JPH02231801A - Microwave semiconductor phase shifter - Google Patents

Abstract

PURPOSE:To decrease the length of a diode loading line to 1/3 or less than the length of a conventional phase shifter by connecting a 1/4 wavelength impedance transformer used for setting quantity of phase shift in series in a main line, decreasing the length of the diode loading line and deciding the transformation ratio of the 1/4 wavelength impedance transformer in response to a required phase shift quantity. CONSTITUTION:A 1/4 wavelength impedance transformer 9 is connected in series with a main line 10. A diode loading line connecting to the 1/4 wavelength main line 10 is only a 1st line 4 and since the length of the 1st line 4 is 45 deg. or below, the length of the diode loading line is reduced to 1/3 or below more than the length of a conventional phase shifter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave semiconductor phase shifter, and particularly to a broadband semiconductor phase shifter.

[Conventional technology]

Figure 7 shows, for example, the Institute of Electronics, Information and Communication Engineers, technical report meeting material M.
W7B-43. PP. 35-42. 1 is a diagram showing a line configuration of a low-desode line type phase shifter, which is one of the microwave semiconductor phase shifters shown in 1978. In the figure,
2 is the main line, 2 is the 1/4 wavelength main line, 3 is the PIN diode, 4 is the first line, and 5 is the 1/4 wavelength impedance transformer. /4
The wavelength impedance transformer 5 will be collectively referred to as a diode-loaded line 6.

Next, the operation will be explained.

In this configuration, by switching the bias of the PIN diode 3, the load on the main line 1 can be changed to capacitive. By switching from inductive to inductive, the passage phase of the radio waves propagating through the main line 1 changes from delay to advance, and operates as a phase shifter.

Further, FIG. 8 is an equivalent circuit diagram for explaining the operation of the low-desode line type phase shifter shown in FIG. 7. 1/4 wavelength impedance transformer 5 in diode loaded line 6
is equivalently expressed by an ideal transformer 7 with a turns ratio of 1:N and a transformer line 8 with a length of 1/4 wavelength. The quarter-wavelength impedance transformer 5 has its characteristic impedance Z
If T, it is possible to match the characteristic impedance ZO with a line of characteristic impedance zT''/Zo.This characteristic impedance Z2 is defined as Zz=ZT
2/Zo.

Now, the impedance of the PIN diode 3 is expressed as ZF=0 Zi- j ωCj according to forward bias and reverse bias.

By switching the bias, the loaded line phase shifter is set so that the magnitude X+ of the line actance loaded on the main line 1 is set to the following value in accordance with the phase shift amount Δφ.

At the same time, in order to obtain matching in both bias states, 1
The characteristic impedance ZI of the /4 wavelength main line 2 is set as follows. Here, Zo is the characteristic impedance of the main line 1. In order to realize reactances with equal absolute values and opposite signs as shown in equation (1), in the conventional low-desode line phase shifter, the diode-loaded line 6 has a characteristic impedance Z2. The first line 4 and 1/ of length θ2
It consisted of a four-wavelength impedance transformer 5. The role of each line is as follows. Length θ2 of first line 4
are determined so that the absolute values of the reactances X2 are equal and have opposite signs in each bias state. That is, Here, θ2 becomes θ2<π/4. Next, the turns ratio N of the 1/4 wavelength impedance transformer 5 is set to a value that provides the required actance ±jXz. In other words, select. As a result, a loaded line type can be constructed in which the bias of the PIN diode 3 is switched between forward and reverse to obtain the required phase shift amount Δφ.

[Problem to be solved by the invention]

The conventional loaded line type phase shifter is configured as described above, so that the diode loaded line 6 is λ/4 to 3/4.
It has a length between 8 and λ. Because the line length is long, the required actance ±j at the design center frequency
Even if it was possible to obtain Xg, if the frequency moved away from the design center frequency, it would deviate significantly from the desired value, and as the phase shift amount deviated from the desired value, reflection would increase, and the phase shifter would exhibit narrow band characteristics. . In particular, this tendency becomes stronger when the phase shift amount is large; a phase shift amount of 90° makes the band too narrow, and a phase shift amount of 900° is not practical for conventional low-desode line phase shifters, and the limit is up to 45°. Therefore, a phase shift of 90° requires a configuration in which 456 phase shifts are connected in two stages, which increases the number of required diodes and increases the size of the device. Ta.

This invention was made to solve the above-mentioned problems, and it is possible to achieve a phase shift of 90° by using a loaded line type phase shifter to obtain broadband characteristics, and also to obtain broadband characteristics using a loaded line type phase shifter. The purpose is to obtain a microwave semiconductor phase shifter that takes advantage of its small size.

[Means to solve the problem]

The microwave semiconductor phase shifter according to the present invention eliminates the need for a quarter-wavelength impedance transformer included in the diode-loaded line, shortens the length of the diode-loaded line,
In addition, a new 1/4 wavelength impedance transformer is installed in series with the main line, and the transformation ratio of this impedance transformer is set according to the required amount of phase shift.

[Effect]

The microwave semiconductor phase shifter of the present invention shortens the length of the diode-loaded line by removing the 1/4 wavelength impedance transformer conventionally included in the diode-loaded line, and also adds a phase shift amount to the main line. Since a 1/4 wavelength transformer is provided and the transformation ratio is determined by the required amount of phase shift, the length of the diode-loaded line can be reduced to 1/3 or less of the conventional length. Therefore, the frequency change in the reactance exhibited by the diode-loaded line can be reduced, and the band of the rotary line phase shifter can be increased.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the line configuration of a microwave semiconductor phase shifter according to an embodiment of the present invention. In the figure, 10 is a 1/4 wavelength main line, and 9 is a 1/4 wavelength impedance transformer connected in series to the main line 10. As shown in the figure, the first line 4 is the only diode-loaded line connected to the 1/4 wavelength main line 10, and the length of the first line 4 is 45° or less. is less than 1/3 the length of the conventional one.

Next, the operation will be explained.

Fig. 2 is an equivalent circuit representation of the line configuration of Fig. 1 to explain the operation, and shows a 1/4 wavelength impedance transformer 9.
is shown using a transformer line 11 with a length of 1/4 wavelength and an ideal transformer 12 with a turns ratio of 1:N. A case will be described in which the reactance of the PIN diode 3 and the first line 4 seen from the connection point A between the loaded first line 4 and the 1/4 wavelength transformer 10 is ±jX2 as in the conventional case. That is, the length θ2 of the first line 4 and the characteristic impedance Z2 are both the same as before, and the length of the line loaded with the diode is set to 45°.
The following shall apply. At this time, in order to obtain the required phase shift amount Δφ, it is necessary to satisfy the relationship of equation (1).

That is, assuming that the impedance seen from point A in FIG. 2 toward the ideal transformer 12 side is 23, Z3 must have the following relationship for a given X2.

Further, as a condition for simultaneous matching in both bias states, the characteristic impedance Z4 of the 1/4 wavelength main line 10 is set as follows. Here, the transformation ratio N of the ideal transformer 12 to obtain Z3 that satisfies equation (5) is determined as follows. In this way, in order to obtain the required phase shift amount Δφ, the given
2, the phase shifter according to the present invention can be constructed by using the value of N shown in equation (7).

As an example, in the case of Δφ=906, the phase shift amounts of the phase shifter according to the present invention and the conventional loaded line type phase shifter are shown in FIGS. 3(a) and 3(b), respectively. Also, the forward bias of the phase shifter of the present invention and the conventional phase shifter. Figure 4(a) compares insertion loss and reflection (return loss) characteristics, which are other calculated characteristics when reverse bias is applied.
(b). and Figure 5(a). Shown in (b). As can be seen from these figures, the method of the present invention has lower phase shift and insertion loss than the conventional method. and reflection (return loss)
It can be seen that all of the characteristics can be made broadband.

In the above embodiment, a PIN diode is shown as the semiconductor, but a varactor diode, a field effect transistor, or the like may be used instead. In this case, the same effects as in the above embodiment can be obtained.

Further, in the above embodiment, the first line 4 is a line with a single track width, but as shown in FIG. You may also do this.

〔Effect of the invention〕

As described above, according to the present invention, the length of the diode-loaded line is shortened by connecting the quarter-wavelength impedance transformer used for setting the phase shift, which was conventionally included in the diode-loaded line, in series in the main line. Since the transformation ratio of the 1/4 wavelength impedance transformer is determined according to the required amount of phase shift, the length of the diode-loaded line can be shortened to 1/3 or less of the conventional length. Therefore, the frequency change in the reactance exhibited by the diode-loaded line can be reduced, and a broadband frequency characteristic can be obtained.

[Brief explanation of the drawing]

1 is a diagram showing a line configuration of a microwave semiconductor phase shifter according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the microwave semiconductor phase shifter of FIG. 1, and FIG. 3(a). (b) is a diagram showing the phase shift amount of a microwave semiconductor phase shifter according to the present invention and a conventional phase shifter, respectively, and FIGS. A diagram showing the insertion loss characteristics of a conventional phase shifter, Fig. 5(a), (
b) is a diagram showing return loss characteristics of a microwave semiconductor phase shifter according to the present invention and a conventional phase shifter, respectively, and FIG. 6 shows a line configuration of a microwave semiconductor phase shifter according to another embodiment of the present invention. 7 is a diagram showing a line configuration of a conventional microwave semiconductor phase shifter, and FIG. 8 is an equivalent circuit diagram of the microwave semiconductor phase shifter shown in FIG. In the figure, 1 is the main line, 3 is the PIN diode, 4 is the first line, 9 is the 1/4 wavelength impedance transformer, 1
0 is a 1/4 wavelength main line, l1 is a transformer line with a length of 1/4 wavelength, and 12 is an ideal transformer. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) Two first lines equipped with semiconductors at their tips are connected in parallel with the main lines separated by approximately 1/4 wavelength, and the passing phase of the main lines is changed by changing the bias applied to the semiconductors. , in a microwave semiconductor phase shifter that obtains a required amount of phase shift, the first line has a length of 1/4 wavelength or less, and at the connection point of the first line and the main line, each 1. A microwave semiconductor phase shifter, characterized in that a /4 wavelength impedance transformer is connected in series to a main line, and a transformation ratio of the impedance transformer is set according to a required phase shift amount.