JPH0399509A - Phase shifter - Google Patents

Abstract

PURPOSE:To improve the reflection characteristic of a phase shifter by connecting resistances to respective capacitors of an LPF and an HPF, and improving the reflection characteristic. CONSTITUTION:The input signal from an input terminal 1 is outputted to an output terminal 11 through a radio wave propagation path having an LPF 31 or an HPF 32 selected by a switch 20 of the phase shifter. Resistances 37a and 37b are connected to capacitors 23a and 23b of the LPF 31 consisting of an inductance line 21 and first capacitors 23a and 23b to improve the reflection characteristic of the LPF 31. The reflection characteristic of the HPF 32 is improved by series resistances 37c and 37d in the same manner, and the reflection characteristic of the phase shifter is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improving the reflection characteristics of a phase shifter.

[Conventional technology]

Figure 6 shows 2 For example, C0W, fluxling
, @5-BandPhase 5hifter usi
ng Monolithic GaAe 0i-rcu
its '1EEE International'l
Elolid-BtateClrcuit C! onf
FIG. 2 is a circuit configuration diagram showing a conventional phase shifter shown in ERENCE J982 PF, 134-135.

In the figure, (1) is the input terminal, (2) is the first FET
.

(3) (41(5) is the first IF Et T
(2) first drain electrode, first source electrode, and first gate electrode;

(6) is the second 71! ! T, (71 (81 (9) is the second F E T (61 second drain electrode, second
The source electrode of , the second gate electrode, a. is the input terminal (1
) connected to the first FF1T+2) and the second IP
The first single-pole double-throw switch (hereinafter abbreviated as EIPDT switch), (1υ
is an output terminal, and 13 is the third FEI T.

C3H (1!9 is the third of the third F11iTα)
a drain electrode, a third source electrode, and a third gate electrode.

House e is the 4th FIT, αηα barrel α is the 4th F K T
(4th drain electrode, 4th source electrode, 4th gate electrode of ll, (4) is output terminal C11), which is connected to the 3rd F11fTα2 and the 4th FITQe. The second 8 composed of K T H
The PDT switch, Qυ, is the first inductor line connected between the first source electrode (4) of the first PEi T (2+) and the third source polarization a- of the third FITQ. , r22J is the grounding conductor, (23a) (25
b) is the first capacitor whose one end is connected to the first inductor line I2υ and the other end is connected to the grounding conductor (2); (24a) (24b) is the second F El
! The second source electrode (8) of T (6) and the fourth FI
The second capacitor, 12!9, which is connected in series with the fourth north pole (11) of TQ Roku, has one end connected to the midpoint of the second capacitor (24a) (24b),
The second conductor line (26a) to (26d) whose other end is connected to the grounding conductor @ is the first line. Second.
3rd degree and 4th bias terminal, (27a) ~
(27d) is a bias line, (28a) to (28
In d), one end is connected to the bias lines (27a) to (27a), respectively.
7d) through the 1st and 2nd. Third. and a bias circuit capacitor which is connected to the fourth bias terminals (26a) to (26d) and whose other ends are respectively connected to the grounding conductor @.

(29a) to (29d) have one end connected to the first gate electrode (5), second gate electrode (9), third gate electrode α9°, and fourth gate electrode 0, respectively, and the other end are bias circuit capacitors (28a) to (2), respectively.
The bias resistor connected to &l) is the semiconductor substrate on which the above circuit is formed as a microwave IC. Here, the first gate electrode (5), the second gate electrode (9), the third gate electrode 0, and the fourth gate electrode 0! Second. Third. and.

A bias voltage is applied via the fourth bias terminals (26a) to (26d) or is necessary at this time CIJ
The turn circuit is omitted from illustration here. In addition, the first inductor circuit line Cυ and the first capacitor (23a
) (23b), a low-pass filter 10 (hereinafter abbreviated as LPF) is formed, and the second capacitor (24a) (24b) and the second inductor line (G) A high-pass filter 02 (hereinafter abbreviated as HPF) is formed. Also here.

For T, PF', and HPF, the element values of each of the above reactance elements are set so that the required frequency is the pass band.

Next, the operation will be explained.

FIG. 7 is a schematic diagram for explaining the operating principle of the conventional phase shifter, and (1) the screen αυmciυ02 is the same as that shown in FIG. A conventional phase shifter is configured as shown in the figure, and takes advantage of the fact that a phase lag occurs in the passband of LPFC1υ and a phase lead occurs in the passband of HPFT33. By switching to the HPF'03 side, the required amount of phase shift is obtained. In addition,
Here, in addition to the first EIPDT switch α port, the second 5P
By providing a DT switch (to), the circuit elements making up the phase shifter and the external circuit into which the phase shifter is inserted are completely separated, allowing them to operate without affecting each other. be.

8 is an equivalent circuit diagram of the conventional phase shifter shown in FIG. 6, and each reference numeral in FIG. 99 indicates the same thing as in FIG. 6.

In the figure, the first gate electrode (5) of the first FET (2) and the third gate electrode α9 of the third FITQ2
The bias voltage applied to and is Ov.

A case will be described in which the bias voltage applied to the second gate electrode (9) of the second FET (61) and the fourth gate electrode a9 of the fourth FlnTa[9 is a pinch-off voltage. A current flows through the first FET (21) and the third FKT113, which can be equivalently expressed as a resistance, and the second FHT(6) and the fourth F'
1! i T (a depletion layer is formed in i5, blocking the current, and it can be equivalently represented by a capacitor. Therefore, at the required frequency, the impedance exhibited by the capacitor should be made sufficiently large, and the value of the above resistance should be made sufficiently large. If you set it to be small, the first 8PDT switch α
1 and the second S PDT switch (1) are LPII'(i
This is equivalent to switching to the υ side, p, I,
The PFOv side is in a passing state, and the HPFQ3 side is in a blocking state.

In this case, the radio waves incident from input terminal (1) are:

By passing through the LPF (lυ), a 9 phase delay is generated, which is applied to the output terminal (11+).On the other hand, the bias voltage applied to the four FITs is reversed from the above, and the first FK
The bias voltage applied to the first gate electrode (5) of T
Let OV be the bias voltage applied to the gate electrode (9) of and the first gate electrode (II) of the fourth FEETαe.

Contrary to the above case, the first 8FD? Switch (11)
This is equivalent to the second 5PDT switch being switched to the HPF (to) side, and the LPPCIυ side is in the blocking state and the HPF (to) side is in the passing state. In this case, the radio wave incident from the input terminal +11 passes through the HPF (to), causes a two-phase lead, and is delivered to the output terminal αυ. Therefore, in a conventional phase shifter.

By switching the bias voltage applied to the four PETs and switching the first 5PDT switch α1 and the second 5PI T switch (1), a phase shift of 1 between the input and output terminals can be achieved.
can be changed.

As mentioned above, this type of phase shifter has I, PF (lυ
A two-pass phase difference can be obtained by switching the radio wave propagation path between the side and the HPIF (to) side, and by cascading these phase shifters in multiple stages, the required phase shift can be achieved. quantity can be achieved.

FIG. 9 is a configuration explanatory diagram showing, for example, a 2-bit phase shifter in which the above-mentioned phase shifters are connected in two stages.
The first phase shifter has a passing phase difference of 145 degrees on the η side and +45 degrees on the HPIF (to) side, (33b) is an LP
The second phase shifter has a passing phase difference of 190 degrees on the FC3υ side and +90 degrees on the HPP@ side, (b) shows the first phase shifter (55a) and the second phase shifter ( 531)) and other lines are similar to those shown in FIG. In the figure, the first 5 of the first phase shifter (33a)
The PDT switch α and the second 5PDT switch (1) are on the LPF01) side, the second phase shifter (33b) and the first
8 PDT switch members and a second EIPIIT switch (
1) shows the case where the HPF is switched to the (to) side and the passing phase difference between the input and output terminals is +45 degrees. Note that the first 8 PDTs of the first phase shifter (15a)
switch a [and the second 5PDT switch (to), and the first 5PDT switch O of the second phase shifter (5sb)
By switching the 1st and 2nd B F D and T switch (2), the passing phase difference between the input and output terminals is 145 degrees, +13
5 degrees, -135 degrees are obtained.

Here, when connecting the first phase shifter (53a) and the second phase shifter (331) as described above, the line to be connected (
(b) Reflection occurs between the phase shifter and the phase shifter, and reflection also occurs between the phase shifter and the external circuit into which the phase shifter is inserted, causing a phase shift amount error, so impedance matching is required. Become.

FIG. 10 shows an explanatory diagram for explaining a conventional means for improving reflection characteristics. Figure 10(a) shows the output terminal σD of the phase shifter.
This is a configuration diagram in which a matching circuit (35a) consisting of a reactance element is inserted in the part.

FIG. 10(1)) is a configuration diagram in which matching circuits (35b) (55c) each consisting of a reactance element are inserted in the radio wave propagation path between the LPFQD side and the HPF (to) side of the phase shifter. In the figure, matching circuits (55a) (55b) (
35c) is the same as that shown in FIG. 1st
As shown in FIG.
Against 3.

Matching circuit (35a) consisting of reactance element (+5
b) Impedance matching is achieved by inserting (356).

[Problem to be solved by the invention]

Since the conventional microwave semiconductor phase shifter is configured as described above, an inductive element is required to configure the LPF and HPF. In the microwave band, to obtain the required inductance.

A high-impedance line is formed into a meandering or spiral shape to form an inductive element, but because the line is long, it has its own resistance. This resistance is LPF', HP
It intervenes as a reflection coefficient determining element related to the reflection characteristics of IF, and in this reflection coefficient.

Reflection occurs because the reflection coefficient becomes too large to ignore due to the relationship with 50Ω, which is selected as the source impedance and load impedance in a normal circuit. Reflection caused by this resistance cannot be canceled by the capacitive elements forming the LPF and EPF in the conventional configuration. For this reason, when combined as a multi-pit phase shifter as described above, problems have arisen, such as an increase in phase shift amount error due to the influence of multiple reflections. In response to this, conventional measures have been taken to improve the reflection characteristics as explained in FIG. 10 above. However, in the configuration shown in FIG. 10(a), the matching circuit (35a) is common to the radio wave propagation path on the LPFOυ side and the IFF side.

There is a problem that impedance matching cannot be achieved optimally for both, resulting in incomplete impedance matching. In addition, in the configuration shown in FIG. 10(b), the matching circuits (35b) (35c) that are inserted or made up of actance elements and the LPFClυ and HPF (to) made of reactance elements influence each other, and the I , PFOI) and HPIII, which makes adjustment very difficult.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a phase shifter with good reflection characteristics.

[Means to solve the problem]

In the phase shifter according to the present invention, an input terminal;

between the output terminal and the above input terminal and output terminal.

a radio wave propagation path having a low-pass filter consisting of an inductor and a capacitor; a radio wave propagation path having a high-pass filter consisting of an inductor and a capacitor; and means for selecting one of the two radio wave propagation paths. Prepare,
A resistor for improving reflection characteristics is connected in series or parallel to the capacitor constituting the low-pass filter, and a resistor for improving reflection characteristics is connected in series or parallel to the capacitor constituting the high-pass filter. It is made by connecting a resistor.

[Effect]

In this invention, a resistor connected in series or in parallel to a capacitor constituting an LPF (3υ), and

The resistors connected in series or in parallel with the capacitors constituting HP F C3a are LPFCIυ and HP
There exists a value that acts to cancel out the increase in the reflection coefficient caused by the resistance of inductive elements such as high impedance lines that make up the And the reflection of the radio wave propagation path on the HPF'Gl side is reduced.

〔Example〕

FIG. 1 is a circuit diagram showing a phase shifter according to an embodiment of the present invention. In this embodiment, the microwave semiconductor phase shifter (/c) similar to the conventional example will be explained. In the figure, (to) is connected to the ground conductor on the back side of the semiconductor substrate (to) instead of the ground conductor @. Via hole for grounding (57a)
, (37b) are the first and second resistors connected in parallel to the capacitor constituting the LPFCIυ to improve the reflection characteristics, (37c) and (37d) are the HPF
(to) third and fourth resistors for improving reflection characteristics connected in series to the capacitor forming the capacitor.

ill~Qυ and (c)~C3 are the same as the conventional phase shifter shown in FIG. 2 is an equivalent circuit diagram of the phase shifter shown in FIG. 1. Each symbol in FIG.
Shows the same thing as the figure. Here, the first and second resistors (37a) (71)) have one end connected to the via hole (towards
The other end is electrically connected to the first inductor line Qυ constituting the spiral inductor, and is connected in parallel to the first capacitors (23a) (23b). On the other hand, the third and fourth resistors (37c)
(37d) has one end connected to the second capacitor (24a) (2
4b), the other end thereof is electrically connected to a second inductor line (to) constituting a four-spiral inductor, and is connected in series to the second capacitors (24a) (24b). It should be noted that in FIGS. 1 and 2, the illustration of the DC return circuit is omitted as in the conventional example. Here, the reason why the high impedance line is formed into a spiral shape to form a spiral inductor is to realize a large inductance with a small pattern occupation area. Also, LPFOυ and HPF (to) are the impedance seen from the input terminal il+ side and the output terminal α
It is formed symmetrically in a π-shape or a T-shape so that the impedance seen from the υ side is equal.

Note that the operating principle and general operation of the phase shifter of the present invention are the same as those of the conventional phase shifter shown in FIG. 6, and a description thereof will be omitted.

Next, the first. Second. Third and fourth resistors (37a) (3
7b) (37c) The effect of improving the reflection characteristics by loading (37d), that is, the voltage reflection coefficient of the radio wave propagation path on the LPF (+υ side and HPFGa side) is reduced to zero by resistor loading in the above arrangement. The existence of a resistance value that leads to FIG. 4(a) shows the state before resistor loading, and FIG. 3(1)) and FIG. 4(b) show the state after resistor loading. To simplify the explanation, the residual resistance components of the first capacitors (23a) (2sb) and the second capacitors (24a) (24b) are not shown here, and in FIG. The resistance component R of the inductor line 12υ
1 and 12. as first and second resistors (57a) (37b). In Fig. 4, the resistance component R3 of the second inductor line (c) constituting the spiral inductor and R as the third and R4 resistances (370) (57d) are shown.
Only 4 is shown. Also, the first B PI)? The switch αQ and the second 5PI) T switch wire are almost short-circuited and are omitted.

The following was determined based on the above equivalent circuit diagram. The voltage reflection coefficient F in each case is shown.

Here, zO is '1 source invader/s, and.

is the load impedance.

In the case of FIG. 3(a), the result is 9th order equation (11).

In the case of Figure 3 (1)).

It becomes as shown in the following equation (2).

In the case of FIG. 4(a).

It becomes as shown in the following equation (3).

In the case of FIG. 4(b).

The following equation (4) is obtained.

Therefore.

(1) Equation.

From equation (3).

Voltage before resistor loading The morphism coefficient does not become zero.

rl.

Voltage reflection of r3 occurs. Sign.

Also.

(2) Equation.

From equation (4).

R2 and R4, where rl and r4 are zero, are determined as shown in the following equations (5) and (6), respectively.

Therefore.

If R2 and R4 are selected to have values expressed by equations (5) and (6), respectively, reflections due to R1 and R3 can be canceled.

As explained above, by loading a resistor in a π-type or T-type with the inductor line,
5. LPFC! There is a resistance value that brings the voltage reflection coefficient of the radio wave propagation path on the υ side and HPFC (3 side) to zero, which can cancel out the reflection caused by the resistance component of the inductor line and improve the reflection characteristics of the phase shifter. Effects can be obtained.

In addition, in order to briefly explain that 9 effects can be obtained, some of the circuit components that form the radio wave propagation path are omitted and the thinking process is emphasized, but in reality, R2 and R4 are When designing.

How many circuits are used, including all related circuit components?1
As with normal circuit design, it is common to use a computer to analyze and find a solution.

Further, in the embodiment shown in FIG. 5(a), the first capacitor (25a) (25b) l the second capacitor (2
4a) is a circuit configuration diagram showing a circuit configuration in which a resistor is connected in series to (24b), which has the same effect as the above embodiment.

Furthermore, in the embodiment shown in FIG. 5 (1+), the first capacitor (25a) (23b), the second capacitor (2
4a) is a circuit configuration diagram showing a circuit configuration in which a resistor is connected in parallel to (24b), which has the same effect as the above embodiment. Note that when resistors are connected in parallel as in this example, a resistor with a larger resistance value is formed than a resistor connected in series, so the amount of error in the tolerance setting accuracy of the resistance value is large. Nasi.

This has the effect of making it easier to manufacture a microwave IC circuit.

Note that variations in the circuit configuration due to the above-mentioned resistor connection method are determined by serial-parallel conversion in circuit theory, and are not limited to the above-mentioned configuration.

In addition, in the phase shifter according to the present invention, since the reflection characteristics of the phase shifter are improved inside the phase shifter for each stage, multi-stage connection is easily possible, good reflection characteristics can be obtained, and the phase shifter can be easily connected in multiple stages. This has the effect of reducing quantity errors.

Incidentally, in the above embodiment, a microwave semiconductor phase shifter with 10 microwave circuits was shown as an example, but it goes without saying that the present invention is not limited to this and can be applied to a phase shifter that obtains a phase shift amount by selecting an LPF or an IFF. stomach.

〔Effect of the invention〕

As described above, according to the present invention, a resistor for improving reflection characteristics is connected in series or parallel to a capacitor constituting a low-pass filter, and.

A resistor is connected in series or parallel to the capacitor that makes up the high-pass filter to improve the reflection characteristics.
This has the effect of improving the reflection characteristics of the phase shifter.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing a phase shifter according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the phase shifter shown in FIG.
The figure is an equivalent circuit diagram representing the LPIF, Figure 4 is an equivalent circuit diagram representing the HPF, and Figure 5 (a) is the first capacitor (2
3a) (23b), second capacitor (24a)
(24b) is a circuit configuration diagram showing a circuit configuration in which a resistor is connected in series, FIG. 5(b) is the first capacitor (25a)
(231)) # Second capacitor (24a) (2
FIG. 3 is a circuit configuration diagram showing a circuit configuration in which a resistor is connected in parallel to ab). FIG. 6 is a circuit configuration diagram showing a conventional phase shifter, FIG. 7 is a schematic diagram for explaining the operating principle of the conventional phase shifter, FIG. 8 is an equivalent circuit diagram of the conventional phase shifter, and FIG. FIG. 9 is a configuration explanatory diagram showing a 4-bit phase shifter connected in two stages in cascade, and FIG. 10 is an explanatory diagram for explaining a conventional means for improving reflection characteristics. In the figure, (1) is the input terminal, (2) is the first FK
T. (3) is the first drain/electrode, and (4) is the first source electrode. (5) is the first gate electrode, (6) is the second FE! T,
+7+ is the second drain' polarization, (8) is the second source electrode, (9) is the second gate electrode, ([The scratch is the first 5P
DT switch, (lυ is the output terminal, a2 is the third terminal)
K T, (lJu third drain electrode, (14+ is the third source electrode, G is the third gate electrode, (te is the fourth pbT, (17) is the fourth drain electrode, 0 seconds is the third 4 is the source electrode, 01 is the fourth gate electrode, ■ is the second 5PDT switch, all is the first inductor line, and (23b) is the grounding conductor. (25a) (23b) is the first capacitor, (2
4a) (24b) is the second capacitor, (C) is the second inductor line, (2da) to (2dd) are bias terminals, (27a) to (27d) are bias lines, (28a) to ( 28d) is a bias circuit capacitor, (29a) to (29d) are bias resistors, (to) is a semiconductor substrate, Gυ is L P F, (to) is H
PF, (35a) is the first phase shifter, (ssb)
is the second phase shifter, (b) is the line, (to) is the matching circuit, (
) is Via Hall. (37a) to (s7a) are resistances. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] An input terminal, an output terminal, and a radio wave propagation path having a low-pass filter consisting of an inductor and a capacitor, and a high-pass filter consisting of an inductor and a capacitor, between the input terminal and the output terminal. In a phase shifter equipped with a radio wave propagation path and means for selecting one of the two radio wave propagation paths, a resistor for improving reflection characteristics is provided in series or in parallel with the capacitor constituting the low-pass filter. 1. A phase shifter, further comprising a resistor connected in series or parallel to a capacitor constituting the high-pass filter for improving reflection characteristics.