JPH03255703A - Phase inverter and push-pull power amplifier using the same - Google Patents

Abstract

PURPOSE:To provide the operation of a transformer for a phase inverter itself while obtaining a desired impedance by arbitrarily changing the width of a line corresponding to the desired impedance. CONSTITUTION:For the phase inverter composed of two lines, width W1 of one line and width W2 of the other line are set base on the desired impedance level. In such a case, the line with the wider width obtains the lower impedance rather than the line with the narrower width. Similarly, for the phase inverter composed of three lines, line width W1, W2 and W3 is set based on the desired impedance level. In comparison with the phase inverter composed of two lines, this phase inverter composed of three lines can obtain fine coupling more widely because there are more intervals between lines. Therefore, in comparison with the phase inverter composed of two lines, the impedance can be changed over a wider range.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a phase inverter used to obtain two signals with a phase difference of 180° from one high-frequency signal, and in particular, the purpose is to be able to arbitrarily set the impedance level. Four coupling circuits composed of four coupling lines are combined and connected in a ring shape, and a terminal is provided between each coupling circuit, and the signal that enters the input terminal is sent to two output terminals with a 180° phase difference. The configuration is such that the coupling circuit between the input terminal and one output terminal and the coupling circuit between the input terminal and the other output terminal are of different types such as an open type and a grounded type. The other two types of coupling circuits are open type-open type,
Alternatively, the width of the lines constituting the above-mentioned coupling circuit can be set based on the desired impedance level, and the push-pull power can be changed using this phase inverter. Configure the amplifier.

[Industrial application field]

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

Known phase inverters include transformers using coils and phase modulators for low frequency ranges using elements such as capacitors and inductances, but these circuits are difficult to use in ultra-high frequency ranges. Cannot be used due to stray capacitance. Therefore, in the ultra-high frequency region, it is necessary to use a distributed constant circuit such as a coupled line.

[Conventional technology]

FIG. 7 shows a plan view of a conventional phase inverter using parallel coupled lines. In this device, ring-shaped transmission line portions 2 and 3 are combined and provided on a printed circuit board 1 to form a λ/4 parallel coupled line. Terminal 4+, 42.43.44
Since the phase difference between the two terminals differs by 90', the signal input from the terminal 4I is equally distributed to the terminal 42 and the terminal 44, and signals having a 180° phase difference are outputted from each terminal. In this case, the signal output from the terminal 42 is combined with the terminal 43, but since the outputs of the terminals 42 and 44 have a 180° phase difference, no signal is output from the terminal 43 due to the combination.

Since the conventional example shown in FIG. 7 has a narrow usable band, in order to solve this problem, the present applicant previously applied
No. 95 (invention title: "Phase Inverter") was proposed. As shown in FIG. 8, four coupling circuits (101 to 104) composed of λ/4 coupled lines are connected in a link shape, and a terminal is connected between each coupling circuit 101 to 104.
~ 14 are provided, the signal entering the input terminal 11 is extracted as a signal with a 180° phase difference to the two output terminals 12 and 14, and the configuration is such that no signal is output to the terminal 13, and
Coupling circuit 1 between input terminal 11 and one output terminal 12
01 and the type of the coupling circuit 104 between the input terminal 11 and the other output terminal 14 is a different type, such as an open-grounded type, and the types of the other two coupling circuits 102 and 103 are set to an open type-open type. type, or the same type such as ground type-ground type. By combining four coupling circuits in this manner, a wider usable band can be obtained compared to the conventional example in which only two coupling circuits are combined.

[Problem to be solved by the invention]

By the way, when applying such a phase inverter to, for example, a circuit where the impedance level must be arbitrarily changed in order to achieve impedance matching between the input side circuit and the output side circuit, 1. Conventionally, a circuit has been used in which a transformer is connected to a phase inverter. However, when using such a transformer, when handling a wide band, the transformer has a multi-stage configuration and becomes large in size, and conversely, when the number of stages of the transformer is reduced to make it smaller, the usable band becomes narrower. There was a point.

An object of the present invention is to provide a phase inverter that can arbitrarily set an impedance level.

[Means to solve the problem]

FIG. 1 shows a diagram of the principle of the present invention, in which (A) shows a phase inverter, and (B) shows a push-pull power amplifier using a phase inverter. In the same figure, 501°502.503.50
Reference numeral ``i'' denotes a coupling circuit composed of λ/4 coupling lines, and four of these are combined and connected in a ring shape, and terminals 51.52° and 53.54 are provided between each coupling circuit. 51 is an input terminal, 52.54 is an output terminal, and the signal that enters the input terminal 51 is taken out as a signal with a 180° phase difference to the two output terminals 52.54, and no signal is output to the terminal 53. . In this case, the coupling circuit 511 between the input terminal 51 and one output terminal 52 and the coupling circuit 504 between the input terminal 51 and the other output terminal 54 are of an open type.
Other two coupling circuits 502.5 of different types, such as grounded type.
The type 03 is constructed of the same type, such as an open type-open type or a grounded type-grounded type.

In particular, the present invention provides widths W1 . The configuration is such that W2 is set based on a desired impedance level.

Further, the present invention configures a push-pull power amplifier using the phase inverter configured as described above.

Served. Here, the coupling circuits 501 and 504 are of different types of open type and grounded type, and the coupling circuits 502 and 503 are of the same type of open type and open type or grounded type and grounded type,
Since the configuration is such that four coupling circuits are combined, a wider usable band can be obtained compared to the conventional example in which only two coupling circuits are combined.

Further, by arbitrarily changing and setting the line width in accordance with the desired impedance level, a desired impedance can be obtained, and the phase inverter itself can have the function of a transformer.

Furthermore, since the phase inverter operates as a transformer, by applying it 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 made smaller.

[Effect]

The signal coming into input terminal 51 is sent to two output terminals 52.5.
[Embodiment] 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 Figure 2, 20+, 2
02.203.20a is a coupling circuit configured with a λ/4 coupling line (two line configuration), and 21 to 24 are terminals provided between each coupling circuit 201 to 204. The phase inversion of the signal is similar to that shown in FIG. A schematic diagram of one of the coupling circuits 201 to 20a is shown in FIG.
As shown in Δ), one line width W1 and the other line width W2 are set to widths based on a desired impedance level. In other words, the λ/4 coupled line can isometrically replace the even mode impedance Zoe and the odd mode impedance Zoo, and the even mode impedance ZoeL and odd mode impedance Z of the wide line can be
ooL, even mode impedance of narrow line 7 oe
The width W+ is such that the H and odd mode impedances ZooH match the desired impedance levels ZL and ZH, respectively.

Set W2. In this case, a wide line has a lower impedance than a narrow line.

Similarly, in Figure 3, 25+, 252.253.

254 is a coupling circuit composed of λ/4 coupled lines (three line configuration), and 26 to 29 are each coupling circuit 251 to 254.
This is a terminal provided between the terminals. The appearance of the signal phase inverter is similar to that shown in FIG. Coupling circuits 251-25
4 is schematically drawn as shown in FIG. 4(B), and the line widths W+, W2, and W3 are set to widths based on a desired impedance level. This 3
Compared to the two-line configuration, the main line configuration has more parts (tightly coupled areas) between the lines, so it is possible to obtain a larger tight coupling. It is possible to change the impedance over a wide range compared to other types.

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

The phase inverter shown in FIGS. 2 and 3 has a microstrip line configuration shown in FIG. 5 (A), a strip line configuration shown in FIG. It is also applicable to In addition, in FIG. 5, 30 is a line constituting a phase inverter, and 31 is 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 same figure, 35° and 36 are phase inverters of the second embodiment of the present invention, and a matching circuit 371 is installed between them.
．． ．． 372, FET38. and matching circuit 39+, 3
92, FET 40 is connected. RF input signal a
is O at the phase inverter 35.

A signal with a phase difference of 180 degrees and a signal C with a 180° phase difference are respectively amplified by FETs 38 and 40 and supplied to the phase inverter 36, and are combined and level-amplified with respect to the RF input signal a. You can get the sound. FET38.
Since the circuit 40 operates in class B, it amplifies only one polarity of the input signal. In this case, in order to match the reference DC potential of the signal S and the reference DC potential of the signal C, the phase inverters 35 and 36 require a midpoint ground.

In this case, if an FET is used as an amplifier, a matching circuit is required on the input/output side to achieve impedance matching with the transmission line on the input/output side since the FET generally has a low input/output impedance (generally less than 50Ω). However, in the present invention, by setting the impedance level of the phase inverters 35 and 36, it is possible to provide an impedance matching effect to the phase inverters 35 and 36. Therefore, it is possible to configure a matching circuit or to reduce the number of element stages of C. . That is, as shown in FIG. 9, the phase inverter (
(Figure 8) When using 45.46, this impedance level can only be uniform, so the matching circuit 47
+, 472.48+.

However, in the present invention, matching circuits 37+ and 372.39392 with a small number of element stages are sufficient, and the device can be made smaller.

[Effects of the Invention] As explained above, according to the present invention, two signals having a phase difference of 180° can be obtained over a wide band in the ultra-high frequency region, and in this case, the width of the coupled line can be adjusted to the desired impedance level. Since the settings can be made based on In particular, if 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 made smaller.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a plan view of the first embodiment of the invention, Fig. 3 is a plan view of the second embodiment of the invention, and Fig. 4 is a diagram explaining the line width. , FIG. 5 is a diagram explaining various transmission lines to which the present invention is applied, FIG. 6 is a block 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 a phase inverter previously proposed by the 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+~204.25+~254.501~504 are coupling circuits, 21~24.26~29.51~54 are terminals, and 35.3
6.55.56 is a phase inverter, 37+, 372.39
+, 392 is a matching circuit, 38.40 is a FET, and 57.58 is an amplifier.

Claims (2)

[Claims] (1) Coupling circuit (50
_1) (50_2) (50_3) (50_4) are combined and connected in a ring shape to form each coupling circuit (50_1 to 50_4).
Terminals (52, 52, 53, 54) are provided between the two output terminals (50_4), and the signal that enters the input terminal (51) is sent to the two output terminals (50_4).
2,54) is extracted as a signal with a 180° phase difference,
A configuration in which no signal is output to the terminal (53), and one coupling circuit (50_1) between the input terminal (51) and one output terminal (52), and one coupling circuit (50_1) between the input terminal (51) and the other output terminal (54) Coupling circuit (50_4)
and the type of the other two coupling circuits (50_2, 50_3) are different types such as open type-grounded type, open type-open type,
or of the same type, such as a grounded type and a grounded type, and is characterized in that the widths (W_1, W_2) of the lines constituting the coupling circuits (50_1 to 50_4) are set based on a desired impedance level. Phase inverter. (2) A push-pull power amplifier characterized in that it has a configuration in which two phase inverters (55, 56) according to claim 1 are connected via an amplifier (57, 58) between them.