JP2763031B2 - Phase inverter and push-pull power amplifier using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a phase inverter used to obtain two signals having a phase difference of 180 ° from one high-frequency signal. Four coupling circuits composed of four coupling lines are combined and connected in a ring shape, terminals are provided between the coupling circuits, and a signal input to an input terminal has a 180 ° phase difference between two output terminals. With a configuration to take out as a signal, and the type of the coupling circuit between the input terminal and one output terminal and the type of the coupling circuit between the input terminal and the other output terminal are different types such as open type-ground type, The other two coupling circuits are of the same type, such as an open-open type or a grounded-ground type, and the width of the line constituting the above-mentioned coupling circuit is determined by the input impedance of the output side circuit and Output impedance of input side circuit and A configuration that is set to down are impedance matching, also constitute a push-pull power amplifier using the phase inverter.

[Industrial applications]

The present invention relates to a phase inverter used to obtain two signals having a phase difference of 180 ° from one high-frequency signal.

As a phase inverter, a transformer using a coil or a phase modulator for a low frequency region using elements such as a capacitor and an inductance is known, but these circuits are used in an ultra high frequency region. Cannot be used due to stray capacitance. Therefore, it is necessary to use a distributed constant circuit such as a coupling line in the ultra-high frequency range.

[Conventional technology]

FIG. 7 is a plan view of a conventional phase inverter using a parallel coupling line. In this embodiment, ring-shaped transmission lines 2 and 3 are provided in combination on a printed circuit board 1 to form a λ / 4 parallel coupling line. The phase difference between terminals 4 ₁ , 4 ₂ , 4 ₃ and 4 ₄ is 90
Since DEG differ by the signal inputted from the terminal 4 ₁ will be signals having 180 ° phase difference is equally distributed to the terminal 4 ₂ and the terminal 4 ₄ are respectively output. In this case, the terminal
Although the 4 ₃ and a signal output from the terminal 4 ₂ are combined, since the output terminals 4 _2, 4 ₄ is 180 ° phase difference signal from the terminal 4 ₃ by the synthesis is not output.

The conventional example shown in FIG. 7 has a narrow usable band,
In order to solve this problem, the present applicant has previously filed Japanese Patent Application No. 1-84.
No. 95 (Title of Invention "Phase Inverter") was proposed. In this circuit, as shown in FIG. 8, four coupling circuits (10 ₁ to 10 ₄ ) composed of λ / 4 coupling lines are combined and connected in the form of a link to form coupling circuits 10 ₁ to 10 _4. Terminals 11 to 14 are provided between the two terminals, a signal which has entered the input terminal 11 is taken out as a signal having a phase difference of 180 ° between the two output terminals 12, 14, and no signal is output to the terminal 13, and the input terminal 11 and the coupling circuit 10 ₁ between the one output terminal 12 and, input terminal 11 and the other output terminal 14
Open the type of the coupling circuit 10 ₄ between the - ground type such different types, ₂ two other coupling circuits 10, 10 ₃ of the mold open - open or grounded - the ground type The same type is used. By adopting a configuration in which four coupling circuits are combined as described above, a wider band can be used than in the conventional example in which only two coupling circuits are combined.

[Problems to be solved by the invention]

By the way, when such a phase inverter is applied to, for example, a circuit in which the impedance level must be arbitrarily changed and set in order to obtain impedance matching between the input side circuit and the output side circuit, a conventional phase inverter is used. A circuit having a configuration in which a transformer is connected has been used. However, when such a transformer is used, when dealing with a wide band, the transformer has a multi-stage configuration, and the shape becomes large. Conversely, when the number of transformer stages is reduced and the size is reduced, the band used becomes narrower. There was a point.

An object of the present invention is to provide a phase inverter capable of arbitrarily setting an impedance level.

[Means for solving the problem]

FIG. 1 shows a principle diagram of the present invention. FIG. 1 (A) shows a phase inverter and FIG. 1 (B) shows a push-pull power amplifier using the phase inverter. In the figure, reference numerals 50 ₁ , 50 ₂ , 50 ₃ , and 50 ₄ denote coupling circuits each composed of a λ / 4 coupling line. , 52, 53, 54 are provided. 51 is an input terminal, 52 and 54 are output terminals,
The signal input to the input terminal 51 is sent to the two output terminals 52 and 54 for 180
。 A configuration in which a signal having a phase difference is extracted and no signal is output to the terminal 53 is adopted. In this case, the coupling circuit 51 ₁ between the one output terminal 52 and the input terminal 51, mold open the coupling circuit 50 ₄ between the input terminal 51 and the other output terminal 54 - such as ground type The different types and the types of the other two coupling circuits 50 ₂ and 50 ₃ are configured as the same type such as an open type-open type or a ground type-ground type.

In particular, the present invention has a structure that is set based on the desired impedance level width W _1, W ₂ of the lines constituting the coupling circuit 50 ₁ to 50 _4.

Further, according to the present invention, a push-pull power amplifier is configured using the phase inverter having the above-described configuration.

[Action]

The signal input to the input terminal 51 is output to the two output terminals 52 and 54.
Extracted as a signal with an 80 ° phase difference. Here, the coupling circuit 50 _1, 50 ₄ an open - the different types of ground type, coupling circuit 50 _2, 50 ₃ the open - open or grounded - the same type of ground type, such In this case, the configuration is such that four coupling circuits are combined, so that the usable band can be widened as compared with the conventional example in which only two coupling circuits are combined.

In addition, a desired impedance can be obtained by arbitrarily changing and setting the impedance in accordance with an impedance level at which a line width is desired to be obtained, and the phase inverter itself can have a function of a transformer.

Further, since the phase inverter operates as a transformer, by applying the phase inverter to a push-pull power amplifier, the number of stages of matching circuits before and after the amplifier can be reduced, and the device can be downsized.

〔Example〕

FIG. 2 is a plan view of a first embodiment of the present invention, and FIG. 3 is a plan view of a second embodiment of the present invention. In FIG. 2, 20 ₁ , 20 ₂ , 20
_3, 20 ₄ is coupled circuit constructed in lambda / 4 coupling line (2 lines configuration), 21 to 24 is a terminal provided between each coupling circuits 20 ₁ to 20 _4. The phase inversion of the signal is the same as that shown in FIG. One of the coupling circuits 20 ₁ to 20 ₄ next, as shown in FIG. 4 the draw schematically (A), one of the line width W ₁ and the other line width W ₂ is based on the desired impedance level Set to width. In other words, the λ / 4 coupling line can be equivalently replaced with an even mode impedance Zoo and an odd mode impedance Zoo, and the even mode impedance ZooL and the odd mode impedance ZooL of the wide line and the even mode impedance ZooH of the narrow line. The widths W ₁ and W ₂ are set so that the odd mode impedance ZooH matches the desired impedance levels Z _L and Z _H , respectively. In this case, a wide line has a lower impedance than a narrow line.

Similarly, in FIG. 3, reference numerals 25 ₁ , 25 ₂ , 25 ₃ , and 25 ₄ denote coupling circuits constituted by λ / 4 coupling lines (three-line configuration), and 26 to 29 denote coupling circuits 25 ₁ to 25 ₁ . a terminal provided between 25 _4. The state of the signal phase inverter is the same as that shown in FIG. One of the coupling circuits 25 ₁ to 25 ₄ next, as shown in FIG. 4 the draw schematically (B), the line width W _1, W _2, W ₃ is set to a width based on the desired impedance level Have been. In the three-line configuration, a larger tight coupling can be obtained since there are more portions (tightly-coupled portions) between the lines than in the two-line configuration. It is possible to change the impedance in a wider range than that of the configuration.

That is, according to the present invention, a desired impedance can be obtained by arbitrarily changing and setting according to the impedance to obtain the line width, and the phase inverter itself can have the function of a transformer. .

The phase inverter shown in FIG. 2 and FIG.
, The strip line configuration shown in FIG. 4B, and the coplanar wave guideline configuration shown in FIG. 4C. In FIG. 5, reference numeral 30 denotes a line constituting the phase inverter, and reference numeral 31 denotes a dielectric.

FIG. 6 shows a configuration diagram in which the second embodiment of the present invention is applied to a push-pull power amplifier. In the figure, reference numerals 35 and 36 denote phase inverters according to the second embodiment of the present invention, and matching circuits 37 ₁ , 37 ₂ ,
The FET 38, the matching circuits 39 ₁ , 39 ₂ , and the FET 40 are connected. R
The F input signal a is converted by a phase inverter 35 into signals b and 1 having a phase difference of 0 °.
A signal c having a phase difference of 80 ° is amplified by the FETs 38 and 40, respectively, supplied to the phase inverter 36, and combined to form the RF input signal a.
, A level-amplified RF output d can be obtained. The FETs 38 and 40 amplify only one polarity of the input signal for class B operation. In this case, the reference DC potential of the signal b and the signal c
In order to match the reference DC potentials of the above, the phase inverters 35 and 36 require a midpoint ground.

In this case, when an FET is used as the amplifier, the FET generally has a low input / output impedance (generally, 50Ω or less). Therefore, a matching circuit is required on the input / output side to obtain impedance matching with the transmission line on the input / output side. According to the present invention, since the impedance matching action can be provided here by setting the impedance level of the phase inverters 35 and 36, the number of L and C element stages forming the matching circuit can be reduced. That is, as shown in FIG. 9, a phase inverter (FIG. 8) 45,4
When using 6, the matching circuits 47 ₁ , 47 ₂ , 48 ₁ , 48 ₂ have L, C
In this embodiment, the matching circuits 37 ₁ , 37 having a small number of element stages must be used.
_2, 39 _1, 39 requires only ₂ can be miniaturized device.

〔The invention's effect〕

As described above, according to the present invention, it is possible to obtain two signals having a 180 ° phase difference in a wide band in an ultra-high frequency range. In this case, the width of the coupling line can be set based on a desired impedance level. It is not necessary to connect a transformer or the like. In particular, if the invention is applied to a push-pull power amplifier using an FET as an amplifier, the number of stages of matching circuits connected before and after the amplifier can be reduced, and the device can be downsized.

[Brief description of the drawings]

1 is a principle view of the present invention, FIG. 2 is a plan view of a first embodiment of the present invention, FIG. 3 is a plan view of a second embodiment of the present invention, and FIG. FIG. 5 is a diagram illustrating various transmission lines to which the present invention is applied, FIG. 6 is a configuration diagram in which the present invention is applied to a push-pull power amplifier, FIG. 7 is a plan view of a conventional phase inverter, FIG. 8 is a plan view of the phase inverter proposed earlier by the present applicant, and FIG. 9 is a configuration diagram in which the phase inverter shown in FIG. 7 is applied to a push-pull power amplifier. In the figure, 20 _{1 to} 20 ₄ , 25 _{1 to} 25 ₄ , 50 ₁ to 50 ₄ are coupling circuits, 21 to 24, 26 to 29, 51 to 54 are terminals, 35, 36, 55, 56 are phase inverters, 37 _1, 37 _2, 39 _1, 39 ₂ matching circuit, 38, 40 FET, 57, 58 denotes an amplifier.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-117503 (JP, A) JP-A-63-227201 (JP, A) JP-A-61-179602 (JP, A) JP-A-59-179 148405 (JP, a) JP flat 2-190003 (JP, a) JitsuHiraku Akira 62-24504 (JP, U) US Patent 4305043 (US, a) (58 ) investigated the field (Int.Cl. ^6, DB Name) H01P 5/10 H01P 5/16 H01P 5/22 H03F 3/60

Claims (2)

(57) [Claims] 1. A coupling circuit (50) comprising a λ / 4 coupling line.
₁₎ (50 ₂₎ (50 ₃₎ (50 ₄₎ connected four combination in a ring shape the respective coupling circuit (50 ₁ to 50 ₄₎ pin between (51, 52,
53, 54), and the signal input to the input terminal (51) is output to two output terminals (52, 5).
4) Take out the signal with 180 ° phase difference to the terminal (53)
Signal is not output to the input terminal (5
A coupling circuit (50 ₁ ) between 1) and one output terminal (52)
When, coupling circuit (50 ₄₎ the type of the open between the input terminal (51) and the other output terminal (54) - ground type such different types, the other two coupling circuits (50 _2, 50 ₃₎ mold open type - open or grounded - be constituted by the same type such as grounded, the width of the line constituting the coupling circuit _{(50 1 ~50 4) (W} 1,
A phase inverter characterized in that W ₂ ) is set to match the input impedance (ZL) of the output circuit and the output impedance (ZH) of the input circuit. 2. The phase inverter (55, 56) according to claim 1,
A push-pull power amplifier, characterized in that it is connected to each other via an amplifier (57, 58).