2 with wires 15, and an FET. An output matching circuit 4 connected to the chip 2 by a wire 17 is provided.

  The input matching circuit 3 is provided with an input terminal 5 on the side opposite to the FET chip 2, and the output matching circuit 4 is provided with an output terminal 6 on the side opposite to the FET chip 2. The input matching circuit 3 and the output matching circuit 4 are made of microstrip lines formed on a dielectric substrate. Usually, the line length is ¼ wavelength in the used frequency band, and the line width of the input matching circuit 3 is such that the input impedance of the FET can be matched with the power supply impedance of the input terminal 5, and the output matching circuit. 4 is determined such that the output impedance of the FET matches the load impedance of the output terminal 6. Furthermore, the slits 12 are provided at equal intervals along the signal propagation direction in the output matching circuit 4, and sheet-like resistors 14 are loaded on the slits 12.

  Next, the operation of the conventional microwave power amplifier will be described. A signal input from the input terminal 5 is input to the FET chip 2 via the input matching circuit 3, and a signal amplified by the FET is output to the output terminal 6 via the output matching circuit 4. Since the output value of the amplifier depends on the gate width of the FET, that is, the number of FET cells, the FET chip 2 is composed of a plurality of FET cells 1 in order to realize a high output. At this time, as schematically shown in FIG. 13, a closed loop circuit may be formed by the FET cell 1, the input matching circuit 3, and the output matching circuit 4, and may oscillate. In this microwave power amplifier, the resistance 14 loaded in the slit 12 improves the isolation between the FET cells 1 and has the effect of suppressing oscillation. Further, by changing the length of the slit 12, it is possible to appropriately determine a frequency band that improves the isolation by changing the outer peripheral length of the closed loop circuit.

  As described above, in the conventional microwave power amplifier, the slit 12 is provided only for the purpose of improving the isolation in a desired frequency band by loading the resistor 14 and changing the outer peripheral length. Further, in order to improve the isolation between all the FET cells 1, the slits 12 are arranged at equal intervals according to the intervals of the FET cells 1.

  FIG. 14 is a diagram showing the configuration of another conventional microwave power amplifier (see, for example, Patent Document 2). In Patent Document 2, a single-stage impedance transformer is used for input / output matching, and a plurality of slits are provided along the propagation direction of the microwave. In FIG. 14, the slits are provided so that the path lengths of signals passing through the central portion and both end portions of the FET are substantially equal. As described above, in another conventional microwave power amplifier, a plurality of slits are provided for the purpose of reducing the phase deviation of the matching circuit. Although not described in the specification, as is clear from FIG. 14, the ratio between the central portion and the outer slit spacing was approximately 2: 1.

JP 2001-185966 A Japanese Patent Laid-Open No. 7-307626

  However, when a plurality of slits are arranged at equal intervals, the signal distribution deviation in the matching circuit increases, so that the non-uniform operation of the FET cell increases, and the gain and output decrease greatly. there were.

  Further, when the slit interval is determined only so as to reduce the phase deviation of the signal by the matching circuit, the improvement of the distribution amplitude deviation is not large, and there is a problem that the decrease of the gain and the output is also large.

  The present invention has been made to solve the above-described problems, and an object thereof is a microwave power amplifier capable of improving the gain and output by reducing the distribution deviation and achieving uniform operation of the FET cell. Is what you get.

The microwave power amplifier according to the present invention includes an FET chip composed of a plurality of FET cells, an input matching circuit connected to the input side of the FET chip, and an output matching connected to the output side of the FET chip A power amplifier comprising: a circuit, wherein at least one of the input matching circuit and the output matching circuit is connected to the FET chip, and a plurality of slits along the signal propagation direction on the FET chip side look including a first transmission line which is provided at different intervals, the width of the slit is a heterogeneous with respect to the propagation direction of the signal, it is wider in the vicinity of the center in the propagation direction of the signal of the slit This is a microwave power amplifier characterized by the following.

The microwave power amplifier according to the present invention includes an FET chip composed of a plurality of FET cells, an input matching circuit connected to the input side of the FET chip, and an output matching connected to the output side of the FET chip A power amplifier comprising: a circuit, wherein at least one of the input matching circuit and the output matching circuit is connected to the FET chip, and a plurality of slits along the signal propagation direction on the FET chip side Including the first transmission lines provided at different intervals, and the width of the slit is not uniform with respect to the signal propagation direction and is wide near the center of the slit in the signal propagation direction. since the microwave power amplifier, wherein, to reduce the distribution deviation effect that it is possible to improve the gain and output work to uniform operation of the FET cells Unlikely to.

Embodiment 1 FIG.
A microwave power amplifier according to Embodiment 1 of the present invention will be described with reference to FIG. 1 is a diagram showing a configuration of a microwave power amplifier according to Embodiment 1 of the present invention. In FIG. In the following, in each figure, the same reference numerals indicate the same or corresponding parts.

  In FIG. 1, the microwave power amplifier according to the first embodiment includes an FET chip 2 composed of a plurality of field effect transistor (FET) cells 1 and an input matching connected to the FET chip 2 by wires 15. A circuit 3 and an output matching circuit 4 connected to the FET chip 2 by a wire 17 are provided.

  The input matching circuit 3 includes a microstrip line 7 and a microstrip line 8 connected to the microstrip line 7 with a wire 16.

  The output matching circuit 4 includes a microstrip line 9 and a microstrip line 10 connected to the microstrip line 9 with a wire 18.

  The input matching circuit 3 and the output matching circuit 4 are made of microstrip lines formed on a dielectric substrate. Usually, the line length is ¼ wavelength in the frequency band used, and the line width of the input matching circuit 3 is such that the input side impedance of the FET can be matched with the power source impedance of the input terminal 5 and the output matching circuit. 4 is determined so that the output impedance of the FET can be matched with the load impedance of the output terminal 6.

  In addition, a plurality of slits 11 are provided at unequal intervals along the signal propagation direction in the microstrip line 7 of the input matching circuit 3. The slit 12 is the same as shown in FIG. Further, sheet-shaped resistors 13 and 14 are loaded in the slits 11 and 12, respectively.

  Here, a case where a two-stage impedance transformer is used is described, but the first-stage microstrip lines 7 and 9 connected to the FET chip 2 and the two connected to the input / output terminals 5 and 6 are described. The microstrip lines 8 and 10 at the stage are formed on different dielectric substrates in consideration of the line width that determines the characteristic impedance and the feasibility of the line length. Usually, the dielectric substrate forming the first stage microstrip lines 7 and 9 connected to the FET chip 2 is a high dielectric constant substrate and the second stage microstrip line 8 connected to the input / output terminals 5 and 6. 10 is formed of a substrate having a relatively low dielectric constant such as alumina.

  Next, the operation of the microwave power amplifier according to the first embodiment will be described with reference to the drawings.

  A signal input from the input terminal 5 is input to the FET chip 2 via the input matching circuit 3, and a signal amplified by the FET is output to the output terminal 6 via the output matching circuit 4. In a normal microstrip line, current concentrates at both ends from the center in the line width direction. However, since the slits 11 and 12 are arranged at unequal intervals on the microstrip lines 7 and 9, the magnitude of the current is small. Distributed. Further, the impedance of the FET cell 1 expecting a matching circuit varies depending on the slit interval.

  Therefore, by designing with the slit interval as a parameter, it is possible to reduce the non-uniformity of the amplitude distribution of the current that is larger at both ends than the center in the line width direction, that is, the signal distribution deviation and to match each FET cell 1 differently. There is an effect that it can be operated under conditions.

  Here, the configuration in which the resistors 13 and 14 are loaded in the slits 11 and 12 is shown, but it is not necessary from the viewpoint of reducing the signal distribution deviation.

  Moreover, although the case where a two-stage impedance transformer was used was shown, it may be one stage or three or more stages.

  Further, the slit may be provided only in the input matching circuit 3, only in the output matching circuit 4, or in both matching circuits. Providing in the input matching circuit 3 is effective in improving gain, and providing it in the output matching circuit 4 is effective in improving gain and output.

  In addition, although the case where a microstrip line is used has been described here, a transmission line having a conductor pattern and capable of being loaded with a slit, such as a triplate line or a coplanar line, has the same effect.

Embodiment 2. FIG.
A microwave power amplifier according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a diagram showing a configuration of the FET chip of the microwave power amplifier according to Embodiment 2 of the present invention and the first-stage microstrip line of the output matching circuit. FIG. 2 shows only the FET chip and the output matching circuit portion for the sake of simplicity.

  2, the same reference numerals 1, 2, 9, 12, 14, and 17 as those in FIG. 1 are the same as those in FIG.

  The intervals W1, W2, and W3 of the slits 12 are wider at the center and narrower at both ends in the width direction of the microstrip line 9. That is, in FIG. 2, the distance from the upper end of the microstrip line 9 to the first slit 12 counted from above is W1, the distance from the first slit 12 to the second slit 12 is W2, and the second slit. When the interval from the 12th to the third slit 12 is W3, the interval from the third slit 12 to the fourth slit 12 is W2, and the interval from the fourth slit 12 to the lower end of the microstrip line 9 is W1. W1 <W2 <W3.

  The second embodiment also has the same effect as the first embodiment. Further, in a normal microstrip line, current concentrates at both ends from the center in the line width direction, but the interval between the slits 12 is wider at the center and narrower at both ends in the width direction of the microstrip line. The magnitude of the current decreases at both ends and increases at the center. For this reason, the signal distribution deviation is reduced.

  3 and 4 are graphs showing the input matching circuit and its distribution characteristics when there are two slits. FIGS. 3A and 3B also show lines corresponding to ports 1 (Port 1) to 5 (Port 5) loaded for convenience in calculation, but the reference plane of the calculation result is the port And the connection surface of the matching circuit, and the calculation result corresponds to the characteristic of the matching circuit only. For example, a transmission line (microstrip line) 7 having a width of 0.308 mm and a length of 0.6 mm is formed on a substrate having a thickness of 0.1 mm and a relative dielectric constant of 12.9, and two slits 11 having a width of 0.01 mm are formed. When the main loading is performed, as shown in FIG. 3A, the slit interval W2 in the central portion is 0.144 mm (the ratio between the central portion and the outer slit interval is 2: 1), as compared with FIG. As shown in FIG. 4, when the slit interval W2 is 0.18 mm, as shown in FIGS. 4A and 4B, the amplitude deviation and phase deviation of the S parameter from the frequency FL (GHz) to FH (GHz) are obtained. Both have been improved. 4A and 4B, S41 indicates the amplitude and phase of the S parameter between port 4 and port 1, and S31 indicates the amplitude and phase of the S parameter between port 3 and port 1. . Here, the amplitude deviation indicates the difference in amplitude between S31 and S41, and the phase deviation indicates the difference in phase between S31 and S41.

  Further, the impedance of the FET cell 1 from which the output matching circuit 4 is expected becomes high impedance at both ends and low impedance at the center according to the interval between the slits 12, that is, the line width divided by the slit 12. FIG. 5 is a graph showing the impedance of the input matching circuit shown in FIG. The frequency characteristics from frequency FL (low) to FH (high) are plotted. Comparing the impedance (S44) in which the circuit side is expected from the outer distribution terminal, the case where W2 = 0.18 mm (□ mark) is compared to the case where the slit interval W2 at the center is 0.144 mm (circle mark). Has a higher impedance. In general, the impedance for efficiency matching is higher than the impedance for output matching. Therefore, there is an effect that the output value of each FET cell 1 becomes uniform by approaching efficiency matching at both ends where the signal amplitude is larger than the center, and approaching output matching at the center. Further, when a bias can be individually applied to each FET cell, there is an effect that the output value of each FET cell can be made more uniform by changing the bias condition between the central and outer FET cells.

Embodiment 3 FIG.
A microwave power amplifier according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 6 is a diagram showing the configuration of the microwave power amplifier according to the third embodiment of the present invention.

  In FIG. 6, reference numerals 1 to 18 are the same as those in FIG. Here, two slits 11 and 12 are shown. The protrusions 19 and 20 are provided on the FET chip side of the first-stage microstrip lines 7 and 9 connected to the FET chip 2. By providing the protrusions 19 and 20, the line widths of the microstrip lines 7 and 9 are increased in accordance with the width of the FET chip 2.

  The third embodiment also has the same effect as the first embodiment. Further, when a microstrip line having a uniform line width that matches the width of the FET chip 2 is used, the characteristic impedance is determined by the line width. In the third embodiment, the characteristic impedance is set to a desired value. The gate width of the FET can be increased while maintaining the value, and the output can be increased.

Embodiment 4 FIG.
A microwave power amplifier according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 7 is a diagram showing the configuration of the microwave power amplifier according to the fourth embodiment of the present invention.

  In FIG. 7, reference numerals 1 to 20 are the same as those in FIG. The cut portions 21 and 22 are provided on the opposite side of the first-stage microstrip lines 7 and 9 connected to the FET chip 2 from the FET chip 2. By providing the cut portions 21 and 22, the line width is matched to the line width of the second-stage microstrip lines 8 and 10.

  The fourth embodiment also has the same effect as the first embodiment. Further, the line widths of the first-stage microstrip lines 7 and 9 and the second-stage microstrip lines 8 and 10 are made uniform by the cut portions 21 and 22 at the connection parts, thereby reducing reflection due to discontinuity between the lines. In addition, since the path length of the signal propagating through both ends in the line width direction is shortened compared to the case where no cut is made, the difference from the path length of the signal propagating through the central portion is reduced, and the synthesis efficiency is improved. In addition, the gain and output are also improved.

  Further, by reducing the line width at one end of the microstrip lines 7 and 9 by the cut portions 21 and 22, the gate width of the FET is increased to improve the output, and the microstrip connected to the FET chip 2 is used. There is also an effect that a change in characteristic impedance caused by increasing the line width at one end of the lines 7 and 9 can be reduced, and a desired characteristic impedance can be realized.

Embodiment 5 FIG.
A microwave power amplifier according to Embodiment 5 of the present invention will be described with reference to FIG. FIG. 8 is a diagram showing the configuration of the first-stage microstrip line of the output matching circuit of the microwave power amplifier according to the fifth embodiment of the present invention. FIG. 8 shows only the first microstrip line of the output matching circuit for the sake of simplicity.

  8, reference numerals 9, 12, 14, 20, and 22 are the same as those in FIG. The discontinuous portion 23 is provided in the width of the slit 12. FIG. 8 schematically shows signal propagation.

  The fifth embodiment also has the same effect as the first embodiment. Further, as shown in FIG. 8, by providing discontinuous portions 23 in the width of the slit 12 with respect to the signal propagation direction, the path length of the signal propagating at both ends in the line width direction and the center portion are reduced. The difference from the path length of the propagating signal is reduced, the synthesis efficiency is improved, and the gain and output are improved.

Embodiment 6 FIG.
A microwave power amplifier according to Embodiment 6 of the present invention will be described with reference to FIG. FIG. 9 is a diagram showing the configuration of the first-stage microstrip line of the output matching circuit of the microwave power amplifier according to the sixth embodiment of the present invention. FIG. 9 shows only the first microstrip line of the output matching circuit for the sake of simplicity.

  9, reference numerals 9, 12, 14, 20, and 22 are the same as those in FIG. Further, the discontinuous portion 24 is provided in the line width portion of the microstrip line 9.

  The sixth embodiment also has the same effect as the first embodiment. Further, by partially reducing the line width, the degree of freedom in design can be increased, and both end portions in the width direction of the microstrip line 9 can be made to have higher impedance. Therefore, there is an effect that the amplitude of the signal is made more uniform, and the gain and output are further improved.

Embodiment 7 FIG.
A microwave power amplifier according to Embodiment 7 of the present invention will be described with reference to FIG. FIG. 10 is a diagram showing the configuration of the microwave power amplifier according to the seventh embodiment of the present invention.

  10, reference numerals 1 to 22 are the same as those in FIG. The input matching circuit 3 or the output matching circuit 4 is composed of a two-stage impedance transformer, and a corner of one end of the first-stage microstrip lines 7 and 9 connected to the FET chip 2 opposite to the FET chip 2 is Only one side is cut so as to be substantially the same as the line width of the second-stage microstrip lines 8 and 10. FIG. 10 also schematically shows signal propagation.

  The seventh embodiment has the same effect as the first embodiment. Also, as shown in FIG. 10, the difference in signal path length between both ends in the line width direction from the first-stage microstrip line 9 to the second-stage microstrip line 10 is reduced. The efficiency is improved and the reflection due to the discontinuity between the first and second microstrip lines is reduced, and the gain and output are improved.

Embodiment 8 FIG.
A microwave power amplifier according to Embodiment 8 of the present invention will be described with reference to FIG. FIG. 11 is a diagram showing a configuration of the microwave power amplifier according to the eighth embodiment of the present invention.

  In FIG. 11, reference numerals 1 to 22 are the same as those in FIG. The input matching circuit 3 or the output matching circuit 4 is composed of a two-stage impedance transformer, and the shapes of the slits 11 and 12 provided in the first-stage microstrip lines 7 and 9 connected to the FET chip 2 are as follows: A non-uniform, that is, discontinuous portion 23 is provided in the line width direction of the microstrip lines 7 and 9. In other words, the width of the slits 11 and 12 is wider near the center in the signal propagation direction of the slits 11 and 12. Signal propagation is also shown schematically.

  The eighth embodiment has the same effect as that of the first embodiment. Also, as shown in FIG. 11, the difference in signal path length between both ends in the line width direction from the first-stage microstrip line 9 to the second-stage microstrip line 10 is reduced. As a result, reflection due to discontinuity between the first and second microstrip lines is reduced, and the gain and output are improved.

Embodiment 9 FIG.
A microwave power amplifier according to Embodiment 9 of the present invention will be described with reference to FIG. FIG. 12 is a diagram showing the configuration of the microwave power amplifier according to the ninth embodiment of the present invention.

  12, reference numerals 1 to 22 are the same as those in FIG. 7, and reference numeral 24 is the same as FIG. The input matching circuit 3 or the output matching circuit 4 is composed of a two-stage impedance transformer, and the line widths of the first-stage microstrip lines 7 and 9 connected to the FET chip 2 are not relative to the center of the line. It is uniform, that is, it is narrow near the center in the signal propagation direction of the microstrip lines 7 and 9. Signal propagation is also shown schematically.

  The ninth embodiment also has the same effect as the first embodiment. Also, as shown in FIG. 12, the difference in signal path length between both ends in the line width direction from the first-stage microstrip line 9 to the second-stage microstrip line 10 is reduced. The efficiency is improved and the reflection due to the discontinuity between the first and second microstrip lines is reduced, and the gain and output are improved.

It is a figure which shows the structure of the microwave power amplifier which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the FET chip | tip of the microwave power amplifier which concerns on Embodiment 2 of this invention, and the 1st stage | paragraph microstrip line of an output matching circuit. It is a figure which shows the structure of the input matching circuit in case there are two slits. It is a graph which shows the distribution characteristic of the input matching circuit in case there are two slits. FIG. 4 is a graph showing the impedance of the input matching circuit of FIG. It is a figure which shows the structure of the microwave power amplifier which concerns on Embodiment 3 of this invention. It is a figure which shows the structure of the microwave power amplifier which concerns on Embodiment 4 of this invention. It is a figure which shows the structure of the 1st step | paragraph microstrip line of the output matching circuit of the microwave power amplifier concerning Embodiment 5 of this invention. It is a figure which shows the structure of the 1st step | paragraph microstrip line of the output matching circuit of the microwave power amplifier which concerns on Embodiment 6 of this invention. It is a figure which shows the structure of the microwave power amplifier which concerns on Embodiment 7 of this invention. It is a figure which shows the structure of the microwave power amplifier which concerns on Embodiment 8 of this invention. It is a figure which shows the structure of the microwave power amplifier which concerns on Embodiment 9 of this invention. It is a figure which shows the structure of the conventional microwave power amplifier. It is a figure which shows the structure of another conventional microwave power amplifier.

Explanation of symbols

  1 FET cell, 2 FET chip, 3 input matching circuit, 4 output matching circuit, 5 input terminal, 6 output terminal, 7 microstrip line, 8 microstrip line, 9 microstrip line, 10 microstrip line, 11 slit, 12 Slit, 13 Resistance, 14 Resistance, 15 Wire, 16 Wire, 17 Wire, 18 Wire, 19 Protrusion, 20 Protrusion, 21 Cut, 22 Cut, 23 Discontinuous, 24 Discontinuous.

Claims (7)

A microwave power amplifier comprising a FET chip composed of a plurality of FET cells, an input matching circuit connected to the input side of the FET chip, and an output matching circuit connected to the output side of the FET chip There,
At least one of the input matching circuit and the output matching circuit is
Connected to said FET chips, saw including a first transmission line provided with a plurality of slits along the propagation direction of the signal to the FET chip side at different intervals,
2. The microwave power amplifier according to claim 1, wherein a width of the slit is not uniform with respect to a propagation direction of the signal, and is wide near a center in the propagation direction of the signal of the slit . A microwave power amplifier comprising a FET chip composed of a plurality of FET cells, an input matching circuit connected to the input side of the FET chip, and an output matching circuit connected to the output side of the FET chip There,
At least one of the input matching circuit and the output matching circuit is
Connected to said FET chips, saw including a first transmission line provided with a plurality of slits along the propagation direction of the signal to the FET chip side at different intervals,
A microwave power amplifier characterized in that a line width of the first transmission line is non-uniform with respect to a propagation direction of the signal and is narrow near a center in the propagation direction of the signal of the first transmission line. . 3. The microwave power according to claim 1, wherein the interval is narrower at both ends compared to a central portion in the width direction of the first transmission line that is orthogonal to the propagation direction of the signal. 4. amplifier. When the width of the FET chip is expanded, the first transmission line has a wider line width on the FET chip side than the opposite side of the FET chip according to the expanded width of the FET chip. The microwave power amplifier according to any one of claims 1 to 3 . At least one of the input matching circuit and the output matching circuit is
A second transmission line connected to the first transmission line;
In accordance with the line width of the second transmission line, said first transmission line to any one of claims 1 to 4 opposite corners of the FET chip is characterized in that it is cut A microwave power amplifier as described. The first transmission line is cut only in one of two corners on the opposite side of the FET chip so as to be substantially the same as the line width of the second transmission line. 5. The microwave power amplifier according to 5 . The microwave power amplifier according to any one of claims 1 to 6, wherein the first and second transmission lines are any one of a microstrip line, a triplate line, and a coplanar line.

Images