JP3178189B2 - Ferroelectric transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric transmission line constituting a microwave circuit.

[0002]

2. Description of the Related Art In recent years, by combining a microwave transmission line and a semiconductor diode formed on a paraelectric material, a voltage-controllable filter circuit, a voltage-controllable resonance circuit, a modulation circuit, a detection circuit, and a frequency conversion circuit have been developed. And other microwave circuits.

Hereinafter, a microwave circuit using a conventional semiconductor diode will be described. FIG. 4A is a perspective view of a typical microwave transmission line. In FIG. 2A, reference numeral 41 denotes a paraelectric substrate, reference numeral 42 denotes a conductor pattern, and reference numeral 43 denotes a ground conductor. FIG. 1B is a plan view of a voltage control filter circuit realized by combining a microwave transmission line and a semiconductor diode.

The voltage control filter circuit 44 is constructed by connecting a varactor diode 45 to a part of a half-wavelength transmission line 46, and the half-wavelength transmission line 46 is electric-field-coupled to the preceding and following transmission lines. , A band-pass filter for transmitting microwaves of a target frequency. The control voltage is supplied through a microwave choke line 47 that is a combination of quarter-wave transmission lines. The center frequency is controlled by utilizing the fact that the equivalent line length of the varactor diode 45 changes according to the applied voltage.

In addition to the voltage control filter having the above-described configuration, varactor diodes, PIN diodes, Schottky diodes, and the like are used for microwave circuits such as a voltage control resonance circuit, a modulation circuit, a detection circuit, and a frequency conversion circuit. It is configured.

[0006]

However, in the above-mentioned conventional configuration, there is a problem that a microwave circuit becomes expensive because a semiconductor diode is required for each circuit. In particular, there is a problem that as the frequency of the microwave increases, the influence of the parasitic reactance component when mounting the semiconductor diode increases, which complicates the design and manufacture of the high-frequency circuit.

The present invention solves the above-mentioned conventional problems. By forming a microwave transmission line using only a substrate material and a conductor pattern without using a semiconductor diode, the cost can be reduced and the parasitic reactance component can be reduced. It is an object of the present invention to provide various microwave circuits which are not affected by the above.

[0008]

In order to achieve this object, a ferroelectric transmission line according to the present invention is provided with a ferroelectric material whose permittivity changes according to the magnitude of an applied electric field on a ground conductor.
A transmission line for propagating microwaves on the ferroelectric material is formed by a conductor pattern, and by changing a dielectric constant of the ferroelectric material by a voltage applied to the conductor pattern, the characteristics of the microwave are changed. It is characterized by being changed.

[0009]

According to the above structure, the on-line wavelength shortening rate, that is, the equivalent line length can be controlled by changing the dielectric constant of the ferroelectric substance. A resonance circuit can be configured. Also, by changing the dielectric constant of the ferroelectric, it is possible to control the characteristic impedance of the line, that is, the signal source impedance seen from the load line,
The conductor pattern can form, for example, a modulation circuit, a detection circuit, and a frequency conversion circuit.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show an embodiment of a ferroelectric transmission line according to the present invention. FIG. 1A is a configuration diagram of a ferroelectric transmission line, and FIG. It represents the dielectric polarization characteristic, that is, the nonlinear dielectric constant.

In FIG. 1A, reference numeral 1 denotes a ferroelectric substrate material;
Denotes a paraelectric substrate material, 3 denotes a conductor pattern, and 4 denotes a ground conductor. Arrow 5 indicates the electric field generated by the transmitted microwave signal, and arrow 6 indicates the electric field generated by the bias DC voltage, and indicates that the two electric fields are in the same direction. Generally, the dielectric constant of a ferroelectric is a tensor quantity, and as shown in FIG. 3B, the dielectric constant of the ferroelectric substrate 1 measured in the direction of the electric field on the horizontal axis is represented by the slope of a curve and applied. This shows that the dielectric constant changes depending on the magnitude of the electric field. The ferroelectric transmission line of the present invention effectively utilizes the nonlinear dielectric constant of a ferroelectric, and specific examples of various microwave circuits will be described below.

FIG. 2A is an embodiment applied to a voltage control filter circuit, FIG. 2B is an embodiment applied to a voltage control resonance circuit, and FIG. 3A is an embodiment applied to a modulation circuit. FIG. 1B shows an embodiment applied to a detection circuit, and FIG. 2C shows an embodiment applied to a frequency conversion circuit.

The voltage control filter circuit 1 shown in FIG.
Reference numeral 1 denotes a band-pass filter having a center line 12 to which a control signal is applied and a center frequency of a microwave having a line length of exactly １ ／ wavelength, and a conductor pattern formed on the ferroelectric substrate region A. It is formed in. The control voltage is 1 /
The power is supplied through a microwave choke line 13 composed of a combination of four wavelength transmission lines, and the choke line 13 is formed in the paraelectric region B so that the choke effect is not deteriorated by a control voltage.

A microwave whose electric field strength is sufficiently small with respect to the non-linearity of the dielectric constant of the line substrate material is propagated on the center line 12, and the electric field intensity is controlled by the line base as a control signal applied to the center line 12. Use a signal that is large enough to change the dielectric constant of the plate. Using the fact that the wavelength of the microwave on the center line 12 changes depending on the dielectric constant of the line substrate material, the center frequency of the filter can be changed by the control voltage.

The voltage control resonance circuit 14 shown in FIG.
Is a resonance circuit having a microwave whose resonance frequency is such that the line length of the ring-type line 15 to which the control signal is applied is just one wavelength, and its conductor pattern is formed on the ferroelectric substrate region A. . The control voltage is supplied through a microwave choke line 16 composed of a combination of １ ／ wavelength transmission lines. The choke line 16 is formed in the paraelectric region B so that the choke effect is not deteriorated by the control voltage.

On the ring type line 15, a microwave whose electric field intensity is sufficiently small with respect to the nonlinearity of the dielectric constant of the line substrate material is propagated, and the electric field intensity is controlled as a control signal applied to the ring type line. Use a signal that is large enough to change the dielectric constant of the substrate material. Then, similarly to the voltage control filter circuit 11, the ring type line 15
By utilizing the fact that the wavelength of the microwave changes depending on the dielectric constant of the line board material, the resonance frequency can be changed by the control voltage.

Next, the modulation circuit 17 shown in FIG. 3A changes the degree of matching between the input and output by changing the characteristic impedance of the modulation line 18 to which the modulation signal is applied, and transmits the transmitted micro-signal. And the conductor pattern of the ferroelectric substrate region A
Formed above. The modulation signal is supplied through a microwave choke line 19 composed of a combination of quarter-wave transmission lines. The choke line 19 is formed in a paraelectric region B so that the choke effect is not deteriorated by a control voltage. The input and output lines are coupled via a capacitor 20 so that the modulation signal does not affect the input and output lines.

A microwave whose electric field strength is sufficiently small with respect to the non-linearity of the dielectric constant of the line board material is propagated on the center line 18, and the electric field strength is applied to the center line 18 as a modulation signal. If a signal having a magnitude sufficient to change the dielectric constant of the plate material is used, the characteristic impedance of the center line 18 changes according to the dielectric constant of the line board material, and the matching between input and output is used. Can be modulated by the modulation signal to modulate the microwave.

The detection circuit 21 shown in FIG. 2B is connected to the detection line 22 when the characteristic impedance of the detection line 22 to which the detection microwave is applied is different between the positive side and the negative side of the microwave electric field. The detection is performed by utilizing the generation of a low-frequency voltage corresponding to the amplitude of the applied microwave, and the conductor pattern is formed on the ferroelectric substrate region A. The bias voltage is supplied through a microwave choke line 23 formed by a combination of quarter-wave transmission lines. The choke line 23 is formed in the paraelectric region B so that the choke effect is not deteriorated by the control voltage. The line 22 is coupled to the input line a and the matching line b via the capacitor 24 so that the bias voltage d does not affect the input line a and the matching line b.

A microwave whose electric field intensity is large enough to change the dielectric constant of the line substrate material is propagated on the detection line 22 and the dielectric characteristic of the line substrate material is transmitted to the detection line 22. A bias voltage having an electric field strength sufficient to shift to one side is applied. Then, the characteristic impedance of the detection line 22 with respect to the microwave propagating through the line differs between the positive side and the negative side of the microwave electric field, and similarly to the diode detection circuit, the signal source impedance viewed from the detection load has the positive polarity of the microwave. The difference between the negative side and the negative side enables microwave detection.

The frequency conversion circuit 26 shown in FIG.
Similarly to the detection circuit 21, when the characteristic impedance of the frequency conversion line 27 is different between the positive side and the negative side of the microwave electric field, the voltage of the difference frequency of the two microwaves applied to the frequency conversion line 27 is applied to the frequency conversion line 27. The conductor pattern is formed on the ferroelectric base material region A so as to perform frequency conversion utilizing the occurrence. The bias voltage is 1 /
The power is supplied through a microwave choke line 29 formed by a combination of four wavelength transmission lines. The choke line 28 is formed in the paraelectric region B so that the choke effect is not deteriorated by the control voltage. The frequency conversion line 27 and the input lines a and b are formed so that the bias voltage does not affect the input lines. They are connected via a capacitor 29.

On the frequency conversion line 27, microwaves of two frequencies whose electric field strength is large enough to change the dielectric constant of the line board material are propagated. A bias voltage having an electric field strength sufficient to shift the dielectric constant of the plate material to one side is applied. Then, the characteristic impedance of the frequency conversion line 27 with respect to the microwave of two frequencies propagating through the line differs between the positive side and the negative side of the microwave electric field, and similarly to the diode frequency conversion circuit, when viewed from the frequency conversion load. Since the signal source impedance is different between the positive side and the negative side of the microwave, frequency conversion of the microwave becomes possible.

As described above, according to the ferroelectric transmission line of this embodiment, each microwave circuit can be realized without using a semiconductor diode.

[0024]

As described above, the ferroelectric transmission line according to the present invention does not use a semiconductor diode but is composed of only a dielectric material including a ferroelectric and a conductor pattern, and has a non-linear dielectric constant of the ferroelectric. It actively utilizes characteristics. For this reason, while having the function to replace the microwave circuit using the conventional semiconductor diode, a low-cost, voltage-controlled filter circuit, voltage-controlled resonance circuit, voltage-controlled resonance circuit, modulation circuit, detection circuit, frequency conversion circuit, etc., which is free from the influence of the parasitic reactance component, etc. Can be configured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a ferroelectric transmission line according to the present invention and an explanatory diagram showing a nonlinear dielectric constant.

FIG. 2 is a plan view showing an embodiment of various microwave circuits constituted by the ferroelectric transmission line of the present invention.

FIG. 3 is an explanatory diagram of a conventional microwave transmission line.

FIG. 4 is a configuration diagram of a conventional microwave circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ferroelectric substrate material 2, 41 Paraelectric substrate material 3, 42 Conductor pattern 4, 43 Ground conductor 11, 44 Voltage control filter circuit 14 Voltage control resonance circuit 17 Modulation circuit 21 Detection circuit 26 Frequency conversion circuit 45 Varactor diode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 3/08 H01P 1/00 H01P 1/203 H01P 7/08 H03D 3/16

Claims (6)

(57) [Claims] A ferroelectric material whose permittivity varies according to the magnitude of an applied electric field is provided on a ground conductor, and a transmission line for transmitting microwaves on the ferroelectric material is formed by a conductor pattern; A ferroelectric transmission line, wherein a characteristic of the microwave is changed by changing a dielectric constant of the ferroelectric material according to a voltage applied to a pattern. 2. A change in the dielectric constant of a ferroelectric material so that the center frequency of a microwave that is coupled to each of an input line and an output line by an electric field and propagates on a transmission line can be controlled by an applied voltage. 2. The ferroelectric transmission line according to claim 1, wherein a filter circuit for changing a wavelength shortening rate of the microwave is formed by a conductor pattern. 3. The method according to claim 1, wherein the frequency of the microwaves coupled to the input / output shared line by an electric field and resonating on the transmission line can be controlled by the applied voltage. 2. The ferroelectric transmission line according to claim 1, wherein a resonance circuit for changing the wavelength shortening rate of the microwave is formed by a conductor pattern. 4. The power of a microwave coupled to an input line and an output line by an electric field and propagating on a transmission line,
2. The ferroelectric circuit according to claim 1, wherein a modulation circuit for changing a characteristic impedance of the transmission line in accordance with a change in a dielectric constant of the ferroelectric material is formed by a conductor pattern so as to be controllable by an applied voltage. Body transmission line. 5. The method according to claim 1, wherein the ferroelectric material has a dielectric constant, which is coupled to the input line by an electric field and generates a voltage signal corresponding to the power of the microwave propagating on the transmission line. 2. The ferroelectric transmission line according to claim 1, wherein a detection circuit for differentiating between the positive side and the negative side of the voltage is formed by a conductor pattern. 6. A ferroelectric material, which is coupled to two input lines by an electric field and generates a signal having a frequency corresponding to a difference between two input microwaves, according to an applied voltage.
2. The ferroelectric transmission line according to claim 1, wherein a frequency conversion circuit for making the positive and negative sides of the two microwave voltages different from each other is formed by a conductor pattern.