JPH09326640A - Slot line balanced modulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit of a balanced phase modulator of very high frequency concerning the circuit configuration of the balanced phase modulator using the slot line of microwaves/milliwaves formed on the ground conductor surface of a dielectric board. SOLUTION: In order to provide the modulated output of phase shift quantity 0-π at the output terminal of a line for synthesizing two lines branching an input signal into two parts, positions for mounting two diodes 2a and 2b for turning on/off the respective lines for synthesizing these two branched lines on the lines are set at positions mutually separated for a certain specified length different from the positions just after branching from a slot line 3 for input signal toward two slot lines 3a and 3b but circuit constituting means 3c and 3d are provided for producing a state equivalent with the state of short- circuiting/opening the input terminal of the slot line for a length λg/4 for synthetic output at the final section of two branched lines in the manner of high frequency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency transmission line of a distributed constant circuit formed by cutting a groove (slot) of a constant width on one side of a ground conductor surface of a dielectric substrate, and an effective wavelength λg input by a slot line. Conventionally, a pair of switch devices such as a diode is provided at each input end of a slot line having a length λg / 4 immediately after branching on a slot line that branches a high-frequency signal into two. Each of these is turned on / off by a low-frequency modulated signal with positive and negative polarities of the external input, so that the output end of the slot line of λg / 4 is opened / shorted, and the input high-frequency signal is output as a composite output. The present invention relates to a circuit configuration of a microwave / millimeter wave slot line balanced phase modulator that obtains a high frequency signal with a modulated output with a phase shift amount of 0-π.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional circuit configuration of a microwave / millimeter wave slot line balanced modulator. Dielectric substrate 1 with slot lines formed with its surface as the ground conductor surface 1
The microwave and millimeter-wave high-frequency signals input from the strip line 4 on the back surface (perspective) of the are electromagnetically coupled to the slot line 3 on the surface of the substrate that is positioned orthogonal to the strip line 4 and input from the slot line 3. Although it is branched as a slot line in the direction of two slot lines 3a, 3b that give a phase shift amount 0-π to a high frequency signal, conventionally, it is a slot line 3a, 3b of length λg / 4 immediately after branching into two. A pair of switching devices 2a and 2b such as diodes, which are in the opposite directions, are provided close to the branch point which is the input end of the switch, and the pair of switching devices 2a and 2b are turned on by the low frequency modulation signal of the external input. /
Turn off. From each switch device 2a, 2b, wavelength λ
There is an open (OFF) state (maximum impedance when voltage is maximum and current is minimum) that occurs at the output position of slot lines 3a and 3b with a length of λg / 4, that is, at a distance of λg / 4 that is a quarter of g. The output of the short-circuited (on) state (minimum impedance in the state of minimum voltage and maximum current) is combined, and the combined output is the high frequency of the modulated output that is phase-balanced and has a phase shift of 0-π with respect to the high frequency signal of the input. The signal is obtained. The two branched λg / 4-length slot lines 3a, 3b are electromagnetically coupled to the backside (transparent) stripline 4 positioned orthogonally to the portion to which the output ends are connected, and are transferred to the outside. It is output as a balanced modulation output signal with a phase amount of 0-π.

At this time, the pair of switch devices 2a, 2
b is given from the outside by a low-frequency modulated signal with positive and negative polarities so that if one is in the on state, the other is in the off state, the two high-frequency input signals are divided into two slots. Each length of the last part of the track λg /
If one of the output ends of each of the 4 slot lines 3a and 3b is in the open state, the other is short-circuited.A high frequency signal is obtained alternately, and as a result, a balanced phase with a phase shift of 0-π with respect to the input high frequency signal. The modulated output signal of the modulator is obtained.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the prior art, the high frequency signals input by the slot line 3 are provided at the input ends of the slot lines 3a, 3b each having a length λg / 4 immediately after branching into two. A pair of switching devices 2a and 2b are turned on / off in the direction, and the conventional balanced phase is used to combine two high-frequency signals with a phase difference of π between the output ends of the slot lines 3a and 3b of length λg / 4. As shown in the circuit configuration diagram of FIG. 5, the modulator has a mounting position of the pair of switch devices 2a, 2b close to the branch point immediately after the branch from the input slot line 3 to the two slot lines 3a, 3b. The outputs of the lines 3a and 3b, which are arranged close to each other and are separated by λg / 4, are combined and coupled to the output backside stripline 4 at the same time. However, the size of the switch devices 2a, 2b becomes so large that it cannot be ignored with respect to the length λg / 4 of each of the modulation slot lines 3a, 3b on the line that branches the input high frequency signal. In the case of the millimeter wave, it is impossible to actually arrange the switch devices 2a and 2b at the position immediately after the branch, and in reality, they are only arranged as close as possible to the branch point. As a result, the switch device 2a, 2 at its input end
When b is turned on / off, the output of the two slot lines 3a, 3b of each length λg / 4 whose output ends are in the open / short circuit state. The balanced phase modulator that obtains the modulated output signal with the correct phase shift amount of 0-π does not operate correctly, and the modulation characteristics of the balanced phase modulator with the phase shift amount of 0-π deteriorate. Will cause it.

An object of the present invention is to provide a pair of switch devices 2a and 2b for balanced phase modulation, which is a problem of the above-mentioned prior art.
The input signal is an ultra high frequency microwave / millimeter wave whose size is so large that it cannot be ignored with respect to the line length λg / 4 of each slot line 3a, 3b for modulation on the line that branches the input high frequency signal. Even if the switch device 2a, 2
The purpose of the present invention is to provide a circuit configuration of a balanced phase modulator using slot lines so that b can be actually provided and a modulated output having a correct phase shift amount of 0-π can be obtained as a combined output signal.

[0006]

To achieve this object, the basic configuration of the slot line balanced modulator of the present invention is the basic characteristics of a high frequency transmission line of a distributed constant circuit. (1) Voltage and current are the same on the line. The state (the short-circuited ON state and the open-circuited OFF state) occurs repeatedly every half wavelength λg / 2 λg / 2. (2) Focusing on the fact that an open (OFF) state and a short-circuit (ON) state alternate every λg / 4 of a quarter of the wavelength, and referring to the circuit configurations of FIG. 1 and FIG. Slot of length λg / 4 for composite output of each final part of two slot lines that split the high frequency signal of wavelength λg input by the slot line (3) formed on one side of the ground conductor surface of the substrate (1) line
Each of the pair of switch devices (2a, 2b) at each input terminal of (3a, 3b) is turned on / off by a low frequency modulation signal with positive / negative polarity of the external input, and the λg / 4 slot line (3a, In the slot line balanced modulator that obtains a modulated output with a phase shift amount of 0-π by synthesizing the output end of 3b) in the open / short circuit state, set the mounting position on the line of the pair of switch devices (2a, 2b). ,
By turning on / off the switch devices (2a, 2b) at positions separated from each other by a certain length from a branch point of a slot line that branches the input high frequency signal into two, Circuit means (3c, 3d in the example of FIG. 1 and 8a, 8b in the example of FIG. 2 to make the output ends of the slot lines (3a, 3b) of each length λg / 4 open / short-circuited at high frequency. )
Is provided.

According to this circuit configuration of the present invention, two slot lines each having a length λg / 4 immediately after the branch point where the high frequency input signal is branched into two slot lines from the slot line 3
Unlike the branch points at the input ends of 3a and 3b, the switch devices 2a and 2b are mounted and arranged at positions where they can be actually installed sufficiently apart from each other by adding a line of a specific length from the branch points. Specifically, the input ends of the slot lines 3a, 3b of each length λg / 4 for modulation and synthesis of the output parts on the two branched lines are turned on / off and the output ends of the slot lines 3a, 3b are changed. Since an equivalent state is created when opened / shorted, two switches are used in the slot line balanced modulator circuit when an input signal is a microwave / millimeter wave ultra-high frequency signal with a short signal wavelength λg. Realize a microwave / millimeter wave slot line balanced modulator that can actually be equipped with devices 2a and 2b, and that can obtain a modulated output with a correct phase shift amount of 0-π with respect to the input high frequency signal. You will be able to.

[0008]

1 is an external view showing a circuit configuration of a slot line balanced modulator of an embodiment corresponding to claim 2 of the present invention. FIG. 1 (a) is a surface of a dielectric substrate 1. 2B is a plan view of the B surface of FIG. 3B when viewed from above, and FIG. On the rear surface A of the dielectric substrate 1, microstrip lines 4 (transparent) for both unmodulated input lines and modulated output lines of microwave / millimeter-wave RF signals are formed. Side B is the ground conductor 5 and its ground conductor
A slot line 3 for input with a groove (slot) of constant width cut in 5 and two slot lines 3a of each length λg / 4 for modulation and synthesis that generate a phase shift amount 0-π as output. 3b and two switch devices 2a and 2b according to the present invention can be installed in series from the two branch points of the input slot line 3 in the direction of the two slot lines 3a and 3b. Further, the circuit of the balanced phase modulator is formed by the slot lines 3c and 3d of integer times n (n = 1 in the example of FIG. 1) of each length λg / 2. The output end of the input slot line 3 is branched into two slot lines 3c and 3d, and then the slot lines 3a and 3b for modulation and synthesis of the final output portions of the respective slots.
Connected to. Λg / 2 which is half the wavelength λg from the branch point
The position of the distance of an integer n times (n = 1 in FIG. 1) is also the position of the input ends of the two slot lines 3a and 3b having the respective lengths λg / 4. Since the positions can be sufficiently separated from each other, a pair of diodes 2a and 2b which are switch devices are arranged in opposite directions. The diodes 2a and 2b are mounted so as to straddle each slot at the connection part of the slot lines 3c and 3a and the connection part of the slot lines 3d and 3b, and one of them is connected to the ground conductor 5 and the other is connected to the slot line 3a. , 3b, 3c, 3d, and is connected to the conductor 6 for an electrode which is an island. At this time, the direction of the pair of diodes 2a and 2b is reverse parallel so that one of them is connected to the cathode side and the other is connected to the electrode conductor 6 on the anode side. The switching operation of the diodes 2a and 2b is performed by a low-frequency input signal (modulation signal) having a positive / negative polarity applied by an external lead 7 connected to the conductor 6. In a certain state "positive polarity" of the input signal (modulation signal) having a positive / negative polarity applied from the external lead 7, the positive polarity signal is applied to the anode of the diode 2b to cause a short circuit (ON). Make a state. At this time, the point distant from the diodes 2a and 2b by λg / 2 toward the input branch point, that is, the input end of 3c on the slot line 3a side, which is the branch point, is short-circuited (turned on) at high frequency. RF input as it is made
The signal does not pass through the branch lines 3c and 3a whose input ends are short-circuited, while passing through the branch lines 3d and 3b whose input ends are open (OFF). If a negative signal is applied to the anode of diode 2b, it will be branched
The input RF signal passes through the 3c and 3a sides. As a result, a low-frequency signal (modulation signal) with positive and negative polarities of the external input
As a result, a high frequency signal of the modulated output of the balanced modulator having a phase shift amount of 0-π with respect to the high frequency signal of the input is obtained.

FIG. 2a is a block diagram of an embodiment corresponding to claim 3 of the present invention. Similar to the embodiment of FIG. 1, a microstrip line 4 (transparent) for RF signal input / output lines is formed on the A surface of the back surface of the dielectric substrate 1, and the B surface of the front surface is the ground conductor 5. From the two branch points of the input slot line 3 so that the slot lines 3, 3a, 3b and the two switch devices 2a, 2b can be actually equipped in the ground conductor 5 of The two slot lines 3a, 3
A balanced modulation circuit is constructed by slot lines 8a and 8b for short stubs each having a length of λg / 2 newly installed in parallel with b. Also in this embodiment, the line length of each of the slot lines 3a and 3b, which are the lines for modulation and synthesis on the two slot lines into which the input slot line 3 is branched, is set to λg / 4, but generally λg It is set to an odd multiple of / 4. In this embodiment, an auxiliary line called a short stub that is an integer multiple of each length λg / 2 (in this example, an integer multiple) in parallel with each slot line 3a, 3b of each λg / 4 near the branch point of the input signal. 8
a and 8b are arranged, and the diodes 2a and 2b are mounted at positions separated from each other by an odd multiple of the length λg / 4 (one odd in this example) from the branch point in the middle. A low frequency applied voltage having a positive / negative polarity, which is a modulation signal input to the diodes 2a and 2b, is configured so that one of them is applied from the anode of 2a and the other is applied from the cathode of 2b. In a certain “positive polarity state” of the applied modulation signal input, the positive polarity voltage is applied to the diode 2a to create a short circuit (ON) state. At this time, since the auxiliary line 8a operates as a short stub with a length of λg / 4, an open (off) state is created at a high frequency at a point λg / 4 away from the branch point, that is, the input point The RF signal is disconnected or attenuated at the input end of the branch line 3a, which is the branch point, and mainly passes through the branch line 3b in which the other diode 2b is turned off. When a negative voltage is applied to the diode 2a, on the contrary, the auxiliary line
8a operates as a short stub with a length of λg / 2, because the diode 2b at the position of λg / 4 from that branch point is in an open state in which it is off. Therefore, R input from slot line 3
The F signal passes through the branch line 3a short-connected to the slot line 3, and as a result, the modulated output of the balanced phase modulator with the phase shift amount 0-π is obtained by turning on / off the diodes 2a and 2b. .

FIG. 2B shows a mounting example used for improving the switching characteristics of the diode 2 (2a, 2b).
Provide two open stubs 11a, 11b with low impedance and length λg / 4 beside the main slot line 3 (3a, 3b) for the input signal, and use one open pattern 12 at the tip in common. The electrode conductor that applies the modulation signal with positive and negative polarities.
Form 9 as an island. At this time, open stub 11a, 11
The connection point between b and the slot line 3a, 3b of the main line of the input signal is a short-circuit point, so that unnecessary reactance caused by providing the electrode 9 is reduced.

FIG. 3 shows the configuration of an embodiment corresponding to claim 4 of the present invention. The two auxiliary lines 8a and 8b of the short stub with the length λg / 2 in FIG. 2A are replaced by two open stubs with an odd multiple of the length λg / 4 (an odd number in this example). It is replaced with lines 10a and 10b. The mounting of the diodes 2a and 2b is the same as that of the embodiment shown in FIG. In a certain state "positive polarity" of a modulation signal having positive and negative polarities applied and input from the outside, a signal of positive polarity is applied to the diode 2a to turn it on to create a short circuit state. At this time, the auxiliary line 10a has a length λ
Since it operates as a g / 4 short stub, an open state (off) is created at a high frequency at a point separated by a length λg / 4 toward the branch point, that is, at the branch point. Therefore, the input RF
The signal is broken or attenuated in the branch line 3a and mainly passes through the branch line 3b. On the contrary, when a negative voltage is applied to the diode 2a, the auxiliary line 10a operates as an open stub with a length of λg / 4, so that a short circuit (on) state is created at the branch point, and the input RF signal is generated. Passes the branch line 3a,
As a result, when the diodes 2a and 2b are turned on and off, the output terminals of the two lines 3a and 3b with a length of λg / 4 are opened / shorted, and the combined output of the phase shift amount 0-π The operation will be performed.

4A and 4B show the diode 2 (2a, 2b).
5 and 6 of the present invention for improving the switch characteristics of
An example of implementation corresponding to is shown. Figure 4 (b) shows the diode 2 (2
(a, 2b) is mounted on a part of the slot line 3 (3a, 3b) that has a wide slot width to make it a high-impedance line, so that the short-circuited state of the slot line 3 is ideal. This is to improve the switching characteristics of the diode 2 by bringing them closer to each other. In FIG. 4 (a), an inductive short stub 13 shorter than λg / 4 is set up near the diode 2 to resonate in parallel with the junction capacitance of the diode 2. As a result, the open state of the slot line 3 is brought close to an ideal one, and the switching characteristics of the diode 2 are improved. In either case of (a) and (b) of FIG. 4, by using it in combination with the embodiment shown in FIGS. 1 to 3, it is possible to obtain a phase modulator with a phase shift amount of 0-π of a slot line balanced modulator. The effect of further improving the modulation characteristic can be obtained.

The technical idea of the present invention is not limited to the above-described embodiment, and the slot lines 3a and 3b each having a length λg / 4 for modulation and combination provided on the branch line have a wavelength λg / 4. The length may be an integral multiple, and need not be equal. However,
In order to maintain the balance of the branch line circuit, it is necessary to add an auxiliary line in front of each switch device so that the length from the branch point to the composite point is equal for the two branch lines. There is.

Further, the technical idea of the present invention is not limited to the balanced modulator by the slot line formed by cutting the groove on the ground conductor surface of the dielectric substrate, and the dielectric substrate is provided on the surface opposite to the ground conductor surface. It goes without saying that the present invention is also applied to a balanced modulator using strip lines of conductor pieces for high-frequency signal transmission formed separately.

[0015]

As described above, according to the present invention, each final phase-modulating composite line of two slot lines obtained by bifurcating an input high-frequency signal is a slot line having a length λg / 4. A pair of switch devices, which are originally arranged at the branch point which is the input end of the, and are turned on / off by the low frequency modulation signal input, are connected in series in the direction of the synthetic line from the branch point with each length λg / 2. The size of the switch device can be adjusted by installing the switch device at the output terminal of the slot line that is extended by λg / 4 as a stub from the branch point in parallel with each branch line. A microwave with a size that cannot be ignored compared to a line with a wavelength of λg / 4 for high-frequency signals.
Even when the millimeter-wave ultra-high-frequency signal becomes an input signal, it is possible to perform the same high-frequency operation as that for a high-frequency signal with a negligible low frequency, so it is particularly effective in the millimeter-wave band where the wavelength is short. Even if the effective wavelength λg is reduced using a substrate with a dielectric constant, the amount of phase shift due to the slot line is 0-π
The effect of easily realizing the balanced modulator of is obtained.

[Brief description of drawings]

1 is a principle configuration diagram of a slot line balanced modulator according to claim 1 of the present invention, and a circuit configuration diagram of an embodiment corresponding to claim 2;

FIG. 2 is a circuit configuration diagram of a slot line balanced modulator of an embodiment corresponding to claim 3 of the present invention.

FIG. 3 is a circuit configuration diagram of a slot line balanced modulator of an embodiment corresponding to claim 4 of the present invention.

FIG. 4 is a configuration diagram for improving a switching effect of a diode in an embodiment corresponding to claims 5 and 6 of the present invention.

FIG. 5 is a circuit configuration diagram of a conventional slot line balanced modulator.

[Explanation of symbols]

Reference numeral 1 is a dielectric substrate, 2, 2a and 2b are switch devices, a pair of diodes, 3, 3a and 3b are slot lines, 3c and 3d are auxiliary lines that are integral multiples of λg / 2 newly established by the present invention, and 4 is an input line. Output microstrip line, 5 is ground conductor, 6 is diode
The conductor for the electrode of 2, the lead for applying the low frequency modulation signal of the external input, 8a and 8b are the slot lines newly established in the present invention as auxiliary lines, the short stub with the length λg / 2,
9 is an electrode conductor for diode 2, 10a and 10b are also slot lines as auxiliary lines, open stubs with length λg / 4, 11a and 11b are slot lines with low impedance and length λg / 4. A stub, 12 is an open pattern for an open stub, 13 is a slot line for parallel resonance with the junction capacitance of the diode 2, and is an inductive short stub with a length of λg / 4 or less.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masafumi Shigaki 4-1-1 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (6)

[Claims] 1. A synthetic output length λg / 4 of each final part of two slot lines for bifurcating two high frequency signals having a wavelength λg input by a slot line formed on one side of a ground conductor surface of a dielectric substrate. Each of the pair of switch devices at each input end of the slot line is turned on / off by a low frequency modulation signal having a positive / negative polarity of the external input, and the output end of the slot line of λg / 4 is synthesized as an open / short state and transferred. In a slot-line balanced modulator that obtains a modulated output with a phase amount of 0-π, the mounting position on the line of the pair of switch devices is from a branch point different from the branch point of the slot line that splits the input high-frequency signal into two. Circuit means for arranging them at positions separated from each other by a certain specific length, and by turning them on / off, a state in which the output end of the slot line of each length λg / 4 is opened / shorted at high frequency That Characteristic slot line balanced modulator. 2. A certain position in the circuit means of claim 1 where each of the pair of switch devices is arranged on a line is a length λg / 4 of the input signal divided into two.
Wavelength series λg from the branch point in series in the direction of the slot line of
A slot line balanced modulator, characterized in that the position of the output end of the line having a length that is an integral multiple of half is set. 3. A particular position in the circuit means of claim 1 in which each of the pair of switch devices is disposed,
A short stub having a length of an integral multiple of half the wavelength from the branch point is provided in parallel with each slot line having a length of λg / 4 obtained by branching the input signal from the branch point to the wavelength of the stub. A slot line balanced modulator characterized in that the position is an odd multiple of 1/4. 4. A particular position in the circuit means of claim 1 in which each of the pair of switch devices is disposed,
An open stub having a length that is an odd multiple of 1/4 of the wavelength from the branch point is provided in parallel with each slot line having a length of λg / 4, which is obtained by branching the input signal. A slot line balanced modulator characterized in that it is located at a distance that is an odd multiple of 1/4 of the wavelength. 5. When the pair of switch devices in the circuit means according to claim 1 is mounted at a predetermined position on a slot line, a high impedance line having a slot width wider than the main slot line is provided. A slot line balanced modulator characterized by mounting the pair of switch devices. 6. When using a diode as the pair of switch devices in the circuit means of claim 1, an inductive short stub having a length shorter than 1/4 wavelength is provided beside the main slot line. A slot line balanced modulator characterized in that it is provided and resonates in parallel with the junction capacitance of each diode.