CN100517950C - Oscillator coupling system - Google Patents

Abstract

The invention relates to an oscillator coupling system, which comprises a plurality of oscillation elements and a plurality of delay elements, wherein the delay elements are connected between at least two oscillation elements, a specific phase or time delay relation exists between the delay elements, the delay elements are coupled with the phase or frequency noise suppression correlation characteristics of the at least two oscillation elements, the automatic correlation of noise is reduced in the operation of a circuit system, the suppression effect of phase or frequency noise is improved, and a solid circulator or an isolator or a resonant cavity occupying space is avoided, so that the signal distortion is reduced and the system stability is improved.

Description

An oscillator coupling system

technical field

The present invention relates to a noise reduction technology, in particular to an oscillator coupling system applied to provide phase or frequency noise suppression in high frequency/low frequency environments.

Background technique

In communication circuits and electronic systems, noises generated by signal sources or oscillation generating components will limit the overall efficiency of the system. Among them, there are many reasons for noise interference, such as lightning strikes, switching of peripheral load equipment, generators, Radio communication, poor wire contact, poor switch engagement, improper grounding and radio wave interference, etc. If the phenomenon of noise generation is not eliminated, it will easily lead to random errors in data file access or executable files on storage devices, and it will easily cause abnormal operations of calculators and controllers or interfere with communication systems on electronic products.

In order to reduce the impact of noise, many companies have developed phase or frequency noise reduction technologies, including low-frequency oscillation noise suppression for semiconductor devices, special oscillator circuit design, and resonator design with high quality factor (Q-factor). , and the injection signal (injection signal) as a phase locked (phase locked) to achieve the reduction of phase or frequency noise and other technologies, wherein the injection signal reduction of phase or frequency noise technology can be divided into high-frequency signal injection, low-frequency signal injection and high-frequency signal injection Frequency oscillator signal low frequency oscillator signal mixed signal injection, but in view of the advancement of technology, more and more systems are used in high frequency in the field of electronics and communication.

Please refer to FIG. 1a, which is a schematic block diagram of an existing oscillator coupling system. As shown in the figure, a delay element 21' is connected in series between the first oscillating element 11' and the second oscillating element 13'. The frequency and noise generated by the first oscillating element 11' are input to the output end of the second oscillating element 13' through the delay element 21', and the frequency and noise generated by the second oscillating element 13' are input through the delay element 21' To the output terminal of the first oscillating element 11', so that the output signals of different oscillators achieve the same operating frequency, and cause phase locked (phase locked), and generate a certain phase or frequency between the circuit systems through the noise input of different oscillators The correlation of the degree of noise suppression, and the oscillating signal after the phase or frequency noise reduction is used for the circuit load, and a more stable working environment can be obtained. Therefore, existing oscillator coupling systems have been used in applications such as high power combining (Power Combining) systems and active phased arrays (Active Phased Array).

Please refer to Figure 1b, using the phase-shifted and mutually injected oscillating signals as phase locked to suppress the generation of noise, where the oscillator coupling method and required components are roughly the same as the above, but the main difference lies in the first After the output of the two oscillating elements 13', the phase of the oscillating signal and the noise is shifted by a set angle through a phase shifting element 15', and then the noise between the two oscillating elements is suppressed, and the signal of a mode frequency in the oscillator can be suppressed, while boosting the signal at another mode frequency. In this way, the power combination of specific frequency signals in the oscillator can be improved. The entire coupling circuit is called a push-push oscillator. Compared with any single oscillator, the coupling circuit has 6dB of signal power. improve.

In addition, in the prior art shown in Figure 1c, a delay element 21' composed of two unidirectional amplifiers in opposite directions is arranged between two oscillating element circuits to realize the noise suppression of the two oscillating elements. characteristics, such as known cross-coupled oscillators and quadrant-coupled oscillators, it should be noted that the delay element 21 ′ cannot destroy the oscillation characteristics of the oscillator itself.

In the above existing oscillator coupling system, a coupling circuit is connected between two oscillators, and the coupling circuit can transmit the oscillation signal in the oscillator. If the circuit connecting two oscillators only provides a fixed direct current (DC) voltage or direct current (DC) current or ground (Ground) that does not change with time, it cannot be regarded as a coupled circuit. Without the coupling circuit, the oscillation of the two oscillators Signals are not correlated. Therefore, through the noise characteristics of the two oscillators, the coupling circuit produces a coupling property in which different noise amplitudes cancel each other out between the noises of the two oscillators, so as to achieve a certain degree of noise suppression and stabilize the Under the condition of the output signal frequency, the best phase noise can be reduced by 10log2=3dB, but in the environment of N oscillators in-phase coupling system (N is a positive integer), the best phase noise can only be reduced by 10logN dB (phase noise ).

However, due to the advancement of science and technology, the frequency of satellite communication, satellite network, satellite positioning, and wireless network is getting higher and higher, which has reached tens of MHz to tens of GHz. The aforementioned technology of coupling at least two oscillators If the influence of noise cannot be reduced more effectively, the signal-to-noise ratio of the entire communication system will be limited, which will affect the minimum detectable signal power of the system, so that the effective transmission and reception distance of the signal is limited, and there is a bandwidth Insufficient problems arise.

Therefore, how to effectively solve the problems existing in the above technologies, and develop a system that can meet the requirements of high-frequency circuits and have better phase or frequency noise suppression effects, so as to increase the system operating bandwidth, improve operating efficiency and avoid phase or frequency noise Affecting the output effect is an urgent problem to be solved in related fields.

Contents of the invention

The technical problem to be solved by the present invention is to provide an oscillator coupling system that simplifies the difficulty of noise suppression with simple circuit components.

Another object of the present invention is to provide an oscillator coupling system to improve the suppression effect of phase or frequency noise, reduce distortion, and increase system stability.

Another object to be solved by the present invention is to provide an oscillator coupling system, which can increase the bandwidth in high-frequency applications, reduce phase or frequency noise interference, change input and output impedances, and achieve energy-saving effects.

In order to achieve the above object, the present invention provides an oscillator coupling system, comprising a plurality of oscillating elements; at least one first delay element, connected between at least two oscillating elements, as signals injected into the oscillator mutually, to achieve phase locking ( phase locked); and at least one second delay element, which is connected between at least two oscillating elements and introduces a phase or time delay parameter at least several times higher than that of the first delay element, so that the coupling has phase or frequency noise suppression Correlating characteristics of at least two oscillating components, and reducing the autocorrelation of the oscillator's noise, so as to achieve the effect of enhancing noise suppression during system operation.

The first delay element is selected from one of an adjustable resistance-capacitance-inductance compound circuit element and a bidirectional amplifier (that is, two reverse unidirectional amplifiers), and is used to inject oscillation signals of at least two oscillating elements into each other to achieve phase locking (phase locked), and the optimal phase delay can reach an integer multiple of π, wherein, in the adjustable operating frequency range, the optimal value of the delay is related to the equivalent circuit model of at least two oscillators, and in order to make at least There is a better noise suppression effect between the two oscillators, so that the phase or time delay value of the second delay element (that is, the phase or time delay difference between the second and the first delay element) is at least set to that of the first delay element several times more.

Furthermore, the second delay element can provide an additional degree of design freedom, and a resistor can be connected in series to adjust the quality factor of the second delay element and the strength of the injected signal. In addition, the second delay element is selected from At least one of the adjustable resistance-capacitance-inductance composite circuit element, delay signal line, delay IC, unidirectional amplifier, and bidirectional amplifier, to coordinate with the system circuit to adjust the time delay parameter of the second delay element and its equivalent phase delay parameter; The second delay element is used for the time delay or phase delay of the oscillator injection signal, so as to reduce the autocorrelation (autocorrelation) of the noise of the oscillating element, so as to achieve better coupling phase or frequency noise suppression correlation characteristics, so that the oscillator The coupling system can be calibrated or optimized to match the circuit characteristics of different products.

The oscillator coupling system proposed by the present invention utilizes a coupling configuration of at least one first delay element and at least one second delay element between at least two oscillating elements to reduce the noise autocorrelation (autocorrelation) of the oscillator and achieve better Excellent phase or frequency noise suppression effect, and then through the series connection of the resistor and the second delay element, to adjust the quality factor of the second delay element and the strength of the injected signal, and adjust the time delay of the second delay element in conjunction with the system circuit parameter and its equivalent phase delay parameter. The oscillator coupling system uses simple circuit components, avoids the use of solid-state (SolidState) circulator (Circulator) or isolator (Isolator) or resonator (Resonator), and at the same time simplifies the difficulty of noise suppression, thereby improving noise suppression effect, reduce signal distortion, and increase system stability. At the same time, it can be generally used in the system working environment of high-frequency and low-frequency related application products, and has the effect of increasing bandwidth, reducing noise interference, and changing input and output impedance to achieve energy saving. The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Figure 1a is a schematic block diagram of an existing oscillator coupling system;

Fig. 1b is a schematic block diagram of an existing high-frequency oscillator coupling system;

Figure 1c is a schematic block diagram of an existing system coupled to an oscillator;

Fig. 2 is the schematic block diagram of the oscillator coupling system of the present invention;

Fig. 3 is the schematic block diagram of oscillator unidirectional amplification coupling system of the present invention;

Fig. 4 is the schematic block diagram of the two-way amplification coupling system of the oscillator of the present invention;

5 is a schematic block diagram of an oscillator coupling system applied to a high-frequency environment according to the present invention;

6 is a schematic block diagram of the present invention coupled to the internal system of the oscillator;

7 is a schematic block diagram of an oscillator system that uses a mixer to mix the output and non-output ends of the present invention and modulates the two-way coupling through a filter and an amplifier;

8 is a schematic block diagram of an oscillator system that uses a mixer to mix the output and non-output ends of the present invention and modulates the unidirectional coupling through a filter and an amplifier;

9 is a schematic block diagram of a delay element connected in series with a resistor in the oscillator coupling system of the present invention;

10 is a schematic diagram of the oscillator coupling system of the present invention adjusting the strength of the injected signal to change the influence of the quality factor and phase delay parameters on the system; and

FIG. 11 is a schematic diagram comparing the phase or frequency noise suppression effect of the oscillator coupling system of the present invention with that of the prior art.

11, 11'- the first oscillating element 13, 13'- the second oscillating element

15, 15'-phase shift element 21-first delay element

21'-delay element

23, 23', 25', 27', 29' - second delay element

231, 233-unidirectional amplifier 235-mixer

237-Filter 239-Resistor

31, 33, 31’, 33’-load

Detailed ways

The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification

Please refer to FIG. 2, which is a schematic block diagram of the oscillator coupling system of the present invention. As shown in the figure, the oscillator coupling system of the present invention includes a plurality of oscillating elements 11 and 13; it is connected between at least two oscillating elements 11 and 13 and a second delay element 23 connected between the at least two oscillating elements 11 and 13 and in parallel with the first delay element 21, through which the second delay element 23 introduces The phase or time delay parameter of the first delay element 21 at least several times or more (that is, the phase or time delay difference between the second and the first delay element is more than several times the phase or time delay value of the first delay element 21) and Coupling a plurality of oscillating elements 11 and 13 with phase or frequency noise suppression correlation characteristics, and reducing the autocorrelation (autocorrelation) of the oscillator noise, so as to achieve the effect of improving noise suppression in system operation, and then reduce at least several dB to tens of dB of noise.

The first delay element 21 connects the output end of the first oscillating element 11 to the output end of the second oscillating element 13, and the second delay element 23 is connected in parallel with the first delay element 21 and is arranged on the first oscillating element. Between the output terminal of 11 and the output terminal of the second oscillating element 13, it is used to increase the time or phase delay of the mutually injected signals of at least two oscillators, to suppress the autocorrelation of noise (autocorrelation), to reduce the noise of the oscillator , that is, the first delay element 21 and the second delay element 23 are connected in series to at least two oscillation elements (that is, the first oscillation element 11 and the second oscillation element 13) having phase or frequency noise suppression related characteristics , to enhance its phase or frequency noise suppression correlation characteristics and effects, to obtain better noise suppression output benefits, and have better electrical effects on the load 31 and the load 33, and the first delay element 21 and The second delay element 23 can be a bidirectional signal line.

Please refer to Fig. 3, which is a schematic block diagram of the oscillator unidirectional amplification and coupling system of the present invention, as shown in the figure, its system composition and use technology are roughly the same as those of the above-mentioned embodiment, but the main difference is that the second delay element is A unidirectional amplifier 231 is used to amplify the output oscillating signal of the second oscillating element 13 and increase the phase or time delay, and couple to the output end of the first oscillating element 11, so that the first oscillating element 11 has enhanced The phase or frequency noise suppression associated with the second oscillating element 13 is used to reduce the autocorrelation of noise, and the second oscillating element 13 only maintains phase or frequency with the first oscillating element 11 by the first delay element 21 Frequency noise suppression correlation characteristics are used to enable the first oscillating element 11 to output a better phase or frequency noise suppression signal to the load 31 to reduce manufacturing costs and obtain better phase or frequency noise suppression effects.

Please refer to Fig. 4, which is a schematic block diagram of an oscillator bidirectional amplifying coupling system of the present invention, as shown in the figure, its system composition and use technology are all roughly the same as those of the above-mentioned embodiment, the main difference is that the unidirectional amplifier 231 makes the The first oscillating element 11 has the characteristic of enhancing the noise suppression correlation with the second oscillating element 13 to reduce the automatic correlation (autocorrelation) of the noise, and a unidirectional amplifier 233 is added to couple the output signal of the first oscillating element 11 To the output end of the second oscillating element 13, that is, in parallel with the unidirectional amplifier 231, so that the second oscillating element 13 has an automatic correlation that enhances the noise suppression correlation characteristics with the first oscillating element 11 to reduce noise (autocorrelation). That is, between the first oscillating element 11 and the second oscillating element 13, the noise suppression correlation between the first oscillating element 11 and the second oscillating element 13 can be enhanced through the unidirectional amplifier 231 and the unidirectional amplifier 233 characteristics to obtain better noise-suppressed output benefits, have better electrical effect on load 31 and load 33, and can reduce the possibility of signal distortion, but the signal of unidirectional amplifier 231 and unidirectional amplifier 233 Gain, time and phase delay must avoid possible formation of positive feedback loop oscillation (positive feedback loop oscillation), which destroys the desired signal frequency and stability of the entire coupling system.

Please refer to Fig. 5, which is a schematic block diagram of an oscillator coupling system applied in a high-frequency environment according to the present invention. As shown in the figure, its system composition and use technology are roughly the same as those of the embodiment in Fig. 2, the main difference lies in the second oscillating element The output end of 13 is provided with a phase shift element 15, suppresses the generation of noise by adding the mode of this phase shift element 15, can reduce the noise of reaching 3dB in the best case, suppresses the signal of a mode in the oscillator simultaneously, and improves The signal of another mode frequency can increase the power combination of the specific frequency signal in the oscillator, and then the time or phase delay provided by the second delay element can further reduce the noise of several dB to tens of dB, so as to Reduce the noise autocorrelation of the oscillating element, increase the bandwidth and signal stability of the circuit system, and reduce the input and output impedance in the circuit system to save output power and achieve energy saving. Therefore, the oscillator coupling system can meet the requirements of high-frequency application products (such as satellite communication systems, wireless network link systems, mobile phone communication systems, etc.) to provide better noise suppression effects.

Please refer to FIG. 6, which is a schematic block diagram of the present invention coupled to the internal system of the oscillator. As shown in the figure, its system configuration and use technology are roughly the same as those of the embodiment in FIG. 2, and the main difference is that the second delay element 23 can be coupled to Anywhere between the first oscillating element 11 and the second oscillating element 13, different high and low frequency signals in the oscillator can be injected into each other, and the time or phase delay of the second delay element 23 can reduce the noise auto-correlation of each oscillator (autocorrelation), for the convenience of meeting different circuit design requirements. The second delay element 23 can be selected from at least one of an adjustable resistor-capacitor-inductance compound circuit element, a delay signal line, a delay chip (delay IC), a one-way amplifier, and a two-way amplifier, wherein the low-frequency signal can be generated by a non-conductor of the oscillator itself. The linear characteristic or element is formed by mixing its own signal and the signal of the coupled oscillator through the first delay element 21 .

Please refer to Fig. 7, which is a schematic block diagram of an oscillator system that uses a mixer to mix the output and non-output terminals of the present invention and then modulates the bidirectional coupling through a filter and an amplifier. As shown in the figure, its system composition and use technology are similar to those of The embodiment in FIG. 2 is roughly the same, and the main difference is that the second delay element 23 is composed of a composite circuit, including a plurality of delay elements 23' and 25' respectively arranged at the output ends of the first oscillating element 11 and the second oscillating element 13. , and the output oscillating signals of the two oscillating elements are mixed with the mixer 235, and the signals are amplified by the filter 237 and the one-way amplifier 231 and output to a plurality of delay elements 27' and 29', in order to mix and adjust The transformed output signal is respectively coupled to the non-output end of the first oscillating element 11 and the non-output end of the second oscillating element 13, so that the two oscillating elements have enhanced noise suppression correlation characteristics when forming oscillations, so as to reduce noise Autocorrelation. In short, at least one second delay element 23 of the oscillator coupling system of the present invention mixes and modulates the time delay factor or phase delay factor through the signals at the output ends of the two oscillator elements, and outputs either a low frequency signal or a high frequency signal, Simultaneously injected into the non-output ends of the two oscillating elements to achieve better output benefits of phase or frequency noise suppression, and to meet the requirements of different high and low operating frequencies to suppress phase or frequency noise. For the load 31 and the load 33, then It has a better electrical effect and reduces the possibility of signal distortion.

Please refer to Fig. 8, which is a schematic block diagram of an oscillator system that uses a mixer to mix the output and non-output ends of the present invention and then modulates the unidirectional coupling through a filter and an amplifier. As shown in the figure, its system composition and use technology are both It is roughly the same as the embodiment shown in FIG. 7 , the main difference is that the second delay element 23 is composed of a composite circuit, including a plurality of delay elements 23' and 25' respectively arranged on the sides of the first oscillating element 11 and the second oscillating element 13. output terminal, and the output oscillation signals of the two oscillating elements are mixed with the mixer 235, and the signal is amplified by the filter 237 and the one-way amplifier 231 and output to the delay element 27' for mixing and modulating The final output signal is coupled to the non-output end of the second oscillating element 13, so that the two oscillating elements have enhanced noise suppression correlation characteristics when forming oscillations, so as to reduce the autocorrelation of noise. In short, at least one second delay element 23 of the oscillator coupling system of the present invention mixes and modulates the time delay factor or phase delay factor through the signals at the output ends of the two oscillator elements, and outputs either a low frequency signal or a high frequency signal, Inject into the non-output end of the second oscillating element 13 to achieve the relative noise suppression correlation characteristics with the first oscillating element 11, and achieve the output benefit corresponding to the phase or frequency noise suppression of the first oscillating element 11, and cooperate with different levels The requirement of the operating frequency to suppress phase or frequency noise has a better electrical effect on the load 31 and the load 33 and reduces the possibility of signal distortion.

Please refer to Fig. 9, which is a schematic block diagram of the delay element and the resistor connected in series in the oscillator coupling system of the present invention. The resistor 239 is connected in series with the second delay element 23 to adjust the quality factor of the second delay element 23 and the strength of the injected signal in conjunction with the system circuit, wherein the second delay element 23 can also be selected from an adjustable resistor-capacitor-inductance composite At least one of circuit elements, delay signal lines, delay ICs, unidirectional amplifiers, and bidirectional amplifiers is used to adjust the time delay parameter and its equivalent phase delay parameter of the second delay element 23 in coordination with the system circuit to achieve better coupling Phase or frequency noise suppression correlation feature.

Please refer to FIG. 10 , which is a schematic diagram of adjusting the strength of the injected signal to change the influence of the quality factor and the delay phase factor on the system for the oscillator coupling system of the present invention. As shown in the figure, the delay time is proportional to the delay phase, so adjusting the delay phase is equivalent to To adjust the delay time, please refer to FIG. 9. In the oscillator coupling system of the present invention, the resistance 239 is used to connect the second delay element 23 in series to adjust the quality factor of the second delay element 23 and the strength of the injected signal. Weak (ρ), and adjust the phase delay parameter (Δθ) of the second delay element 23 to provide the noise suppression effect required for circuit system circuit adjustment, wherein the smaller the series resistance value, the higher the quality factor, and the noise The better the suppression effect, the longer the delay phase or time, the better the phase or frequency noise suppression effect.

Please refer to Fig. 11, which is a schematic diagram of the comparison between the phase or frequency noise suppression effect of the oscillator coupling system of the present invention and the prior art, as shown in the figure, the effect of the prior art suppression phase or frequency noise is shown in spectrum 1, at the oscillation frequency Under the condition of fixed signal power, due to the heavy noise interference, the noise level of the spectrum signal on both sides of the oscillation frequency is relatively high; under the condition of fixed signal power of the same oscillation frequency, because the spectrum 2 is added with the noise suppression effect of the phase shift element, Therefore, noise interference is reduced, resulting in lower noise levels of spectrum signals on both sides of the oscillation frequency; and under the condition of fixed signal power at the same oscillation frequency, spectrum 3 is the phase or frequency noise suppression effect of adding a second delay element, compared with In the spectrum 1 and the spectrum 2, the autocorrelation (autocorrelation) of the oscillator noise is further reduced and has better noise suppression capability, and the noise level of the spectrum signal on both sides of the oscillation frequency is the lowest. Therefore, the oscillator of the present invention The coupling system provides better operating efficiency and lower energy consumption of the circuit system, and at the same time increases the operating bandwidth and system stability of the system.

The oscillator coupling system proposed by the present invention uses at least one first delay element and at least one second delay element coupling configuration between at least two oscillating elements to achieve a better phase or frequency noise suppression effect, and then through the resistance and The series connection of the second delay element is used to adjust the quality factor of the second delay element and the strength of the injected signal, and to adjust the time delay parameter of the second delay element and the like by changing the capacitance value of the second delay element. Effective phase delay parameters. The oscillator coupling system uses simple circuit components to reduce the autocorrelation of oscillation noise and simplify the difficulty of noise suppression, thereby improving the effect of noise suppression, reducing signal distortion, and increasing system stability. It is also suitable for high-frequency applications Under the system working environment of the product, it has the functions of increasing bandwidth, reducing noise interference, and changing input and output impedance to save energy.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes All changes and modifications should belong to the protection scope of the claims of the present invention.

Claims (12)

1, a kind of coupling system of oscillator is characterized in that, comprising:

A plurality of oscillating elements;

At least one first delay element is connected between two oscillating elements at least; And

At least one second delay element, be connected between at least two oscillating elements and introduce compared to first delay element phase place more than the several times or time delay parameter at least, at least two oscillating elements that have phase place or frequency noise inhibition associate feature for coupling, and the automatic correlation of the noise of reduction oscillator, in System Operation, to be reduced to the noise of minority dB to tens of dB.

2, coupling system of oscillator according to claim 1 is characterized in that, this first delay element for be selected from holding wire and amplifier one of them.

3, coupling system of oscillator according to claim 2 is characterized in that, this holding wire for be selected from cable, winding displacement, lead, and electrical transmission line one of them.

4, coupling system of oscillator according to claim 2 is characterized in that, this amplifier be unidirectional amplifier and two-way amplifier wherein at least one.

5, coupling system of oscillator according to claim 1 is characterized in that, this second delay element for be selected from phase delay element and time delay element one of them.

6, coupling system of oscillator according to claim 5 is characterized in that, this phase delay element for be selected from trimmable resistance capacitor and inductor compound circuit element, inhibit signal line, delay chip, and amplifier one of them.

7, coupling system of oscillator according to claim 5 is characterized in that, this time delay element for be selected from holding wire, trimmable resistance capacitor and inductor compound circuit element, inhibit signal line, delay chip and amplifier one of them.

8, coupling system of oscillator according to claim 7 is characterized in that, this holding wire for be selected from cable, winding displacement, lead, and electrical transmission line one of them.

9, coupling system of oscillator according to claim 7 is characterized in that, this amplifier is in unidirectional amplifier and the two-way amplifier at least one.

10, coupling system of oscillator according to claim 1 is characterized in that, this second delay element is serially connected with resistance, in order to the quality factor of adjusting this second delay element and the power of injecting signal to be provided.

11, coupling system of oscillator according to claim 1 is characterized in that, this second delay element is provided with electric capacity, in order to phase place or the time delay parameter of adjusting this second delay element to be provided.

12, coupling system of oscillator according to claim 11 is characterized in that, this electric capacity is modulation electric capacity.

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