CN100488028C - Electronic device with fine-tuning voltage-controlled oscillator - Google Patents

Abstract

A voltage controlled oscillator mounted on a circuit board adjusts phase noise and output frequency range during manufacturing. The voltage-controlled oscillator consists of three parts, including resonant circuit, coupling circuit and oscillating circuit, with the coupling circuit and the resonant circuit having adjustable microstrip capacitors. The two conductive layers of the circuit board are patterned to form overlapped micro-strips, and an insulating layer is sandwiched between the two conductive layers to form the adjustable micro-strip capacitor. The laser is used to cut the adjustable microstrip capacitors in different directions to change the capacitance or make the capacitors show inductance, thereby achieving the purpose of micro-adjusting the output frequency and phase noise of the voltage-controlled oscillator.

Description

Electronic device with trimmable voltage controlled oscillator

technical field

The present invention relates to a voltage controlled oscillator, and more particularly to an electronic device having a voltage controlled oscillator capable of fine-tuning the output frequency range during the manufacturing process.

Background technique

Regardless of whether it is an analog circuit or a digital circuit, oscillators are widely used in today's circuit design to realize various signal processing or communication functions. Voltage Control Oscillator (Voltage Control Oscillator) is an important component used to generate oscillating signals. The working principle of the voltage-controlled oscillator is that it can output different oscillation frequencies by inputting different reference voltages.

Although the development of voltage-controlled oscillators has a long history, with the continuous improvement of the quality requirements of modern electronic equipment for oscillators, the design of voltage-controlled oscillators is also constantly being refurbished. Even so, there are still many problems to be overcome.

One of the common problems is that in the process of manufacturing voltage-controlled oscillators, often due to material limitations or difficulties in process control, the output frequency deviation or phase noise of the voltage-controlled oscillator will deteriorate during the production process. result. However, since the oscillator has been assembled at this time, how to effectively control the manufacturing yield of the voltage-controlled oscillator becomes a big challenge.

Another common problem is that as electronic devices become more and more compact, the design of the entire circuit board is also required to be integrated. Therefore, how to effectively use every space on the circuit board has become a goal to be pursued .

Moreover, there are now more and more high-frequency products, such as wireless phones or wireless networks, etc., with the current surface mount components, because the electrode terminals are parasitic to high-frequency discontinuous stray effects, so for high-frequency The properties of the . Therefore, in the high-frequency field, how to master the material properties to achieve the best product quality is even more important.

Contents of the invention

Therefore, the object of the present invention is to propose an electronic device including a voltage-controlled oscillator with fine-tuning capability, and the voltage-controlled oscillator has the effect of saving the space used by the circuit board, making it more suitable for thin, light and small high-frequency communication product.

The electronic device according to the first embodiment of the present invention includes: a voltage-controlled oscillator having a resonant circuit (resonate circuit), a coupling circuit (coupling circuit) and an oscillating circuit (oscillating circuit); a first patterned conductive layer for The resonant circuit, the coupling circuit and the oscillating circuit are arranged, and the first patterned conductive layer has a plurality of micro-strips (micro-strips) for connecting the resonant circuit, the coupling circuit and the oscillating circuit, and the plurality of The microstrip includes a first upper microstrip formed in the coupling circuit; a second patterned conductive layer having a first lower microstrip overlapping with the first upper microstrip; a first insulating layer set Between the first conductive layer and the second conductive layer, and the insulating layer includes a first through hole, wherein the first through hole is filled with a conductive material, and the first lower microstrip is connected through the through hole to the oscillating circuit, so that the first upper microstrip, the first lower microstrip and the first insulating layer jointly constitute a first adjustable microstrip capacitor in the coupling circuit, wherein the first adjustable microstrip The capacitance of the capacitor can be changed by partially cutting the first upper microstrip, thereby also fine-tuning the VCO to obtain the lowest phase noise.

During the manufacturing process, the capacitance of the tunable microstrip capacitor can be changed by cutting the upper capacitor microstrip, for example, by cutting with a laser. Since one end of the adjustable microstrip capacitor is connected to the resonant circuit and the other end is connected to the oscillating circuit, when its capacitance changes, the coupling between the oscillating circuit and the resonant circuit will change accordingly, which will simultaneously affect the output frequency of the oscillator and phase noise. However, in this embodiment, we only focus on obtaining the lowest phase noise output through the structural design of the voltage-controlled oscillator, and the change of the oscillation frequency will be compensated with the second embodiment.

The electronic device according to the second embodiment of the present invention includes: a voltage controlled oscillator having a resonant circuit, a coupling circuit and an oscillating circuit; a first patterned conductive layer for arranging the resonant circuit, the coupling circuit and the oscillating circuit, and the first patterned conductive layer has a plurality of microstrips for connecting the resonant circuit, the coupling circuit and the oscillating circuit, and the plurality of microstrips include one formed in the resonant circuit The first upper microstrip; a second patterned conductive layer having a first lower microstrip overlapping with the first upper microstrip; an insulating layer placed between the first conductive layer and the second conductive layer , so that the first upper microstrip, the first lower microstrip and the insulating layer jointly constitute a first adjustable microstrip capacitance in the resonant circuit, and the first adjustable microstrip capacitance and an inductance of the resonant circuit connected, wherein, when the first upper microstrip is cut in a first direction, the adjustable microstrip capacitance presents inductance to lower a resonant frequency of the resonant circuit, and when the first upper microstrip is cut in a second direction When the first micro-strip is on, the capacitance value of the adjustable capacitor is reduced to increase the resonant frequency of the resonant circuit, thereby fine-tuning the range of the oscillating frequency generated by the voltage-controlled oscillator.

During the manufacturing process, the capacitance of the adjustable microstrip capacitor can be changed or the capacitance itself can be inductive by cutting the upper microstrip in different directions, such as cutting with a laser. The adjustable microstrip capacitor is arranged in the resonant circuit, and one end is connected with the inductance of the resonant circuit, and the other end is grounded. When the upper microstrip is cut in the first direction, the adjustable microstrip capacitor presents inductance to reduce the resonant frequency of the resonant circuit; and when the upper microstrip is cut in the second direction, the capacitance of the adjustable microstrip capacitor decreases , to increase the resonant frequency of the resonant circuit, thereby fine-tuning the oscillating frequency generated by the voltage-controlled oscillator.

According to the electronic device of the third embodiment of the present invention, it uses the techniques described in the above two embodiments at the same time. That is to say, it uses microstrip capacitors and cutting microstrips in the coupling circuit and resonant circuit at the same time, in order to achieve the lowest phase noise and the most accurate output frequency of the VCO in the mass production process. fine-tuning purpose.

Therefore, the present invention has at least the following advantages.

Firstly, the voltage-controlled oscillator designed according to the present invention can fully utilize the space of the circuit board, thus achieving a more compact design. Secondly, the voltage-controlled oscillator designed according to the present invention can avoid the troubles caused by material or process restrictions on the manufacturing yield of the voltage-controlled oscillator during the manufacturing process, especially when the oscillator is applied at a higher frequency. The advantages of the present invention will be more prominent. Third, the voltage-controlled oscillator designed according to the present invention uses an adjustable microstrip capacitor in the coupling circuit, successfully replacing the traditional surface mount capacitor, which not only provides the ability to fine-tune the phase noise, but also overcomes the traditional surface mount capacitor. The discontinuities created by the components at the electrode terminals further enhance the output quality of this oscillator. Fourth, the voltage-controlled oscillator designed according to the present invention uses cutting in different directions in the adjustable microstrip capacitance of the resonant circuit to subtly change the capacitance or make the capacitor itself inductive, thus To provide two-way frequency adjustment capability. Fifth, because the voltage-controlled oscillator manufactured according to the present invention has a fine-tuning function, the yield of manufacture can be greatly improved through fine-tuning. Sixth, the present invention uses microstrip capacitors to replace traditional surface mount capacitors, which further reduces material costs and effectively improves the competitiveness of product prices.

Description of drawings

Fig. 1 is a schematic structural diagram of a voltage-controlled oscillator;

2 is a schematic diagram of circuit components of a voltage-controlled oscillator circuit;

3 is a schematic diagram of a circuit board according to a first embodiment of the present invention;

4A is a cross-sectional exploded view of an adjustable capacitor structure according to the first embodiment of the present invention;

Fig. 4B is a schematic circuit diagram of Fig. 4A;

5A is a schematic diagram of adjusting an adjustable capacitor according to the first embodiment of the present invention;

5B is a schematic diagram of adjusting the adjustable capacitor according to the first embodiment of the present invention;

6A is a cross-sectional view of an adjustable capacitor structure made according to the second embodiment of the present invention;

FIG. 6B is a cross-sectional exploded view of the adjustable capacitor structure in FIG. 6A;

Figure 6C is a schematic diagram of a circuit embodiment;

7A is a schematic diagram of adjusting the adjustable capacitor according to the first embodiment of the present invention in the first direction;

7B is a schematic diagram of the first direction adjustment according to the first embodiment of the adjustable capacitor of the present invention;

FIG. 7C is a schematic diagram of the second direction adjustment according to the first embodiment of the present invention adjustable capacitor;

7D is a schematic diagram of adjusting the adjustable capacitor according to the first embodiment of the present invention in the second direction;

FIG. 8A is a schematic diagram according to a third embodiment of the present invention; and

FIG. 8B is a schematic diagram of various layer components according to the third embodiment of the present invention;

Wherein, the reference signs are explained as follows:

10 Voltage Controlled Oscillator 11 Resonant Circuit

13 Coupling circuit 15 Oscillation circuit

17 Control Voltage 20 Voltage Controlled Oscillator

21 Resonant circuit 211 Adjustable microstrip capacitor

23 Coupling circuit 231 Adjustable microstrip capacitor

25 oscillator circuit 27 control voltage

30 Voltage Controlled Oscillator 31 Resonant Circuit

32 The first conductive layer 33 Coupling circuit

331 Adjustable Microstrip Capacitor 3310 Upper Microstrip

33101 Connecting end 33103 Cutting track

3312 Lower Microstrip 3314 Conductive Material

34 insulating layer 36 second conductive layer

40 Voltage Controlled Oscillator 411 Adjustable Microstrip Capacitor

4110 Upper Microstrip 4112 Lower Microstrip

4116 Conductive material 41103 Cutting track

41105 cutting track 41107 cutting track

41109 cutting track 42 first conductive layer

43 Inductance 44 Insulation layer

441 Perforation 45 Oscillating circuit

46 Conductive layer 48 Insulation layer

481 Perforation 49 Inductance

Detailed ways

Please refer to FIG. 1 , which is a schematic structural diagram of a voltage controlled oscillator 10 . The VCO 10 uses an external control voltage 17 to adjust the output frequency of the oscillator 10 . As shown in FIG. 1 , the VCO 10 includes a resonant circuit 11 , a coupling circuit 13 , and an oscillating circuit 15 . The oscillation circuit 15 is used to stimulate oscillation and maintain the continuation of the oscillation signal, and the resonance circuit 11 can limit the oscillation frequency generated by the oscillation circuit 15 to limit the operating frequency range of the oscillator to a desired frequency range. The coupling circuit 13 is used to connect the resonance circuit 11 and the oscillation circuit 15 . In addition, adjusting the coupling circuit 13 can further adjust the coupling amount between the oscillation circuit 15 and the resonant circuit 11 to further achieve the purpose of phase noise adjustment.

Next, please refer to FIG. 2 , which is a schematic circuit diagram illustrating a voltage-controlled oscillator 20 . The output frequency of the voltage controlled oscillator 20 is adjusted by an external control voltage 27 . As shown in FIG. 2 , the voltage controlled oscillator 20 includes a resonance circuit 21 , a coupling circuit 23 and an oscillation circuit 25 .

In this schematic example, the resonant circuit 21 is composed of several capacitors, inductors, an adjustable microstrip capacitor 211 , and a voltage-adjustable varactor diode. The coupling circuit 23 is composed of another adjustable microstrip capacitor 231 . As for the oscillating circuit 25, it is composed of several capacitors, inductors, and a BJT. It must be pointed out that the voltage-controlled oscillator 20 drawn here is only for illustration, and various slightly different circuit structures can be used, which should still fall within the scope of the present invention.

The important features of the present invention include the proposed design and fine-tuning method for the adjustable capacitors 211, 231. It will be described with three embodiments below.

first embodiment

In this embodiment, the voltage-controlled oscillator installed on the circuit board of the electronic device is an adjustable series microstrip capacitor in the adjustment coupling circuit, such as the adjustable capacitor 231 in FIG. converter process, adjust its phase noise for work.

Please refer to FIG. 3 . FIG. 3 is a circuit board structure of a voltage-controlled oscillator 30 . As shown in FIG. 3 , the VCO 30 includes a resonant circuit 31 , a coupling circuit 33 and an oscillating circuit 35 . For the circuit structure of the resonant circuit 31 , the coupling circuit 33 and the oscillating circuit 35 , please refer to the circuit diagram shown in FIG. 2 .

First, a plurality of microstrips are formed by patterning the first conductive layer 32 . These microstrips are conductive and are used to connect the circuit components of the resonant circuit 31 , the coupling circuit 33 and the oscillating circuit 35 . Among these microstrips is included an upper microstrip 3310 to form part of the microstrip capacitance 331 of the coupling circuit 33 .

In addition, by patterning a second conductive layer 36 , at least a lower microstrip is formed on the second conductive layer 36 , and the lower microstrip overlaps with the upper microstrip 3310 of the first conductive layer 32 . Moreover, an insulating layer 34 is sandwiched between the first conductive layer 32 and the second conductive layer 36 . The insulating layer 34 has a perforation, and the conductive material is filled in the perforation, and by the conductive material, the lower microstrip that overlaps the upper microstrip 3310 of the second conductive layer 36 and the first conductive layer 32 can be connected to the first conductive layer 32. The oscillation circuit of the layer 32, so that the upper microstrip 3310, the lower microstrip and the insulating layer 32 together form an adjustable microstrip capacitor 331.

Next, use a laser or other cutting tools to partially cut the upper microstrip 3310 to change the capacitance of the adjustable capacitor 331, thereby changing the electrical properties of the coupling circuit and adjusting the phase noise of the voltage-controlled oscillator 30 to obtain the lowest phase noise output.

In order to illustrate the structure of the adjustable microstrip capacitor 331 more clearly, please refer to FIG. 4A , which is a schematic diagram of the combination of the voltage-controlled oscillator 30 in FIG. 3 .

As mentioned above, the adjustable microstrip capacitor 331 is a circuit component of the coupling circuit 33 of the voltage-controlled oscillator 30 , connected to the resonant circuit component 31 at one end 33101 , and connected to the oscillating circuit component 35 at the other end 33102 . The adjustable microstrip capacitor 331 is composed of an upper microstrip 3310 , an insulating layer 34 and a lower microstrip 3312 . The insulating layer 34 has a through hole 341 filled with a conductive material 3314 to connect the lower microstrip 3312 to the oscillation circuit component 35 . Therefore, from the structure of FIG. 4A , a schematic structural diagram of the voltage control circuit 30 shown in FIG. 4B can be obtained.

Next, please refer to FIG. 5A and FIG. 5B . These two figures illustrate two different adjustment states of the upper microstrip 3310 observed from the top view. In the process of manufacturing the voltage-controlled oscillator 30 , laser or other cutting tools can be used to cut the upper microstrip 3310 , such as the cutting track 33103 shown in FIGS. 5A and 5B . By cutting different positions of the upper microstrip 3310, the adjustable microstrip capacitor 331 can obtain different capacitances. For example, in the cutting track shown in FIG. 5A , compared with the cutting track shown in FIG. 5B , the former can make the adjustable microstrip capacitor 331 have a smaller capacitance value.

Since the adjustable microstrip capacitor 331 is placed in the coupling circuit of the voltage-controlled oscillator 30, when its capacitance changes, the amount of coupling between the oscillation circuit and the resonant circuit of the voltage-controlled oscillator will be changed. However, it shows different phase noise and output frequency. However, what is discussed in this embodiment is how to obtain the best coupling amount by adjusting the coupling capacitor to obtain the lowest phase noise output. If the frequency change may exceed The specification range should be matched with the second embodiment to compensate.

second embodiment

In this embodiment, the voltage-controlled oscillator installed on the circuit board of the electronic device is adjusted by adjusting the adjustable parallel microstrip capacitor in the resonant circuit, such as the adjustable microstrip capacitor 211 in Figure 2, to achieve In the process of controlling the oscillator, adjust its output frequency.

Please refer to FIG. 6A , which illustrates a circuit board structure and circuit of a voltage-controlled oscillator 40 . The VCO 40 includes three parts: a resonant circuit, a coupling circuit and an oscillating circuit. For the circuit structure of the resonant circuit, the coupling circuit and the oscillating circuit, please refer to the circuit diagram shown in FIG. 2 .

In this embodiment, its circuit structure is as follows. First, the first conductive layer 42 is patterned to form a plurality of microstrips. These microstrips are electrically conductive and are used to connect circuit components of resonant circuits, coupling circuits, and oscillator circuits. And, these microstrips include an upper microstrip 4110, which is located in the resonant circuit and becomes a part of the resonant circuit.

In addition, the second conductive layer 46 is patterned so that at least one lower microstrip of the second conductive layer 46 is grounded and overlaps with the upper microstrip 4110 of the first conductive layer 42 . Moreover, an insulating layer 44 is disposed between the first conductive layer 42 and the second conductive layer 46 . The insulating layer 44 has a perforation 481, and the conductive material 4116 is filled in the perforation 481, and by the conductive material 4116, the lower microstrip that overlaps the second conductive layer 46 and the first conductive layer 42 can be connected to the first conductive layer 42. The oscillating circuit, so that the upper microstrip 4110, the lower microstrip and the insulating layer 44 jointly form an adjustable microstrip capacitor 411, and the adjustable microstrip capacitor is placed in the resonant circuit.

Next, decide whether the output frequency of the VCO should be adjusted up or down. As shown in Figure 6B, when it is decided to lower the output frequency, laser or other cutting tools are used to cut the upper microstrip in a first direction A. At this time, the microstrip capacitor will present an electric current due to the increase of the electric wave transmission path. Inductive, thereby reducing the resonant frequency of the resonant circuit. Conversely, if it is decided to increase the output frequency, laser or other cutting tools are used to cut the upper microstrip in a second direction B, thereby reducing the capacitance of the microstrip capacitor 411, thereby increasing the resonance of the resonant circuit frequency purpose. By the above method, the output oscillation frequency of the voltage controlled oscillator can be adjusted.

In order to illustrate the structure of the adjustable microstrip capacitor more clearly, please refer to FIG. 6B , which illustrates the structure of the adjustable capacitor 411 . Since the structure of the adjustable capacitor 411 is similar to that of the adjustable capacitor 331 of the first embodiment, in the following description, the reference numerals are the same as before, and their meanings can refer to the previous description.

The adjustable capacitor 411 is composed of an upper microstrip 4110, a lower microstrip 4112 and an insulating layer 44 sandwiched between them. The upper microstrip 4110 and the lower microstrip 4112 are formed by patterning the first conductive layer 42 and the second conductive layer 46 respectively. In this example, the upper microstrip 4110 of the adjustable capacitor 411 is connected to the inductor 49 and the inductor 43 , and the other end is connected to the ground through the conductive material 4116 in the through hole 481 of the insulating layer 48 . In addition, please refer to FIG. 6C , which illustrates a schematic circuit diagram of an adjustable microstrip capacitor 411 connected to the inductor 49 and connected in parallel with the inductor 43 .

Next, please refer to FIG. 7A and FIG. 7B , which illustrate that the upper microstrip 4110 of the adjustable microstrip capacitor 411 is cut in the first direction A, thereby making the adjustable microstrip capacitor 411 appear inductive and changing the resonance circuit thereof. Resonant frequency, and then adjust the output frequency range of the voltage controlled oscillator.

For example, if the trace 41103 of FIG. 7A is cut out on the upper microstrip 4110 with a laser or other cutting tools, the output frequency of the VCO can be reduced. If you want to lower the output frequency of the voltage-controlled oscillator, you can cut out the track 41105 as shown in Figure 7B.

Next, please refer to FIG. 7C and FIG. 7D. These two figures illustrate that cutting the upper microstrip 4110 of the adjustable microstrip capacitor 411 in the second direction B cuts out the trace 41107 of FIG. 7C and the trace 41109 of FIG. The capacitance value of the tuning capacitor 411 makes the resonant frequency rise due to the reduction of the parallel capacitance. If the trace 41109 of FIG. 7D is cut out on the upper microstrip 4110 with a laser or other cutting tools, the output frequency of the voltage-controlled oscillator can be increased even higher.

third embodiment

In addition to the above-mentioned two embodiments where the adjustable microstrip capacitors are arranged on the coupling circuit and the resonant circuit respectively, another embodiment is to arrange the adjustable microstrip capacitors on the coupling circuit and the resonant circuit at the same time.

That is to say, the third embodiment is a combination of the first embodiment and the second embodiment. Please refer to FIG. 8A , which shows a circuit board combining the first embodiment and the second embodiment. On this circuit board, there are adjustable microstrip capacitors 211 and 231 composed of microstrips, respectively arranged in the coupling circuit and the resonant circuit of the voltage controlled oscillator. Wherein, the adjustable microstrip capacitor 211 can be cut at different positions to provide different coupling capacitances to obtain the lowest phase noise. As for the adjustable microstrip capacitor 231, it can be cut in the X direction and the Y direction, so as to precisely adjust the output frequency of the VCO.

In addition, please refer to FIG. 8B , which shows a three-dimensional exploded view of the circuit board in FIG. 8A . From this and in conjunction with the foregoing description, the technology of the present invention can be grasped more clearly.

Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any equivalent structural transformation made by any person of ordinary skill in the art without departing from the spirit and scope of the present invention, All are included in the patent scope of the present invention.

Claims (10)

1. An electronic device with a fine-tunable voltage-controlled oscillator, characterized in that it comprises: A voltage-controlled oscillator has a resonant circuit, a coupling circuit and an oscillating circuit; a first patterned conductive layer for arranging the resonant circuit, the coupling circuit and the oscillating circuit, and the first patterned conductive layer has a plurality of microstrips for connecting the resonant circuit, the coupling circuit and the oscillating circuit, And the plurality of microstrips include a first upper microstrip formed in the coupling circuit; A second patterned conductive layer having a first lower microstrip overlapping the first upper microstrip; A first insulating layer, placed between the first conductive layer and the second conductive layer, and the insulating layer includes a first through hole, wherein the first through hole is filled with a conductive material, and the through hole Connecting the first lower microstrip to the oscillating circuit, so that the first upper microstrip, the first lower microstrip and the first insulating layer together form a first adjustable microstrip capacitor in the coupling circuit, wherein, The capacitance value of the first adjustable microstrip capacitor can be changed by partially cutting the first upper microstrip, thereby also fine-tuning the VCO to obtain the lowest phase noise. 2. The electronic device according to claim 1, wherein one end of the first adjustable microstrip capacitor is connected to the resonant circuit, and the other end of the first adjustable microstrip capacitor is connected to the oscillating circuit . 3. The electronic device according to claim 2, wherein the microstrip of the first conductive layer further comprises a second upper microstrip in the resonant circuit, and the second conductive layer further comprises a The second lower microstrip overlapping with the second upper microstrip, and the second upper microstrip, the first insulating layer and the second lower microstrip form a second adjustable microstrip capacitance, and the second adjustable The tuned microstrip capacitance is connected to an inductance in the resonant circuit, thereby changing the circuit characteristics of the resonant circuit by partially cutting the second upper microstrip, wherein when cutting the second upper microstrip in a first direction , the second adjustable microstrip capacitor exhibits inductance to lower a resonant frequency of the resonant circuit, and when cutting the second upper microstrip in a second direction, the capacitance of the second adjustable microstrip capacitor The value is decreased to increase the resonant frequency of the resonant circuit, thereby also providing a fine-tuning range of the oscillating frequency generated by the voltage-controlled oscillator. 4. The electronic device according to claim 3, wherein one end of the second adjustable microstrip capacitor is connected to the inductor, and the other end is connected to ground. 5. The electronic device according to claim 4, comprising a third patterned conductive layer and a second insulating layer, wherein the second insulating layer is disposed between the third conductive layer and the second conductive layer between, and the second insulating layer includes a second through hole, the second through hole is filled with conductive material, and the third conductive layer is connected to ground, so as to provide the circuit components of the first conductive layer and the second conductive layer grounding. 6. An electronic device with a fine-tunable voltage-controlled oscillator, characterized in that it comprises: A voltage-controlled oscillator has a resonant circuit, a coupling circuit and an oscillating circuit; a first patterned conductive layer for arranging the resonant circuit, the coupling circuit and the oscillating circuit, and the first patterned conductive layer has a plurality of microstrips for connecting the resonant circuit, the coupling circuit and the oscillating circuit, And the plurality of microstrips include a first upper microstrip formed in the resonant circuit; A second patterned conductive layer having a first lower microstrip overlapping the first upper microstrip; An insulating layer, placed between the first conductive layer and the second conductive layer, so that the first upper microstrip, the first lower microstrip and the insulating layer together constitute a first adjustable a microstrip capacitance, the first adjustable microstrip capacitance is connected to an inductance of the resonant circuit, wherein when the first upper microstrip is cut in a first direction, the adjustable microstrip capacitance exhibits inductance, to reduce a resonant frequency of the resonant circuit, and when cutting the first upper microstrip in a second direction, the capacitance value of the adjustable capacitor decreases to increase the resonant frequency of the resonant circuit, thereby fine-tuning the The range of oscillation frequencies generated by a voltage controlled oscillator. 7. The electronic device as claimed in claim 6, wherein one end of the first adjustable microstrip capacitor is connected to the inductor, and the other end is connected to ground. 8. The electronic device according to claim 7, further comprising a third patterned conductive layer and a second insulating layer, wherein the second insulating layer is arranged on the third conductive layer and the second conductive layer and the second insulating layer includes a through hole filled with conductive material, and the third conductive layer is connected to ground to provide grounding of the circuit components of the first conductive layer and the second conductive layer. 9. The electronic device according to claim 8, wherein the microstrip of the first conductive layer further comprises a second upper microstrip in the coupling circuit, and the second conductive layer further comprises forming a The second lower microstrip overlapping with the second upper microstrip makes the second upper microstrip, the first insulating layer and the second lower microstrip form a second adjustable microstrip capacitor, thus, the coupling The capacitance value of the second adjustable microstrip capacitor of the circuit can be changed by partially cutting the second upper microstrip, thereby fine-tuning the voltage-controlled oscillator to obtain the lowest phase noise. 10. The electronic device according to claim 9, wherein one end of the second adjustable microstrip capacitor is connected to the resonant circuit, and the other end of the second adjustable microstrip capacitor is connected to the oscillating circuit .

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