JPH0652846B2 - Quadrature carrier phase adjustment circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a phase / amplitude modulation circuit, a demodulation circuit of the same modulated wave, or an image cancellation UP CONV. Circuit, such as 16QAM in a wireless communication device. The present invention relates to a phase adjustment circuit of a quadrature carrier wave demultiplexing circuit used in a DOWN CONV. Circuit or the like.

(Prior Art) Conventionally, in this type of circuit, as shown in FIG. 5, for each carrier wave demultiplexed by a 90-degree hybrid (hereinafter referred to as 90 ° HYB) 4, an electric line length converter 16 , 1
The phase adjustment function of 7 was added to secure the relative phase as a quadrature carrier. Fig. 6 shows an example in which open type phase adjusting stubs 16 'and 17' are added to the output terminals 14 and 15 of 90 ° HYB as a phase shift adjusting function for the stripline type 90 ° HYB element. The explanation is given below.

In FIG. 6, a two-stage 90 ° HYB4 is used to obtain a distributed wave of the carrier wave input from the input terminal 1 to the output terminals 2 and 3. At this time, in the vicinity of the designed center frequency of 90 ° HYB4, the output of the output terminal 2 has a phase delay of 90 ° with respect to the output of the output terminal 2.

(Problems to be solved by the invention) However, at a frequency away from the design center of 90 ° HYB, the relative phase of −90 ° cannot be maintained.

Specifically, the band in which the relative phase value of the distributed wave is within -90 ° ± 1 ° is 5 of the band in which the distributed wave amplitude deviation is within 1 dB.
You can only get about 0%. Moreover, the relative phase of the distributed wave of 90 ° HYB4 is easily affected by VSWR of the output terminals 2 and 3,
The -90 ° relative phase value is easily damaged.

For example, temporarily connect an isolator to the output terminals 2 and 3,
Even if the interference from the latter-stage circuit is suppressed, if the VSWR of the isolator itself is about 1.2, Return Loss is about 2
It is 1 dB. Also, VSWR at 90 ° HYB output is 1.5
If so, the second reflection (traveling wave) is −
35 dB, electrical length up to primary and secondary reflections is λ / 4
If, then the superposition is in the direction orthogonal to the main traveling wave. Therefore, the phase of output terminal 2 or 3 is It will change to some extent. A method of avoiding this change by geometrically symmetrically arranging the circuit can be considered, but it cannot be expected that the reflection modes of the isolator and the output terminals 2 and 3 can be obtained in the same manner.

For the above reasons, in the orthogonal carrier wave distribution circuit, the phase adjusting stubs 16 'and 17' shown in FIG. 6 are added for adjustment.
FIG. 6 shows an example in which an open stub with a width of 50 Ω is used for a 50 Ω line. In this case, assuming that the length is 1 and the width is w, an open stub of 1 / w = 1 has about 2 to about 2.
There is a 3 ° adjustment capability. Therefore, the relative phase shift variable range by the phase adjusting stubs 16 'and 17' of FIG. 6 is about ± 2 to 3 °.

However, in the case of a circuit as shown in Fig. 6, if a large adjustment is attempted (for example, VSWR from the latter stage at output terminals 2 and 3)
If it is bad, it is expected that a correction capability of 5 to 10 degrees will be required. ), The open stub becomes very long in the above method, and the output VSWR of the circuit deteriorates significantly.

Further, in order to adjust the open stub, it is necessary to use conductive paint or trim the pattern, which makes it difficult to deal with the frequency change of the carrier wave to be handled.

Furthermore, the level deviation of the distributed wave tends to be large, which impairs the symmetry of the circuit.

In the example of FIG. 6, a stripline type 90 ° HYB is shown, but if this is a 90 ° HYB by a waveguide, a mechanism such as a line stretcher is required as an electric line length converter, and adjustment is more difficult. It will be

As shown in the above example, in the method of adjusting the phase of each of the demultiplexed orthogonal waves, the operation of changing the electric line length is required, and it is difficult to change the line configuration and shape. is there.

(Means for Solving the Problems) In order to solve such a drawback, the present invention uses a fine carrier injection synthesis from an isolated end of a four-terminal 90 ° HYB that splits an orthogonal wave. , The minute carrier injected into the isolated end is obtained by adjusting the combined output of each of the two directional couplers connected in series at an interval of electrical length λ / 2 with a variable attenuator, and synthesizing them. The adjustment of the -90 ° relative phase with respect to the operation of HYB can be easily performed.

FIG. 1 is a block diagram showing a configuration example of the present invention, in which 1 is a carrier wave input terminal, 2 and 3 are orthogonal carrier wave output terminals, and 4 is a 9
0 ° HYB, 5 and 6 are directional couplers, 7 and 8 are variable attenuators, 9 is a combiner, 12 is a HYB input terminal, 13 is an isolation terminal, and 21 and 22 are coupling output terminals.

(Operation) FIG. 3 is a conceptual diagram showing the basic operation of the present invention, and FIG. 4 is a vector composition diagram for explaining its principle. That is, in the present invention, the two directional couplers 5 and 6 have a phase difference λ
Two small carrier waves (indicated by broken line arrows in FIGS. 3 (b) and 3 (c)) having // 2 are extracted, and the respective amplitudes are set to the required levels by the variable attenuators 7 and 8. Further, it is combined by the combiner 9, and this is injected from the 90 ° HYB isolation terminal 13 as a minute carrier for adjusting the relative phase of the distributed wave,
The adjustment is completed by the vector composition principle as shown in the figure.

In Fig. 3, (a) shows the operation near the design center of 90 ° HYB, and the amplitude-phase correlation of the input and output waves at that time is shown in polar coordinates in Fig. 4 (a). ). In the operation shown in FIG. 3B, only the minute carrier extracted by the first directional coupler 5 is selected by the variable attenuator 7,
This shows superimposition of a minute carrier on the output wave when it is input to the 90 ° HYB isolation terminal 13, and Fig. 4 (b) shows the phase change of the output wave at that time. Furthermore, Fig. 3
In the operation shown in (c), only the minute carrier extracted by the second directional coupler 6 is selected by the variable attenuator 8, and 90
This figure shows the superimposition of a minute carrier wave on the output wave when it is input to the isolation terminal 13 of the HYB4, and the phase change of the output wave at that time is shown in Fig. 4 (c).

As can be seen from the figure, by operating the two variable attenuators 7 and 8 in FIG. 1, the intermediate state between the state of FIG. 4 (b) and the state of (c) of FIG. Since it can be arbitrarily selected, the adjustment range from the state of FIG. 4 (b) to the state of (c) of FIG. 4 can be secured by the configuration shown in FIG.

(Embodiment) FIG. 2 shows a two-stage type 90 using a strip line according to the present invention.
It is a figure which shows one Example which applied (degree) HYB. In particular, FIG. 2 shows an example in which diodes 7'and 8'are used as the variable attenuators 7 and 8 of FIG. 1 and relative phase adjustment can be performed in both positive and negative directions.
In FIG. 2, 1, 2, ..., 5 are the same as those in FIG. 1, 7 ', 8'are diodes, 9 is a combiner, and 10 is λ /
4 electrical length line, 11 is 3λ / 4 electrical length line, 12 is HYB
Input end, 13 is an isolation end, 19 and 20 are termination dummies of the directional couplers 5 and 6, 21 and 22 are coupling output ends of the directional couplers 5 and 6, and 23 is a bias to the diodes 7'and 8 '. This is a bias terminal for applying a voltage.

The operation when the coupled output 90 ° HYB4 obtained by the first directional coupler 5 in FIG. 2 is input to the isolation terminal 13 corresponds to (B) in FIG. As shown in (b) of FIG. 4, the combined output obtained by the first directional coupler 5, that is, the minute carrier, is superimposed on the 90 ° HYB distribution output of the output terminals 2 and 3. Furthermore, when the combined output obtained by the second directional coupler 6 in FIG. 2 is input to the isolating end 13 of 90 ° HYB, the output terminals 2, 3 as shown in FIG. Of 9
The combined output obtained by the second directional coupler 6, that is, the minute carrier, is superimposed on the 0 ° HYB distribution output. In FIG. 2, the amplitude of the output of the directional coupler 5 or 6 is adjusted by the diode 7 or 8, and the respective components are combined by the combiner 9 and then the isolator is passed through the 3λ / 4 electrical length line 11 and then the isolator. The input is made to the rate end 13. Where 3λ
The reason for passing through the / 4 electrical length line 11 is that the phase relationship between the main carrier and the minute carrier to be combined is in the state described in FIG. Next, in FIG. 2, the superimposed wave input from the isolation end 13 of the 90 ° HYB4, that is, the minute carrier, may have a very small amplitude with respect to the main carrier. It can be seen from the vector composition diagram in (c).

For example, when it is desired to make the relative angle of the distributed wave 90 ° + 10 °, a negative DC voltage is applied to the bias terminal 23 of FIG. 2 and the diode 8'is forward biased to make the second directional coupler 6 Select the side and inject the combined output of tan (10 ° / 2). From this result, the coupling constant in the directional coupler 6 is also determined to be 20 log tan (10 ° / 2) ≈−21.2 (dB). Similarly, if you want to make 90 ° -10 °,
Applying a positive DC voltage to the bias terminal 23 in Fig. 2,
It suffices to bias the diode 7'in the forward direction and select it on the first directional coupler 5 side, and inject a coupled output of about tan (10 ° / 2).

Therefore, the coupling of the directional coupler 5 may be about −21.2 dB, which is equivalent to that of the second directional coupler 6. In FIG. 2, the diodes 7'and 8'are the directional couplers 5 and 5 as described above.
The combined output from each of 6 will be switched. By selecting the bias current value at this time, the combined ratio of the combined outputs of the directional couplers 5 and 6 can be changed. As a result, 90 ° HYB4 The relative phase value of the output from the output terminals 2 and 3 has a variable width of 90 ° ± 10 °.

In addition to the embodiment shown in FIG. 2 described above, the diodes 7'and 8'may be implemented by using other semiconductors such as FETs, and the diodes 7'and 8'just perform switching operation. Alternatively, the variable attenuators 7 and 8 can be inserted in series with the diodes 7'and 8 ', respectively. Of course, it is needless to say that the variable attenuators 7 and 8 can be used without the diode. Further, although the above-mentioned embodiment shows an example in which it is constituted by a strip line, it is needless to say that it can be constituted by a three-dimensional circuit such as a waveguide.

(Effects of the Invention) As described above, according to the present invention, adjustment control of the 90 ° HYB relative phase of distributed waves can be realized by a simple operation and without changing the element shape such as changing the electrical length. You can

In addition, the input condition is stable because the element shape is not changed,
Adjustment control is possible without damaging the basic characteristics of 0 ° HYB itself.
The wideband HYB characteristics will be maintained under any control environment, so that the 90 ° HYB design range can be fully utilized.

Further, as in the above example, the DC control can be performed, so that an external control system can be easily connected. For example, when the present invention is applied to an image cancellation type UP / DOWN CONV., An image with automatic optimization control in which a super image cancellation area that appears in a spot shape with respect to a normal carrier frequency area is selected each time the frequency is changed. Cancel CONV. Is possible.

According to the present invention, the above-mentioned simplification and rationalization can be achieved in the field of applying orthogonal carrier waves.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of the present invention, FIG. 2 is a diagram showing an embodiment according to the present invention, FIG. 3 is a conceptual diagram showing a basic operation of the present invention, and FIG. 4 is an operation of the present invention. FIG. 5 is a vector diagram for explaining the principle, FIG. 5 is a block diagram showing an example of a conventional quadrature carrier wave phase adjusting circuit, and FIG. 6 is a diagram showing an example using a conventional stripline. 1 …… input terminal, 2,3 …… output terminal, 4 …… 90 ° HY
B, 5, 6 ... Directional coupler, 7, 8 ... Variable attenuator,
9 ... Combiner, 12 ... HYB input end, 13 ... Isolation end.

Claims (1)

[Claims] 1. A quadrature carrier wave demultiplexing circuit using a 90-degree hybrid, and a first directional coupler connected to an input terminal, and 2 from the input end on the output side line of the first directional coupler. A second directional coupler connected to a point separated by one-half wavelength, the 90-degree hybrid having an input end connected to an output end of the second directional coupler, and the first directional coupler A first variable attenuator connected to a coupling output end of the second directional coupler, a second variable attenuator connected to a coupling output end of the second directional coupler, an output of the first variable attenuator and the first variable attenuator, And a line for injecting the output of the combiner with the output of the variable attenuator 2 into the isolation end by adjusting the phase with respect to the input end of the 90-degree hybrid. Quadrature carrier phase adjustment circuit characterized by making relative phase adjustable .