JP2008271408A - Phase shift circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase shifter that sufficiently suppresses variations in passing loss associated with impedance mismatching between phase shifters during the phase shift. <P>SOLUTION: A PIN diode can be equivalently considered as a pure resistor when applied with a forward bias voltage. A forward bias current of the PIN diode is changed so as to change a resistance value. Thus, it is possible to attenuate signals inputted to phase shifters. Consequently, it is possible to sufficiently suppress variations in passing loss associated with impedance mismatching between phase shifters during the phase shift. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a phase shift circuit in which phase shifters are connected in multiple stages.

  A phase shifter is a device that can arbitrarily control the phase of various signals according to a change in applied DC voltage. Phase shifters are very useful in wireless communication equipment and other electronic equipment fields, and are used in various applications such as linearizers and power combiners.

  The performance required for the phase shifter is first that the phase variable range is large, but it can be mentioned that the passage shift fluctuation of the phase shifter is small when the phase changes. In order to increase the phase variable range within the limited DC voltage range, the phase shifters may be connected in multiple stages.

However, when changing the phase by changing the DC voltage to be applied, the input / output impedance of the phase shifter changes not a little, so if the phase shifter is connected directly in multiple stages, there will be impedance mismatch between the stages when the phase changes And pass loss increases. As means for solving this, it is possible to insert an isolator between the phase shifters and isolate the phase shifters. However, the isolator is expensive and has a drawback that the mounting area is increased.
Therefore, there is a need for a technique for suppressing an increase in passage loss when the phase changes in a multistage phase shifter.

First, FIG. 8 shows a conventional example of a one-stage reflection type phase shifter.
A high-frequency signal input terminal 1-3, a high-frequency signal output terminal 2-3, a direct-current voltage application terminal 3-3 for applying a direct-current voltage for changing the inter-terminal capacitance of the variable capacitance element, direct-current voltage blocking capacitors 4a and 4b, The RF choke coils 5a and 5b, 90 for synthesizing the high-frequency signals phase-shifted due to the capacitance change between the terminals of the variable capacitance element and isolating the high-frequency signal input terminal 1-3 and the high-frequency signal output terminal 2-3. A 3 dB hybrid 6, a varactor diode 7a and a varactor diode 7b as variable capacitance elements, a DC voltage blocking capacitor 8a and a DC voltage blocking capacitor 8b, a resistor 9a and a resistor 9b.

  In the varactor diode 7a and the varactor diode 7b, either the anode electrode or the cathode electrode is grounded (in the example of FIG. 8, the cathode electrode is grounded), and the other electrode is connected to the RF voltage application terminal 3-3 through RF. A reverse bias voltage is applied through the choke coil 5a and the RF choke coil 5b. By changing the value of the reverse bias voltage, the capacitance between the terminals of the varactor diode 7a and the varactor diode 7b is changed. By changing the inter-terminal capacitance and changing the reflection impedance of the varactor diode 7a and the varactor diode 7b, the phase change of the signal is realized. The resistor 9a and the resistor 9b are for suppressing a passage loss change at the time of phase shift per one stage phase shifter, but since the operation principle is described in detail in Japanese Patent Laid-Open No. 4-47801, The description is omitted here.

  In order to realize a large amount of phase shift, as shown in FIG. 9, phase shifters may be connected in multiple stages, and a common variable DC voltage may be applied to each phase shifter from the DC voltage application terminal 3-4. However, in this case, the input / output impedance of the phase shifter changes at the time of phase shift, impedance mismatch between stages occurs, and fluctuation occurs in the passage loss between the terminals 1-4 and 2-4. Although the isolator 10 is inserted between the stages of the phase shifter in FIG. 9 in order to suppress it, the isolator is generally expensive and the mounting area increases, so avoid using it as much as possible. I want.

  Therefore, when configuring a multistage phase shifter, a technique is required that realizes the suppression of the passage loss fluctuation associated with the interstage impedance mismatch at the time of phase shifting with a low cost and a small mounting area.

  In response, various phase shifters have been proposed. That is, there is a multi-stage phase shifter (for example, refer to Patent Document 1) including a broadband edge guide mode circulator and a semiconductor element that is connected to a connection terminal of the broadband edge guide mode circulator and changes a reflection phase according to a bias state. .

  The input high-frequency signal is branched from the input terminal to the passing terminal and the coupling terminal by the 90-degree hybrid, and n diodes that are short-circuited or opened at the input terminal respectively connected to the passing terminal and the coupling terminal; Two series of reflected signals reflected by the ground terminal in series connection with the transmission line of n types of electrical length are combined and output at the output terminal through the hybrid pass-through terminal and coupling terminal, and input at the output terminal. A reflection type phase shifter that obtains an output signal obtained by adding a predetermined phase shift amount to the input signal of the diode, and is short-circuited or opened at each input end so as to obtain a desired plurality of phase shift amounts And a phase shifter (see, for example, Patent Document 2) provided in multiple stages with transmission lines having different electrical lengths.

Furthermore, a variable phase shifter capable of adjusting the amount of phase shift, a variable attenuator capable of adjusting the amount of attenuation, a band-pass filter, and a connection circuit of two, which are subordinately connected variable shifts constituting an auxiliary circuit. An electronic device in which a phase shifter and a variable attenuator are connected between an input unit and an output unit of a band pass filter via a connection circuit, respectively, and a variable phase shifter and a variable attenuator are configured using active elements. A tunable polarized filter (see, for example, Patent Document 3) is also included.
Japanese Utility Model Publication 2-75801 JP-A-8-97602 JP-A-10-256809

However, in the above-described conventional technology, the suppression of the passage loss variation due to the impedance mismatch between the phase shifters at the time of phase shift is insufficient.
SUMMARY OF THE INVENTION An object of the present invention is to provide a phase shifter that can sufficiently suppress fluctuations in passage loss due to impedance mismatch between phase shifters during phase shift.

  In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is that a phase shifter connected in multiple stages, a voltage dividing circuit for dividing a DC variable voltage, and a voltage divided by the voltage dividing circuit are applied. And a PIN diode for attenuating the signal passing through the phase shifter.

  According to the first aspect of the present invention, when the forward bias voltage is applied, the resistance value is changed by changing the forward bias current of the PIN diode that can be regarded as a pure resistance equivalently. Therefore, the fluctuation of the passage loss due to the impedance mismatch between the phase shifters during the movement can be sufficiently suppressed.

  According to a second aspect of the present invention, there are provided a phase shifter connected in multiple stages, a voltage dividing circuit that divides a DC variable voltage, and a voltage that is connected to any of the phase shifters and divided by the voltage dividing circuit is a cathode. And a PIN diode for attenuating a signal passing through the phase shifter when applied to the electrode.

  According to the second aspect of the present invention, the resistance value between the input terminal and the signal input terminal is changed by changing the forward bias current of the PIN diode that can be regarded as a pure resistance equivalently when a forward bias voltage is applied. By changing it, the signal input to the phase shifter can be attenuated, and the fluctuation of the passage loss due to the impedance mismatch between the phase shifters during the phase shift can be sufficiently suppressed.

  According to a third aspect of the present invention, there are provided a phase shifter connected in multiple stages, a voltage dividing circuit that divides a DC variable voltage, a resistor that allows a signal to pass through the phase shifter, and a cathode connected to both ends of the resistor via a capacitor. An electrode and an anode electrode are connected to each other, and a PIN diode that attenuates an input signal when a voltage divided by the voltage dividing circuit is applied to the cathode electrode is provided.

  According to the third aspect of the present invention, the combined resistance value between the input terminal and the signal input terminal is changed by changing the forward bias current of the PIN diode that can be regarded as a pure resistance equivalently when a forward bias voltage is applied. By changing the signal, the signal input to the phase shifter can be attenuated, and the fluctuation of the passage loss due to the impedance mismatch between the phase shifters during the phase shift can be sufficiently suppressed.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the DC variable voltage of the voltage dividing circuit is common to a power supply voltage of the phase shifter.

  According to the fourth aspect of the present invention, since the input voltage of the voltage dividing circuit is common with the power supply voltage of the phase shifter, it is not necessary to provide a new power supply, and the size can be reduced.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, between the anode electrode of the PIN diode and the input terminal, and between the cathode electrode of the PIN diode and the input terminal of the first-stage phase shifter. It is characterized in that a capacitor is inserted in each.

  According to the fifth aspect of the present invention, since excess DC component to the PIN diode is cut off, fluctuation of the passage loss can be more sufficiently suppressed.

  According to a fifth aspect of the present invention, in the invention of the third or fourth aspect, the high frequency choke coil is provided between the anode electrode of the PIN diode and the ground, and between the cathode electrode of the PIN diode and the voltage dividing circuit, respectively. It is characterized by having inserted.

  According to the fifth aspect of the present invention, the high frequency choke coil is inserted between the anode electrode of the PIN diode and the ground, and between the cathode electrode of the PIN diode and the voltage dividing circuit, so that the high frequency from the input terminal is obtained. The signal is prevented from flowing to the PIN diode, and the fluctuation of the passage loss can be more sufficiently suppressed.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the phase shifter performs in-phase synthesis of the signal phase-shifted by the variable capacitance element using a 90-degree 3 dB hybrid, and the input terminal. And a reflection type phase shifter for isolating the output end.
It is characterized by that.

  The invention according to claim 7 is the invention according to any one of claims 1 to 5, wherein the phase shifter performs in-phase synthesis of the signal phase-shifted by the variable capacitance element by a circulator, and the input end and the output end It is a reflection type phase shifter that isolates the above.

  According to the present invention, the signal input to the phase shifter is attenuated by changing the resistance value by changing the forward bias current of the PIN diode, which can be regarded as a pure resistance equivalently when a forward bias voltage is applied. Therefore, it is possible to sufficiently suppress the fluctuation of the passage loss due to the impedance mismatch between the phase shifters during the phase shift.

〔Characteristic〕
The phase shift circuit according to the present invention suppresses fluctuations in the passage loss due to impedance mismatch between the phase shifter stages during the phase shift in the phase shifter circuit connected in multiple stages to ensure a large amount of phase shift. Based on the DC variable voltage supplied to the phase shifter, the DC variable voltage optimally stepped down by the resistance voltage dividing circuit is applied to the PIN diode, and the resistance value is changed by changing the forward bias current. In this circuit, the amount of attenuation of a variable resistance attenuation circuit including a diode is changed. It can be configured with only inexpensive and small components such as a resistor, a capacitor, a coil, and a PIN diode. In addition, since the DC variable voltage supplied to the PIN diode uses the DC variable voltage supplied to the phase shifter, no new DC power supply is required. Moreover, only one circuit block needs to be added regardless of the number of stages of the phase shifter.

Next, an embodiment of the phase shift circuit according to the present invention will be described.
FIG. 1 shows an embodiment of a circuit of a phase shift circuit according to the present invention.
In order to absorb the passage loss fluctuation accompanying the impedance mismatch between the phase shifter stages at the time of phase shift, a variable resistance attenuation circuit 20 composed of a PIN diode 19 is mounted (in the figure, the variable resistance attenuation circuit 20 is in the first stage. Although implemented, the present invention is not limited to this, and may be implemented between stages of the phase shifter or at the final stage. The reflection type phase shifter shown in FIG. 1 is simply described as 11a and 11b.
Between the stages of the multistage (two stages in the example of FIG. 1) phase shifter 11a and phase shifter 11b, an impedance matching circuit 12 including a capacitor, a coil, and a distributed constant circuit is mounted.

An example of the impedance matching circuit 12 used in the phase shift circuit shown in FIG. 1 is shown in FIGS.
When the impedance matching circuit 12 is configured by a lumped constant circuit using a capacitor and a coil, the coil is connected in series and the capacitor is connected in parallel to the pair GND (FIG. 2A), the capacitor is connected in series, and the coil is connected to GND. There are various combinations such as those connected in parallel (FIG. 2B), and a plurality of these can be connected in a dependent manner. Further, when the impedance matching circuit 12 is constituted by a distributed constant circuit, the constituent elements are an open stub (FIG. 2C), a short stub (FIG. 2D), and the like. Open stubs and short stubs are not electronic components but are configured by patterns on a printed wiring board, and their characteristics differ depending on their vertical and horizontal dimensions. A plurality of these can be connected dependently.

  A variable DC voltage is supplied from the DC voltage application terminal 3-1 to each of the phase shifters 11a and 11b, and the phase is shifted by the phase shifter 11a and the phase shifter 11b due to the voltage change. At the same time, the variable DC voltage from the DC voltage application terminal 3-1 is stepped down to an appropriate voltage by the voltage dividing resistors 13 and 14, and is supplied to the cathode electrode of the PIN diode 19 through the RF choke coil 17b. The anode electrode of the PIN diode 19 is grounded via the RF choke coil 17a.

Reference numerals 18a and 18b denote DC voltage blocking capacitors, which select capacitance values having sufficiently low impedance at the frequency of the high-frequency signal to be used.
The PIN diode 19 is a variable resistance element that can be equivalently regarded as a pure resistance when a forward bias voltage is applied, and whose resistance value can be changed by changing a forward bias current. The resistance value decreases as the forward bias current increases. In the present embodiment, the DC variable voltage applied to the DC voltage application terminal 3-1 is a negative voltage.
Therefore, the anode electrode of the PIN diode 19 is grounded, and a negative voltage is applied to the cathode electrode, that is, a forward bias voltage is applied. By changing this negative voltage, it can be regarded as a variable resistor.

  Here, a circuit (variable resistance attenuating circuit: a circuit between the terminals 1-1 and 100) 20 surrounded by a dotted line in FIG. 1 is an equivalent circuit composed of resistors 15 and 16 and a variable resistor 21 as shown in FIG. FIG. 4 shows a simulation result of how the passage loss characteristics change when the resistance value of the variable resistor 21 is changed. In FIG. 4, the horizontal axis represents the resistance value of the variable resistor 21, and the vertical axis represents the pass characteristic.

  The constants of the resistors 15 and 16 can be arbitrarily selected according to desired characteristics, but the simulation results are obtained when the resistance value of the resistor 15 is 270Ω and the resistance value of the resistor 16 is 150Ω. From this result, it can be seen that when the resistance value of the variable resistor 21 is increased from 10Ω to 100Ω, the attenuation of the variable resistor attenuation circuit 20 changes from about 2.5 dB to about 6.5 dB.

  When the resistance value → higher characteristic is replaced with the phase shift circuit of FIG. 1, the forward bias current of the PIN diode 19 → smaller, and the variable resistance attenuation circuit 20 attenuation → larger.

Here, the relationship between the phase shifter 11a and the phase shifter 11b, the impedance matching circuit 12, and the variable voltage applied to the voltage application terminal 3-1 will be described in detail.
Assuming that the range of the variable voltage applied to the DC voltage application terminal 3-1 is -10V to -1V, the impedance matching circuit 12 is connected to the phase shifter 11a when the voltage of the voltage application terminal 3-1 is -1V. The capacitor, the coil constant, etc. are adjusted so that the impedance between the capacitor 11b and the capacitor 11b is best matched.

  That is, when the voltage at the voltage application terminal 3-1 is -1V, the passage loss of the phase shifter 11a + phase shifter 11b is minimized, and when the voltage is changed from -1V and the absolute value of the voltage is increased, the deviation from the optimum matching is lost. This causes an increase in the passage loss due to impedance mismatch.

  On the other hand, since the forward voltage of the PIN diode 19 increases at this time, the forward bias current also increases, and the attenuation amount of the variable resistance attenuation circuit 20 decreases. Accordingly, when the phase shifter 11a and the phase shifter 11b are shifted in phase, when the impedance between the stages is mismatched and the passage loss is increased, the attenuation amount of the variable resistance attenuation circuit 20 is reduced, and the shift of FIG. It is possible to suppress the passage loss fluctuation from the signal input terminal 1-1 to the signal output terminal 2-1 in the phase circuit.

  The variable resistance attenuating circuit 20 added in the present embodiment with respect to the conventional phase shifter can be configured with inexpensive and small components such as a resistor, a capacitor, a coil, and a PIN diode. Further, since the supply voltage to the PIN diode is the same as the supply voltage to the phase shifter, no new DC power supply is required. Further, in the present embodiment, an example in which two stages of phase shifters are connected is shown, but when a larger amount of phase shift is required, it may be necessary to use three stages and four stages. In this case, since it is necessary to add an isolator in the conventional circuit, this leads to an increase in cost and an increase in the mounting area. In the case of the present invention, only one variable resistance attenuation circuit is required, and the resistance value is reduced. It is possible to respond by changing only.

  Here, in one embodiment of the phase shift circuit of the present invention, a phase shifter connected in multiple stages, a voltage dividing circuit that divides a DC variable voltage, and a voltage divided by the voltage dividing circuit are applied. And a PIN diode for attenuating a signal passing through the phase shifter.

  According to the above configuration, the signal input to the phase shifter is attenuated by changing the resistance value by changing the forward bias current of the PIN diode, which can be regarded as a pure resistance equivalently when a forward bias voltage is applied. Therefore, it is possible to sufficiently suppress the fluctuation of the passage loss due to the impedance mismatch between the phase shifters during the phase shift.

  Another embodiment of the phase shift circuit of the present invention includes a multi-phase connected phase shifter, a voltage dividing circuit that divides a DC variable voltage, and a voltage dividing circuit that is connected to one of the phase shifters. And a PIN diode for attenuating a signal passing through the phase shifter when a voltage is applied to the cathode electrode (claim 2).

  According to the above configuration, the resistance value between the input terminal and the signal input terminal is changed by changing the forward bias current of the PIN diode, which can be regarded as a pure resistance equivalently when a forward bias voltage is applied. The signal input to the phase shifter can be attenuated, and fluctuations in the passage loss due to impedance mismatch between the phase shifters during the phase shift can be sufficiently suppressed.

  Another embodiment of the phase shift circuit of the present invention includes a phase shifter connected in multiple stages, a voltage dividing circuit that divides a DC variable voltage, a resistor that allows a signal to pass through the phase shifter, and a capacitor at both ends of the resistor. And a PIN diode for attenuating an input signal when the voltage divided by the voltage dividing circuit is applied to the cathode electrode. 3).

  According to the above configuration, the combined resistance value between the input terminal and the signal input terminal is changed by changing the forward bias current of the PIN diode that can be regarded as a pure resistance equivalently when a forward bias voltage is applied. Thus, the signal input to the phase shifter can be attenuated, and fluctuations in the passage loss due to impedance mismatch between the phase shifters during the phase shift can be sufficiently suppressed.

  Another embodiment of the phase shift circuit of the present invention is characterized in that, in addition to the above configuration, the DC variable voltage of the voltage divider circuit is common to the power supply voltage of the phase shifter.

  According to the above configuration, since the input voltage of the voltage dividing circuit is common with the power supply voltage of the phase shifter, it is not necessary to provide a new power supply, and the size can be reduced.

  In another embodiment of the phase shift circuit of the present invention, in addition to the above configuration, a high frequency choke coil is inserted between the anode electrode of the PIN diode and the ground, and between the cathode electrode of the PIN diode and the voltage dividing circuit, respectively. (Claim 5).

  According to the above configuration, since the high frequency choke coil is inserted between the anode electrode of the PIN diode and the ground, and between the cathode electrode of the PIN diode and the voltage dividing circuit, the high frequency signal from the input terminal is transferred to the PIN diode. And the fluctuation of the passage loss can be more sufficiently suppressed.

  In another embodiment according to the phase shift circuit of the present invention, in addition to the above-described configuration, the phase shifter synthesizes a high-frequency signal phase-shifted by the variable capacitance element in phase with a 90-degree 3 dB hybrid, and inputs and outputs It is a reflection type phase shifter which isolates the above (claim 6).

  In another embodiment of the phase shift circuit of the present invention, in addition to the above-described configuration, the phase shifter performs in-phase synthesis of the high-frequency signal phase-shifted by the variable capacitance element by the circulator, and isolates the input end and the output end. It is a reflection type phase shifter which performs (claim 7).

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

FIG. 1 shows an embodiment of a circuit diagram of a phase shift circuit according to the present invention.
〔Constitution〕
A variable resistance attenuation circuit 20 composed of a PIN diode is mounted in order to absorb a passage loss fluctuation accompanying a phase shifter stage impedance mismatch at the time of phase shift. An impedance matching circuit 12 including a capacitor, a coil, and a distributed constant circuit is provided between the stages of the phase shifter 11a and the phase shifter 11b constituting the multi-stage (two stages in FIG. 1 is not limited). Is implemented.

  A variable voltage is supplied from the DC voltage application terminal 3-1 to each of the phase shifters 11a and 11b, and the phase is shifted by the phase shifter 11a and the phase shifter 11b due to the voltage change. At the same time, the variable DC voltage from the DC voltage application terminal 3-1 is stepped down to an appropriate voltage by the voltage dividing resistors 13 and 14, and is supplied to the cathode electrode of the PIN diode 19 through the RF choke coil 17b. The anode electrode of the PIN diode 19 is grounded via the RF choke coil 17a. Reference numerals 18a and 18b denote DC voltage blocking capacitors, which select capacitance values having sufficiently low impedance at the frequency of the high-frequency signal to be used.

Here, the impedance Z of the capacitor is expressed by the equation Z = 1 / (2πfc) where f is the frequency and C is the capacitance of the capacitor, and the impedance decreases as the frequency increases. However, it is considered that an actual capacitor has an L component (parasitic inductance component) determined from its physical dimensions, and equivalently, a capacitor and a coil are connected in series as shown in FIG.
FIG. 5 is an equivalent circuit of an actual capacitor.

The series resonance by C (capacitance) and L (inductance) minimizes the impedance at the self-resonant frequency f = 1 / (2π√ (L × C)), and the frequency is higher due to the inductance component at higher frequencies. As shown, the impedance increases (see FIG. 6).
FIG. 6 is a diagram showing the frequency-impedance characteristics of an actual capacitor, where the horizontal axis is the frequency axis and the vertical axis is the impedance axis.

Since the inductance of a chip capacitor of 1608 size (1.6 mm × 0.8 mm) that is generally used is about 0.8 nH, for example, when the high-frequency signal is 2 GHz, 2e9 = 1 / (2π√ (0.8e− 9 × C)), the impedance is minimized at C = 7.9 pF.
However, since a capacitor with an odd capacitance value such as 7.9 pF is not commercially available, a capacitor such as 8 pF is used when the frequency of the high-frequency signal is 2 GHz.

  When the forward bias current of the PIN diode 19 is changed to be regarded as a variable resistor, a variable resistance attenuation circuit 20 is formed by a combination of the resistor 15 and the resistor 16. The passage loss fluctuation caused by the interstage impedance mismatch at the time of the phase shift of the phase shifter 11a and the phase shifter 11b is absorbed by the attenuation change of the variable resistance attenuation circuit 20.

[Operation]
The operation of the embodiment will be described with reference to FIG.
A variable DC voltage is supplied from the DC voltage application terminal 3-1 to the phase shifter 11a and the phase shifter 11b. As shown in FIG. 8, the reflection type phase shifter applies a reverse bias to the varactor diode 7a and the varactor diode 7b and changes the voltage to change the reflection phase, thereby realizing the phase shift.
In this embodiment, since it is assumed that the cathode electrode of the varactor diode is grounded and a variable voltage is applied to the anode electrode side, a negative voltage is applied to the phase shifter from the DC voltage application terminal 3-1. The Conversely, when the anode electrode of the varactor diode is grounded, a positive voltage is applied to the phase shifter from the DC voltage application terminal 3-1. An impedance matching circuit 12 including a capacitor, a coil, and a distributed constant circuit is mounted between the phase shifter 11a and the phase shifter 11b. By optimizing the capacitor, coil constant, and distributed constant circuit structure of the impedance matching circuit 12, it is possible to achieve interstage impedance matching when the voltage applied to the phase shifter is a fixed value.

  However, when the voltage applied to the phase shifter is changed due to the phase shift, the input / output impedance per stage of the phase shifter changes not a little, so that a shift occurs in the interstage impedance matching in multiple stages. When the impedance mismatch between the stages occurs, the high frequency signal power is reflected at the location, and this appears as an increase in passage loss. As an example, assuming that the variable DC voltage of the DC voltage application terminal 3-1 is in the range of -10V to -1V, the impedance matching circuit 12 has a capacitor and coil so as to be optimal when the voltage absolute value is the smallest -1V. Adjust the constants. When the voltage is changed to the −10V side for phase shift, the interstage impedance deviates from the matching state, resulting in an increase in passage loss.

  On the other hand, the variable DC voltage at the DC voltage application terminal 3 is applied to the phase shifter 11a and the phase shifter 11b, and at the same time, is stepped down to an appropriate voltage by the voltage dividing resistor 13 and the voltage dividing resistor 14 (the resistance of the resistor 13). When the value is R13, the resistance value of the resistor 14 is R14, and the voltage of the DC voltage application terminal 3-1 is Vi, the voltage Vo between the resistors 13 and 14 is Vi * [R14 / (R13 + R14)]. And applied to the cathode electrode of the PIN diode 19 via the RF choke coil 17b. The anode electrode of the PIN diode 19 is grounded via the RF choke coil 17a.

  Here, 18a and 18b are DC voltage blocking capacitors, and a capacitance value having sufficiently low impedance is selected at the frequency of the signal to be used. The PIN diode 19 is a variable resistance element that can be equivalently regarded as a pure resistance when a forward bias voltage is applied, and whose resistance value can be changed by changing a forward bias current. The resistance value decreases as the forward bias current increases.

  In this embodiment, the voltage applied to the DC voltage application terminal 3-1 is a negative voltage, the anode electrode of the PIN diode 19 is grounded, the negative voltage is applied to the cathode electrode, that is, the forward bias voltage is applied. By changing this negative voltage, it can be regarded as a variable resistor. From the simulation results described above, the variable resistance attenuation circuit 20 composed of the PIN diode 19 exhibits a characteristic that the forward bias current of the PIN diode 19 is small and the attenuation amount of the variable resistance attenuation circuit 20 is large. In other words, when the forward bias current of the PIN diode 19 is large, the attenuation amount of the variable resistance attenuation circuit 20 becomes small.

  Now, since the voltage at the DC voltage application terminal 3-1 is changed from -1V to -10V in the direction in which the absolute value increases, the forward voltage of the PIN diode 19 increases at this time, and the forward bias current increases. The attenuation amount of the variable resistance attenuation circuit 20 becomes small.

  From the above, when the phase shifter 11a and the phase shifter 11b are shifted in phase, when the impedance between the stages is mismatched and the passage loss is increased, the attenuation amount of the variable resistance attenuation circuit 20 is decreased, and the phase shifter 11a + Absorbs the increase in passage loss of the phase shifter 11b. That is, it is possible to suppress the passage loss fluctuation from the signal input terminal 1-1 to the signal output terminal 2-1 in FIG.

[Explanation of effects]
The first effect is that the passage loss fluctuation of the multistage phase shifter can be suppressed when the phase changes.
The second effect is that a multi-stage phase shifter with small passage loss fluctuation can be realized at a low price.
The third effect is that a multistage phase shifter with small fluctuations in passage loss can be realized with a small mounting area.
The fourth effect is that even if the number of stages of the phase shifter is increased, the effect of small fluctuation of the phase shifter passage loss can be maintained without increasing the number of components other than the phase shifter section.

FIG. 7 shows another embodiment of the phase shifter used in the phase shift circuit according to the present invention.
FIG. 1 shows an application to a reflection type phase shifter using a 90 degree 3 dB hybrid as an embodiment of the present invention, but a circulator 22 is used instead of the 90 degree 3 dB hybrid 6 as shown in FIG. It can also be applied to a reflective phase shifter.
The phase shifter shown in FIG. 7 includes a circulator 22, capacitors 4a and 4b respectively inserted between an input terminal PA (left end in the figure) of the circulator 22 and an output terminal PC, a control terminal PB of the circulator 22, and a ground. A capacitor 8 and a resistor 9 inserted in series between the control terminal PB and the ground, the varactor diode 7 connected so that the cathode electrode is grounded, the anode electrode of the varactor diode 7 and the control terminal A high-frequency choke coil 5 inserted between the PB and the PB is provided.
That is, the phase shift circuit may be configured by replacing the circuit between the terminal 1-2 and the terminal 2-2 shown in FIG. 7 with the phase shifters 11a and 11b shown in FIG.

  Even in the phase shift circuit using such a phase shifter, the fluctuation of the passage loss due to the impedance mismatch between the phase shifters during the phase shift is sufficiently performed.

  Here, the invention disclosed in Patent Document 1 (Japanese Utility Model Laid-Open No. 2-75801), Patent Document 2 (Japanese Patent Laid-Open No. 8-97602), and Patent Document 3 (Japanese Patent Laid-Open No. 10-256809), and the present application. The difference from the invention is that, in the present invention, the variable attenuation circuit is composed of inexpensive and small parts such as a PIN diode, an RF choke coil, a resistor, and a capacitor, and a plurality of phase shifters are connected by an impedance matching circuit. In addition, the supply voltage to the varactor diode in the variable phase shifter and the supply voltage to the PIN diode in the variable resistance attenuation circuit are supplied from the common DC voltage application terminal 3-1 through a voltage dividing resistor or the like. (There is no need for two types of voltage terminals for varactor diodes and PIN diodes.)

  The present invention is applicable to a microwave radio communication device and a mobile communication radio communication device.

It is a circuit diagram showing one embodiment of a phase shift circuit concerning the present invention. (A)-(d) is a figure which shows an example of the impedance matching circuit 12 used for the phase shift circuit shown in FIG. It is an equivalent circuit of the variable resistance attenuation circuit used for the phase shift circuit shown in FIG. It is a figure which shows the simulation result of the passage loss characteristic of the variable resistance attenuation circuit used for the phase shift circuit shown in FIG. It is an equivalent circuit of an actual capacitor. It is a figure which shows the frequency-impedance characteristic of an actual capacitor | condenser. It is another Example of the phase shifter used for the phase shift circuit which concerns on this invention. It is a circuit diagram which shows the prior art example of a 1 step | paragraph reflection type phase shifter. It is a circuit diagram which shows the prior art example of a multistage reflection type phase shifter.

Explanation of symbols

1-1, 1-2, 1-3, 1-4 signal input terminals 2-1, 2-2, 2-3, 2-4 signal output terminals 3-1, 3-2, 3-3, 3- 4 DC voltage application terminal 11a, 11b Phase shifter 12 Impedance matching circuit 13, 14, 15, 16 Resistance 17a, 17b RF choke coil 18a, 18b Capacitor 19 PIN diode 20 Variable resistance attenuation circuit

Claims (7)

  A phase shifter connected in multiple stages, a voltage dividing circuit that divides a DC variable voltage, and a PIN diode that attenuates a signal that passes through the phase shifter when a voltage divided by the voltage dividing circuit is applied. A phase shift circuit characterized by that.   A phase shifter connected in multiple stages, a voltage dividing circuit that divides a DC variable voltage, and a voltage that is connected to one of the phase shifters and divided by the voltage dividing circuit is applied to the cathode electrode. A phase shift circuit comprising a PIN diode for attenuating a signal passing through a phase shifter.   A phase shifter connected in multiple stages, a voltage dividing circuit that divides a DC variable voltage, a resistor that passes a signal through the phase shifter, and a cathode electrode and an anode electrode that are connected to both ends of the resistor via capacitors. And a PIN diode that attenuates an input signal when the voltage divided by the voltage dividing circuit is applied to the cathode electrode.   4. The phase shift circuit according to claim 1, wherein the DC variable voltage of the voltage dividing circuit is common to a power supply voltage of the phase shifter. 5.   5. The phase shift circuit according to claim 3, wherein a high frequency choke coil is inserted between the anode electrode of the PIN diode and the ground, and between the cathode electrode of the PIN diode and the voltage dividing circuit. .   2. The phase shifter according to claim 1, wherein the phase shifter is a reflection type phase shifter that in-phase-synthesizes a signal phase-shifted by a variable capacitance element with a 90 degree 3 dB hybrid and isolates an input end and an output end. 6. The phase shift circuit according to any one of items 1 to 5.   6. The reflection phase shifter according to claim 1, wherein the phase shifter is a reflection type phase shifter that in-phase-synthesizes a signal phase-shifted by a variable capacitance element by a circulator and isolates an input end and an output end. The phase shift circuit of any one of Claims.

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