JPH02283101A - Variable resonance circuit - Google Patents

Abstract

PURPOSE:To make the size of circuit small and to improve the characteristic by forming a center conductor of a coaxial mode resonator to be hollow, inserting a variable reactance element in the inside of the hollow part so as to connect it with a resonator in parallel or series in terms of high frequency. CONSTITUTION:The length of a coaxial mode resonator 11 is l and the resonator 11 consists of a hollow center conductor 12 and an outer conductor 13 and a dielectric material 14, and a variable reactance element (variable capacitive element) 16 is contained in the inside of the hollow part of the conductor 12 and one tip 15 of the conductors 12, 13 is terminated with a short-circuit. Then the variable resonance circuit is formed between an external connection terminal 22 and the outer conductor 13 of the resonator 11 and the resonator 11 and the element 16 are connected in parallel in terms of high frequency. Thus, from the definition of a coaxial mode resonator whose termination is short-circuited, the resonator acts like a series resonance circuit at a frequency in which the length l is 1/2 waveform length and acts like a parallel resonance circuit at a frequency in which the length l is 1/4 waveform length. That is, the element 16 is contained in the inside of the conductor 12 to save the circuit space, the resonator 11 and the conductor 16 are connected in a short distance to make the size of the circuit small and to obtain an excellent performance.

Description

[Detailed description of the invention] Main presentation and public corporation The present invention relates to a variable resonant circuit and a voltage controlled oscillator.

It can be applied to all devices that require a variable resonant circuit, such as variable filters.

In recent years, as demand in the communications field has expanded, information processing equipment has been required to be smaller and more sophisticated. In particular, reducing the size of key components such as voltage-controlled oscillators and variable filters has made it a big issue to save space in variable resonant circuits.

FIGS. 6(a) and 6(b) are external views of a coaxial mode resonator 1 and a variable reactance element 2 used in a general variable resonance circuit. To configure the variable resonant circuit, the two elements 1 and 2 described above are connected in parallel or in series.

FIG. 7 shows an example of a conventional parallel variable resonant circuit constructed using the above elements 1 and 2. In Figure 7, (a) is a perspective view, (
b) is a top view. Conventionally, in order to configure a variable resonant circuit as shown in the figure, a connecting line pattern 4 and a grounding pattern 5 are provided on a dielectric substrate 3, the two elements are arranged and mounted on a plane, and connected in parallel at high frequency. is taken. Also, in the case of a series variable resonant circuit, it is similarly arranged in a plane and the above 2.
It is constructed by connecting elements in series at high frequency.

A section that tries to eat away at Japan's power.

By the way, in the conventional variable resonant circuit configuration, since the resonator 1 and the variable reactance element 2 are arranged in a plane, the space occupied by the circuit needs to be at least as much as the space for the two elements. Further, as shown in FIG. 7, a connection line pattern 4.5 is used to connect the resonator 1 and the variable reactance element 2, but in the microwave region of several Gllz or more, the impedance of the line pattern becomes high frequency δ. This leads to a problem in that it is connected in series to the variable reactance element 2, resulting in deterioration in performance such as fluctuations in the resonant frequency and a decrease in the Q of the resonant circuit.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a variable resonant circuit that is small in size and has good characteristics.

Means for Solving Problem q 4 In the variable resonant circuit according to the present invention, in order to solve the above problem, the center conductor of the coaxial mode resonator is formed hollow,
A variable reactance element is inserted into the hollow part, and both are connected in parallel or in series at high frequency.

According to the present invention, the circuit space is approximately the space for one element of the coaxial mode resonator, and the two elements are connected in parallel or in series at high frequency with the shortest distance.
It is possible to construct a variable resonant circuit that is small and has extremely good characteristics, with almost no deterioration in performance such as fluctuations in resonant frequency or reduction in Q of the circuit that have been observed in the past.

Hereinafter, the variable resonant circuit according to the present invention will be explained according to the drawings. 1 to 4 show the first to fourth embodiments, respectively, and each embodiment will be explained using a variable capacitance element, which is the most typical variable reactance element, as an example. .

FIG. 5 shows computer simulation results before and after implementation in the first example.

The embodiment described here can be applied to any circuit in which a variable resonant circuit is used, such as a voltage controlled oscillator or a variable filter. The basic configuration is to connect them in parallel or series over the shortest distance at high frequency. Each example will be described in more detail below.

FIG. 1 shows a first embodiment of the present invention. The figure (a) is a perspective view, (b) is a rear perspective view, and (C) is an AA
FIG. The coaxial mode resonator II has a length β
It consists of a hollow center conductor 12, an outer conductor 13 that surrounds the outer periphery of the center conductor 12 with a gap in between, and a dielectric 14 that fills the gap between both door bodies. is short-terminated.

In this embodiment, a variable capacitance element 16 is housed inside the hollow portion of the center conductor 12 of the resonator. The cathode terminal 17 of the variable capacitance element 16 is connected to the connection electrode 18.
The anode terminal 20 is connected to the input side end point 19 of the hollow center conductor of the coaxial mode resonator 11 via the connecting electrode 21, and the anode terminal 20 is connected to the short-circuit termination surface 15 of the coaxial mode resonator 11 via the connecting electrode 21. Furthermore, connect the external connection terminal 22 to the above input end point 1.
9 and used as a connection terminal between this resonant circuit and an external circuit. Note that the external connection terminal 22 is connected to the variable capacitance element 1.
It may also be used as the cathode terminal 17 of No. 6.

In this embodiment, a variable resonance circuit is formed between the external connection terminal 22 and the outer conductor 13 of the resonator 11, and the coaxial mode resonator 11 and the variable capacitance element 16 are connected in parallel at high frequency. There is.

From the definition of a coaxial mode resonator with shorted terminals, the above resonator becomes a series resonant circuit at a frequency where the length l becomes a half wavelength, and a parallel resonant circuit at a frequency where 2 becomes a quarter wavelength. Therefore, the equivalent circuit of the above variable resonant circuit is shown in Figure 1 (d
), two types of forms can be constructed.

Regardless of which equivalent resonant resonant circuit is configured, in this example the circuit space is reduced by almost half by housing the variable reactance element inside the hollow center conductor of the coaxial mode resonator, and the circuit space is reduced by almost half. Since the connection can be realized over the shortest distance, deterioration of characteristics can be suppressed as much as possible.

FIG. 5 is a comparison diagram of computer simulation results of the real part of impedance between the variable resonant circuit according to the above embodiment and the conventional variable resonant circuit shown in FIG.

In the figure, the resonant frequency of the coaxial mode resonator is 2.678
GHz, the value of the variable capacitance element is 0.19F, and the 50Ω line length for connecting the variable capacitance element is 3 mn+. The Q of the circuit is determined by the sharpness of the curve shown in FIG. The result was approximately 325, an improvement in Q of approximately 22%.

FIG. 2 shows a second embodiment of the present invention, in which a variable capacitance element 16 is housed in a hollow portion of a hollow center conductor 12 of a coaxial mode resonator 11 whose tip is short-terminated as in the first embodiment. In this embodiment, contrary to the first embodiment, the anode terminal 20 of the variable capacitance element is connected to the coaxial mode resonator 1 via the connection electrode 18.
1, and the cathode terminal 17 is drawn out from the short-circuit termination surface side of the coaxial mode resonator 11 and connected to the external circuit connection terminal 22. The control voltage of the variable capacitance element 16 is applied between the cathode terminal 17 and the anode terminal 20 with high frequency insulation. In addition, external connection terminal 22
may also be used as the cathode terminal 17 of the variable capacitance element.

In this embodiment, as in the first embodiment, a variable resonant circuit is formed between the external connection terminal 22 and the outer conductor 13 of the resonator 11, but in this embodiment, the coaxial mode resonator 11 and the variable capacitance Elements 16 are connected in series at high frequency. Furthermore, from the definition of a coaxial mode resonator with shorted terminals,
The above resonator has a frequency where l is a half wavelength and 2 is 4
Since the form of the resonant circuit differs depending on the frequency that corresponds to one-wavelength, the equivalent circuit of the variable resonant circuit can be configured into two types as shown in FIG. 2 (dl).

In this embodiment as well, the variable reactance element is housed inside the hollow center conductor of the coaxial mode resonator, making it possible to save space in the circuit, and furthermore, since the two elements described above are connected over the shortest distance, there is no possibility of deterioration of characteristics. It can be suppressed as much as possible.

FIG. 3 shows a third embodiment of the invention. The coaxial mode resonator 11 has a length l, and the front end of the resonator is open-ended. In this embodiment as well, the variable capacitance element 16 is housed inside the hollow center conductor 12 of the resonator, and the cathode terminal 17 of the variable capacitance element is connected to the coaxial mode resonance via the connection electrode 18. The anode terminal 20 is connected to the connecting electrode 2 at the input end point 19 of the hollow center conductor of the device.
3 to the outer conductor 13 of the coaxial mode resonator. Furthermore, connect the external connection terminal 22 to the above input side end point 1.
9 and used as a connection terminal with an external circuit. Note that the external connection terminal 22 is the cathode terminal 17 of the variable capacitance element 16.
May also be used with.

In this embodiment, a variable resonance circuit is formed between the external connection terminal 22 and the outer conductor 13 of the resonator 11, and the coaxial mode resonator 11 and the variable capacitance element 16 are connected in parallel at high frequency. There is. Here, P: From the definition of an open-ended coaxial mode resonator, the resonator 11 is! At the frequency where is 1/2 wavelength, it becomes a parallel resonant circuit,! is one quarter
Since the variable resonance circuit becomes a series resonant circuit at a frequency corresponding to a wavelength of

In this embodiment as well, by housing the variable reactance element inside the hollow center conductor of the coaxial mode resonator and connecting the two elements at the shortest distance, deterioration of characteristics can be suppressed and space can be saved.

FIG. 4 shows a fourth embodiment of the present invention, in which a variable capacitance element 16 is housed in the hollow part of a hollow center conductor 12 of a single coaxial mode resonator whose tip is open-terminated as in the third embodiment. However, in this embodiment, contrary to the third embodiment, the anode terminal 20 of the variable capacitance element 16 is connected to the input side end point 19 of the coaxial mode resonator 11 via the connection electrode 18, and the cathode terminal 17 is connected to the input end point 19 of the coaxial mode resonator 11. It is pulled out from the open end surface side of the coaxial mode resonator 11 and connected to the external connection terminal 22. The control voltage of the variable capacitance element is high-frequency insulated and connected to the cathode terminal 1.
7 and the anode terminal 20. Note that the external connection terminal 22 may also be used as the cathode terminal 17 of the variable capacitance element.

In this embodiment, as in the third embodiment, a variable resonant circuit is formed between the external connection terminal 22 and the outer conductor 13 of the resonator 11, but in this embodiment, the coaxial mode resonator 11 and the variable capacitance Elements 16 are connected in series at high frequency. Furthermore, according to the definition of an open-ended coaxial mode resonator, the above resonator has a frequency whose length is one-half the wavelength, and two
Since the form of the resonant circuit differs depending on the frequency at which the variable resonant circuit becomes a quarter wavelength, two types of equivalent circuits of the variable resonant circuit can be constructed as shown in FIG. 4(d).

In this embodiment, as in the third embodiment, it is possible to construct a variable resonant circuit that saves circuit space and minimizes deterioration of characteristics.

As explained above, in the present invention, a variable reactance element is inserted into the hollow part of the center conductor of a coaxial mode resonator having a hollow center conductor, and the variable reactance element is connected in series or in parallel at the shortest distance in terms of high frequency. It is possible to configure a variable resonant circuit that minimizes the decrease in the sharpness Q of the resonance curve, and the circuit space is only required for the coaxial mode resonator, making the variable resonant circuit more compact and high performance. It is possible,
It has greatly contributed to the miniaturization of electronic devices.

[Brief explanation of drawings]

1, 2, 3, and 4 are diagrams showing first to fourth actual phase examples of the variable resonant circuit according to the present invention, and (a) and (b) are perspective views. Figure, (C) is a cross-sectional view, (
d) is an equivalent circuit. FIG. 5 is a perspective view and a plan view of the variable resonant circuit. I L - Coaxial mode resonator 12 - Center conductor 13 of coaxial mode resonator - Outer conductor 114 of coaxial mode resonator - Dielectric 16 -
Variable reactance element 17 Cathode terminal 18 of variable reactance element
Connection terminal 2〇 - Anode terminal of variable reactance element 21 - Connection terminal.

Claims (1)

[Claims] (1) A coaxial mode resonator consisting of a hollow center conductor, an outer conductor covering the outer periphery of the center conductor, and a dielectric material filled in the gap between the center conductor and the outer conductor, and a hollow center conductor of the coaxial mode resonator. 1. A variable resonant circuit comprising: a variable reactance element installed inside the section and connected to the coaxial mode resonator in a high frequency manner.