JP2005333375A - Microwave phase shifter and wireless machine using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave phase shifter stabilizing frequency-change characteristics of a phase-shift quantity to voltage characteristics to a wider frequency. <P>SOLUTION: Capacitive stubs 10 are connected in series with two variable capacity elements 6 constituting the microwave phase shifter, respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microwave phase shifter used for a microwave band radar device or a communication device. The present invention also relates to a radio using this microwave phase shifter.

  A transmission module or a reception module for amplifying or controlling a microwave signal is used for a communication device or the like in the microwave band. In these modules, those whose amplitude and phase do not change with respect to the ambient temperature are desirable, and therefore an attenuator and a phase shifter for compensating the temperature characteristics are used. The present invention relates to a phase shifter for performing such phase compensation.

  For example, FIG. 13 of Patent Document 1 discloses a configuration of a conventional microwave phase shifter. The figure shows a 90 ° hybrid 1, an input terminal 2, an isolation terminal 3, a coupling terminal 4, a passing terminal 5, a variable capacitance element (a varactor diode element or FET described later) 6, a choke circuit 7, and a DC power supply 8. ing.

  This phase shifter is provided with a variable capacitance element 6 between the coupling terminal 4 of the 90 ° hybrid 1 having four terminals and the ground, and between the passage terminal 5 and the ground, and each variable capacitance element 6 has a desired DC bias voltage. Is applied to each variable capacitance element 6 through a choke circuit 7 that cuts the microwave frequency.

  The 90 ° hybrid 1 is of a type such as a so-called branch line coupler, an interdigital coupler, or the like, that is, a type in which the coupling terminal 4 and the passing terminal 5 have the same amplitude and a phase difference of 90 ° is output. Things are used.

  As the variable capacitance element 6, a varactor diode element, an FET, or the like is used. In general, a varactor diode is represented by a series circuit of an inductor Ld, a series resistance Ri, and a junction capacitor Cj caused by bonding wires inside / outside the element, as shown in an equivalent circuit in the above-described figure. This junction capacitor Cj is controlled by the applied voltage VR of the DC power supply 8, and Cj decreases as VR increases.

  The choke circuit 7 is designed to have a high impedance in a desired frequency band so as not to affect the microwave characteristics, and a desired voltage VR is supplied from the DC power supply 8 via the choke circuit 7 to the variable capacitance element. 6 to change its capacity.

  Before explaining the problems of the conventional microwave phase shifter, the operation of what has been disclosed in the above-mentioned drawings will be described for the sake of understanding. The microwave signal input from the input terminal 2 is distributed by the 90 ° hybrid 1 to the coupling terminal 4 and the passing terminal 5 with the same amplitude and 90 ° phase difference, respectively. The distributed microwave signals are respectively supplied to the variable capacitance elements 6. The supplied microwave signals are reflected to the 90 ° hybrid 1 side with a reflection phase corresponding to the capacitance of the variable capacitance element 6. Further, each reflected microwave signal is output to the isolation terminal 3 because the input terminal 2 performs reverse-phase synthesis and the isolation terminal 3 performs in-phase synthesis.

  In order to explain the problem of the conventional microwave phase shifter, FIGS. 14 and 16 show the impedance Za locus of the variable capacitance element 6 on the Smith chart. FIG. 14 shows a case where the frequency used is relatively low, and FIG. 16 shows a case where the frequency used is relatively high. In FIG. 14, the angular frequency ω = ω0 is constant (the case of ω1 and ω2 in the figure will be described later), and the voltage VR applied to the variable capacitor 6 is VR1, VR0, VR2 (the magnitude relationship of the voltages). (VR1 <VR0 <VR2), and is normalized with a normalized impedance Z0 (usually 50Ω). When the frequency is low, since the impedance of the inductor Ld caused by the bonding wire is low and the influence is small, the impedance of the variable capacitance element 6 in FIG. 14 is capacitive (−j side).

Further, as shown in FIG. 14, by increasing the voltage VR of the DC power supply 8 from VR1 to VR2, the junction capacitor Cj of the variable capacitance element 6 is gradually decreased, and Za is counterclockwise on a line having a constant resistance component. Change.
Furthermore, the absolute value of the reflection coefficient in the variable capacitance element 6 is determined by the distance from the center of the Smith chart, and the internal resistance value Ri of the varactor diode is very small (≈0 ohms). As VR increases, the phase advances. The loss of this type of microwave phase shifter is inversely proportional to the absolute value of the reflection coefficient, and the loss decreases as the absolute value increases.
Also, as shown in FIG. 14, when the angular frequency ω is lowered to ω1 (the magnitude relationship of ω is ω1 <ω0 <ω2), the influence of the capacitance is reduced, so that the amount of phase change with respect to a constant voltage change is reduced. (The interval between VR1 and VR2 becomes narrow on the Smith chart).
This relationship is shown in FIG.

FIG. 16 shows a case where the microwave frequency is high. In FIG. 16, the voltage VR applied to the variable capacitance element 6 is changed to VR1, VR0, VR2, the angular frequency ω is changed to ω1, ω0, ω2, and the normalized impedance Z0 ( It is a figure normalized by (normally 50Ω). By increasing the frequency, the impedance of the inductor Ld of the bonding wire used inside / outside the variable capacitance element 6 becomes large, and the influence appears, and the characteristic shows inductivity (+ j side) as a whole. Then, as shown in FIG. 16, when the angular frequency ω is increased to ω2, the amount of phase change with respect to a constant voltage change becomes small (the interval between VR1 and VR2 becomes narrow on the Smith chart).
This relationship is shown in FIG.

From FIG. 15 and FIG. 17, the frequency characteristic of the amount of phase shift with respect to a constant voltage change width becomes smaller than that at the middle frequency when the frequency ω is used in a very high or very low region.
Conventionally, a microwave phase shifter having such characteristics that can control the phase according to the temperature by controlling the DC power supply voltage VR according to the temperature change of the module has been used. In general, the phase of amplifiers, attenuators, and the like that constitute a microwave transmission / reception module changes with temperature. Therefore, by mounting this microwave phase shifter on the module and changing the DC voltage VR according to the temperature fluctuation of the phase of the module, the phase fluctuation of the module can be offset, so the phase fluctuation with respect to the temperature It is used as a method for obtaining a small microwave module.
However, as shown in the characteristic diagrams of FIGS. 15 and 17, the phase shift amount vs. voltage VR characteristics at a high or low frequency far from the center frequency are the phase shift amount vs. voltage VR characteristics at the center frequency. Therefore, the voltage control amount for a constant temperature change must be changed according to the level of the frequency, and if it is controlled at the same level, there is a problem that the temperature fluctuation characteristic cannot be suppressed accurately. .
As a countermeasure for such a problem, there is a method of having a table for each appropriate frequency interval for the phase shift amount, the voltage characteristic, and the voltage characteristic of the microwave phase shifter, and selectively using the table according to the change of the operating frequency. However, the control is complicated, and it can be applied only to transmission / reception of one frequency, and cannot be applied because it is not possible to select one table for simultaneous transmission / reception of a plurality of signals with a large frequency difference. Met.

JP 2003-264403 A

  As described above, in the conventional microwave phase shifter, the phase shift amount vs. voltage characteristics at a high or low frequency far from the center frequency and the phase shift amount vs. voltage characteristics at the center frequency Therefore, there is a problem that when the frequency is controlled to be high / low, a predetermined phase shift amount cannot be obtained when the control is performed with a constant phase shift amount / vs. Voltage characteristic.

  The present invention has been made to solve the above-described problems, and the microwave phase shift in which the frequency change characteristic of the phase shift amount versus the voltage characteristic is stabilized with respect to a wider frequency (hereinafter referred to as a broad band). The purpose is to provide a vessel.

The microwave phase shifter of the present invention includes a 90 ° hybrid having an input terminal, a coupling terminal, a passing terminal, and an isolation terminal, a variable capacitance element having one end connected to the coupling terminal and the passing terminal,
A capacitive stub is connected to each other end of the variable capacitance element and adjusted so that the impedance viewed from the other end is capacitive.

  The wireless communication device of the present invention includes the microwave phase shifter.

Also, a communication module that transmits and receives microwaves,
The microwave phase shifter according to any one of claims 1 to 7,
A power supply circuit for supplying a DC bias voltage to the capacitive element;
A control circuit that detects the temperature of the communication module and controls the output voltage of the power supply circuit based on the temperature is provided.

  According to the present invention, the frequency characteristic of the voltage versus phase shift amount can be widened. By applying this to the temperature compensation of the phase of the transmission / reception module, it is possible to obtain a module having a small phase variation with respect to temperature at a wide frequency range.

Embodiment 1 FIG.
In the following description of the drawings, the same reference numerals indicate the same or corresponding parts. FIG. 1 shows the configuration of the microwave phase shifter according to the first embodiment, which is effective in improving the characteristics at a relatively high frequency. In the figure, a 90 ° hybrid 1, an input terminal 2, an isolation terminal 3, a coupling terminal 4, a passing terminal 5, a variable capacitance element 6, a choke circuit 7, a DC power supply 8, a capacitive stub 10, and a grounding choke 11 are shown. Yes.

  A grounding choke 11 is connected between the coupling terminal 4 and the variable capacitance element 6 of the 90 ° hybrid 1 and between each of the passage terminal 5 and the variable capacitance element 6 and the ground, and these points are connected in a direct current manner. To earth. In addition, a capacitive stub 10 (a feeder line whose length is adjusted so that the apparent impedance becomes capacitive at the operating frequency by short-circuiting or opening the tip) is connected to the terminal of the variable capacitive element 6. As shown in the figure, the capacitive stub 10 can be equivalently represented by a capacitor 10a and an alternating earth 10b.

  The impedance Za locus of the variable capacitor 6 alone in FIG. 1 is FIG. 16 shown in the conventional explanation at a high frequency. As shown in FIG. 16, when the angular frequency ω is increased to ω2, the influence of the inductor Ld caused by the bonding wire is increased, so that the amount of change in phase when VR is constantly changed is decreased. Therefore, when used in a region where the angular frequency ω is high, the frequency characteristic of the phase shift amount becomes large.

  Therefore, by connecting the capacitive stubs 10 of appropriate values in series as shown in FIG. 1, the Za locus becomes the impedance Zb locus of the variable capacitance element 6 viewed through the capacitive stub 10 as shown in FIG. 2. Move to. At this time, even when the frequency ω2 is high, the phase change when the voltage VR is changed from VR1 to VR2 becomes large. Conversely, at ω1 where the angular frequency is low, the phase change when the voltage VR is changed is shown in FIG. Smaller than shown. FIG. 3 is a graph showing the frequency characteristic of the voltage versus phase shift amount characteristic when the voltage VR is changed, normalized by the phase at the center voltage VR0. By appropriately adjusting the value of the capacitive stub 10, the phase shift amount frequency characteristic flattened at the central angular frequency ω0 can be obtained.

  When a varactor diode is used as the variable capacitance element 6, the internal resistance value Ri is very small. Therefore, when Ri = 0 ohms, the change in the phase shift amount when the voltage is changed is maximized. The angular frequency ω0 is obtained by the following equation.

FIG. 4 shows an example of the structure of the microwave phase shifter shown in FIG. The circuit is developed on a substrate 100 having a side of several tens of millimeters. The ground line is not shown. The power supply circuit 8 is externally attached. The dimensions of each part are appropriately designed in consideration of the wavelength of the microwave, and the whole is housed in a shield case (not shown).
As described above, the microwave phase shifter according to the present invention can broaden the frequency characteristic of the voltage versus phase shift amount characteristic in a desired frequency band.

Embodiment 2. FIG.
FIG. 5 shows the configuration of the microwave phase shifter according to the second embodiment, and there is an improvement effect at a relatively low frequency. Inductive elements 12 are provided between the two variable capacitance elements 6 and the ground (on the side not connected to the hybrid 1) so as to be connected in series to the variable capacitance elements 6, respectively.
This series connection may be on either side of the variable capacitance element 6.

  The impedance locus of the variable capacitor 6 alone is shown in FIG. 10 of the conventional example at a low frequency. As shown in the figure, as described above, when the angular frequency ω is lowered to ω1, the influence of the capacitance is reduced, so that the amount of change in phase due to the change in VR is reduced. Therefore, when used in a region where the angular frequency ω is low, there is a problem that the frequency characteristic of the phase shift amount becomes large.

  Therefore, by connecting inductive elements 12 having appropriate values in series as shown in FIG. 5, the impedance locus of FIG. 10 can be obtained from the variable capacitance element 6 viewed through the inductive elements 12 as shown in FIG. 6. Move to the impedance Zb locus. At this time, even when ω1 has a low angular frequency, the phase change when the voltage VR is changed from VR1 to VR2 becomes large. Conversely, with ω2 having a high angular frequency, the phase change when the voltage VR is changed is much greater. Becomes smaller. FIG. 7 is a graph showing the frequency characteristic of the voltage versus phase shift amount characteristic when the voltage VR is changed, normalized by the phase at the center voltage VR0. By appropriately adjusting the value of the inductive element 12, it is possible to obtain a frequency characteristic flattened at the center frequency ω0.

  Similarly to the first embodiment, since the internal resistance value Ri of the varactor diode is very small, when Ri = 0 ohms, the angular frequency at which the change in the phase shift amount when the voltage is changed is maximized. ω is obtained by the equations (1) and (2) of the first embodiment.

FIG. 8 shows an embodiment of the structure of the microwave phase shifter shown in FIG. The circuit is developed on a substrate 100 having a side of several tens of millimeters. The ground line is not shown. The power supply circuit 8 is externally attached. The dimensions of each part are appropriately designed in consideration of the wavelength of the microwave, and the whole is housed in a shield case (not shown). The difference from FIG. 4 of the first embodiment is that the size of the hybrid 1 is increased because the target frequency is lowered.
As described above, the microwave phase shifter according to this embodiment can broaden the frequency characteristic of the voltage versus phase shift amount characteristic in a desired angular frequency band.

Embodiment 3 FIG.
FIG. 9 shows the configuration of the microwave phase shifter of the third embodiment. Inductive stubs 13 are provided between the two variable capacitance elements 6 and the ground (the side not connected to the hybrid 1 of the variable capacitance elements 6) so as to be connected in series to the variable capacitance elements 6, respectively. .

This microwave phase shifter has the same basic configuration as that of FIG. 5 except that an inductive stub 13 is used instead of the inductive element 12 shown in FIG. 5 of the second embodiment. An inductive stub 13 having the same inductance value as that of the inductive element 12 in FIG. 5 is used. Since the operation principle is exactly the same as in the second embodiment, description thereof is omitted.
FIG. 10 shows a structural example of the microwave phase shifter of FIG. The circuit is developed on a substrate 100 having a side of several tens of millimeters. The ground line is not shown. The power supply circuit 8 is externally attached. The dimensions of each part are appropriately designed in consideration of the wavelength of the microwave, and the whole is housed in a shield case (not shown).

Embodiment 4 FIG.
Similar to the first embodiment, the microwave phase shifter according to this embodiment is highly effective for high frequencies. FIGS. 11 and 12 show the configuration of the microwave phase shifter according to the fourth embodiment, in which a capacitive element 9 is connected in series with a variable capacitive element 6. The method of serial connection may be as shown in FIG. 11 or as shown in FIG.

  By connecting the capacitive elements 9 having appropriate values in series as shown in FIGS. 11 and 12, the Za locus can be changed through the capacitive element 9 as shown in FIG. 2 of the first embodiment. It moves to the impedance Zb locus of the capacitive element 6. At this time, even when ω2 has a high angular frequency, the phase change when the voltage VR is changed from VR1 to VR2 becomes large. Conversely, with ω1 having a low angular frequency, the phase change when the voltage VR is changed is much greater. Becomes smaller. Then, a graph of frequency characteristics of voltage versus phase shift amount characteristics as shown in FIG. 3 of the first embodiment is obtained. By appropriately adjusting the value of the capacitive element 9, the phase shift amount frequency characteristic flattened at the center angular frequency ω 0 can be obtained.

Also, since the internal resistance value Ri of the varactor diode is very small, when Ri = 0 ohms, the angular frequency ω0 at which the change in the amount of phase shift when the voltage is changed is the maximum in the first embodiment. It is obtained by equations (1) and (2).
FIG. 13 shows a structural example of the microwave phase shifter of FIG. The circuit is developed on a substrate 100 having a side of several tens of millimeters. The ground line is not shown. The power supply circuit 8 is externally attached. The dimensions of each part are appropriately designed in consideration of the wavelength of the microwave, and the whole is housed in a shield case (not shown).

  The microwave phase shifter of the present invention can be used for a transceiver, a communication device, and a radar that use microwaves.

It is a figure which shows the structure of the microwave phase shifter of Embodiment 1 by this invention. It is a characteristic view for demonstrating operation | movement of the thing of FIG. It is a characteristic view of the microwave phase shifter of FIG. It is a figure which shows the structural example of the microwave phase shifter of FIG. It is a block diagram of the microwave phase shifter of Embodiment 2 by this invention. It is a characteristic view for demonstrating the operation | movement of FIG. It is a characteristic view of the microwave phase shifter of FIG. It is a figure which shows the structural example of the microwave phase shifter of FIG. It is a block diagram of the microwave phase shifter of Embodiment 3 by this invention. It is a figure which shows the structural example of the microwave phase shifter of FIG. It is a block diagram of the microwave phase shifter of Embodiment 4 by this invention. It is a figure which shows the other structure of the microwave phase shifter of Embodiment 4 by this invention. It is a figure which shows the structural example of the microwave phase shifter of FIG. It is characteristic explanatory drawing for demonstrating the subject of the conventional microwave phase shifter. It is a characteristic view explaining the problem of the characteristic of FIG. It is characteristic explanatory drawing for demonstrating the subject of the conventional microwave phase shifter. It is a characteristic view explaining the problem of the characteristic of FIG.

Explanation of symbols

1 90 ° hybrid, 2 input terminals, 3 isolation terminals,
4 coupling terminal, 5 passing terminal, 6 variable capacitance element, 7 choke circuit,
8 DC power supply, 9 capacitive element, 10 capacitive stub, 11 choke circuit,
12 inductive elements, 13 inductive stubs, 100 printed circuit boards.

Claims (9)

A 90 ° hybrid having an input terminal, a coupling terminal, a passing terminal and an isolation terminal, a variable capacitance element having one end connected to the coupling terminal and the passing terminal,
A microwave phase shifter comprising a capacitive stub connected to each other end of the variable capacitance element and adjusted so that impedance seen from the other end is capacitive. A 90 ° hybrid having an input terminal, a coupling terminal, a passing terminal and an isolation terminal, a variable capacitance element having one end connected to the coupling terminal and the passing terminal,
A microwave phase shifter comprising an inductive element connected between the other end of each of the variable capacitance elements and a ground terminal. A 90 ° hybrid having an input terminal, a coupling terminal, a passing terminal and an isolation terminal, a variable capacitance element having one end connected to the coupling terminal and the passing terminal,
A microwave phase shifter comprising an inductive stub connected to each other end of the variable capacitance element and adjusted so that an impedance viewed from the other end is inductive. A 90 ° hybrid having an input terminal, a coupling terminal, a passing terminal and an isolation terminal, a variable capacitance element having one end connected to the coupling terminal and the passing terminal,
A microwave phase shifter comprising: a capacitive element connected between the other end of each of the variable capacitive elements and a ground terminal. A 90 ° hybrid having an input terminal, a coupling terminal, a passing terminal and an isolation terminal, a capacitive element having one end connected to the coupling terminal and the passing terminal,
A microwave phase shifter comprising: a variable capacitance element connected to the other end of the capacitive element and having the other end grounded.   The microwave phase shifter according to claim 1, wherein the capacitive stub is an open-ended stub.   The microwave phase shifter according to claim 3, wherein the inductive stub is a tip short-circuited stub.   A wireless device comprising the microwave phase shifter according to claim 1. A communication module that transmits and receives microwaves,
The microwave phase shifter according to any one of claims 1 to 7,
A power supply circuit for supplying a DC bias voltage to the capacitive element;
A wireless device comprising a control circuit that detects a temperature of the communication module and controls an output voltage of the power supply circuit based on the temperature.

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