JPH07235640A - Lc composite element - Google Patents

Abstract

PURPOSE:To provide an LC composite element which can be lessened in size and formed as a component part of an LSI or the like. CONSTITUTION:An LC composite device is composed of ten stripe-like PN junction layers 30 formed on an N-Si substrate 10a, nine switches 38 used for connecting these PN junctions layers 30 in parallel, and an inductor conductor 24a formed above the PN junction layers sandwiching an insulating layer 22 with them. The PN junction layers 30 are stripe-like and small in width, so that a large eddy current is never generated in the surfaces of the PN junction layers 30 even if an electric current flows through the inductor conductor 24a to produce a magnetic flux, and an inductor is never impeded in its function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LC composite element having at least a coil and a capacitor formed on a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, two insulating substrates have been used which face each other.
A coil is formed by forming two electrodes to form a capacitor, forming spiral electrodes on both sides of this insulating substrate, and connecting the inner ends of these two spiral electrodes through the insulating substrate. Formed LC composite parts are known.

In such a conventional LC composite component, a material such as ceramic, plastic, or mica is used as an insulating substrate that serves as a dielectric, and electrodes are formed opposite to each other on both sides of the insulating substrate by a printing process. .

[0004]

By the way, the above-mentioned conventional LC composite component is one in which a capacitor and a coil are arranged adjacent to each other on an insulating substrate, and an electrode for forming the capacitor and a spiral shape for forming the coil are formed. There is a problem that miniaturization is difficult because the electrodes cannot be formed so as to overlap each other. For example, when the electrode of the capacitor is arranged so as to overlap the spiral electrode, the magnetic flux generated by the spiral electrode is obstructed, so that the spiral electrode does not function as a coil. Therefore, in order to form a capacitor having a large capacitance together with the coil, it is necessary to connect those formed separately to form an LC composite component.

Further, since the above-mentioned conventional LC composite component is formed by disposing electrodes facing each other with an insulating substrate sandwiched between them, it is difficult to form it as a part of LSI or the like. Therefore, when this LC composite component is used, it is necessary to perform wiring separately from the LSI or the like, which causes a problem that the wiring and the like are troublesome.

Therefore, the present invention was created in view of the above points, can be miniaturized, and has an LS.
It is an object of the present invention to provide an LC composite element that can be formed as a part of I or the like.

[0007]

In order to solve the above-mentioned problems, the LC composite element according to claim 1 is formed on a semiconductor substrate and serves as a capacitor having a predetermined capacitance when a reverse bias voltage is applied. A plurality of functioning elongated pn junction layers, an inductor conductor formed at a position corresponding to the pn junction layers with an insulating layer sandwiched on the semiconductor substrate, and the pn junction layers are connected in parallel. And a connecting portion for connecting the capacitor and the inductor to each other on the semiconductor substrate.

A composite element according to a second aspect is the LC composite element according to the first aspect, which includes a plurality of semiconductor switches which connect the pn junction layers in parallel by turning on the connection instead of the connecting portion. Therefore, by sequentially switching the connection state of each of these semiconductor switches,
It is characterized in that the number of the pn junction layers connected in parallel is switched to variably control the capacitance formed by these pn junction layers.

According to a third aspect of the present invention, there is provided the LC composite element according to the first or second aspect, wherein the capacitance of each of the pn junction layers is varied by applying a variable reverse bias voltage to the pn junction layer. It is characterized by controlling to.

The LC composite element of claim 4 is the same as that of claims 1 to 3.
In any one of the LC composite elements described above, the inductor conductor has a spiral shape.

An LC element according to a fifth aspect is the LC composite element according to any of the first to third aspects, wherein the inductor conductor has a meandering shape.

An LC element according to a sixth aspect is the LC composite element according to any of the second to fifth aspects, wherein the semiconductor switch is formed by a MOS transistor.

The LC composite element of claim 7 is the same as that of claim 2-5.
In any one of the LC composite element of the above, the semiconductor switch is an n-channel MOS transistor and a p-channel MO transistor.
It is characterized in that it is formed by a transmission gate using an S transistor in parallel.

[0014]

According to the invention of claim 1, an LC composite element is formed by stacking inductor conductors on a plurality of elongated pn junction layers formed on a semiconductor substrate. In general,
When the electrode plate or the like is formed close to the inductor conductor, the magnetic flux generated by the inductor conductor is obstructed by the eddy current generated on the surface of the electrode plate or the like, so that the inductor conductor does not function as a coil. However,
Since the pn junction layer of the present invention is formed in a long shape and is connected in parallel by the connecting portion, the eddy current generated on the surface of the p region or the n region can be suppressed to the minimum, and the inductor conductor also It can function as a coil. Therefore, the pn junction layer functioning as a capacitor and the inductor conductor can be formed so as to overlap with each other on the semiconductor substrate, and the element can be downsized.

Further, since the pn junction layer and the inductor conductor are formed inside or on the surface of the semiconductor substrate, they can be formed as a part of LSI or the like.

According to the second aspect of the invention, the plurality of pn layers described above are connected in parallel by a connecting portion, but this connection is made using a plurality of semiconductor switches. Therefore, by sequentially switching the connection state of these semiconductor switches, the number of pn junction layers connected in parallel is switched, and the capacitance of the capacitor formed together with the inductor conductor can be variably controlled.

According to the invention of claim 3, the reverse bias voltage applied to the above-mentioned pn junction layer is made variable, whereby each of the pn junction layers functions as a variable capacitance diode, so that they are connected in parallel. The capacitance of the capacitor formed by the formed pn junction layer can be continuously changed. In particular, the capacity can be continuously changed over a wide range by combining with the switching control of the semiconductor switch described above.

Further, the invention of claim 4 is to effectively use the magnetic flux generated by the inductor conductor by forming the above-mentioned inductor conductor into a spiral shape. In general, an inductor having a large inductance is formed by winding a conductor in a coil shape. Therefore, by forming the above-mentioned inductor conductor in a spiral shape, a large inductance can be provided, and the inductor is used in a wide frequency band. Possible LC composite elements can be formed.

On the other hand, according to the invention of claim 5, the above-mentioned inductor conductor has a meandering shape. As described above, the inductor is generally formed by winding the inductor conductor in a coil shape. However, when used in a high frequency band, a small inductance is sufficient, and thus it can be formed in a meandering shape. By thus forming the inductor conductor in a meandering shape, both ends of the inductor conductor are located in the outer peripheral portion, so that it is easy to lead out the electrodes and wire.

According to a sixth aspect of the invention, the semiconductor switch described above is formed by a MOS transistor. That is, when the switch is configured by the MOS transistor, it has no directivity in the ON state, which is particularly convenient for parallel connection of the pn junction layers to which an AC signal is applied. The pn junction layers connected in parallel function as a capacitor, and charge and discharge are repeated through these p regions or n regions. Therefore, a directional switch such as a switch using a bipolar transistor is used. In some cases, p connected in parallel
The movement of carriers is hindered between the regions or between the n regions, which hinders the operation. However, the switch of the MOS transistor does not have such an adverse effect.

Further, the invention of claim 7 further limits the above-mentioned semiconductor switch, and is formed by a transmission gate using an n-channel MOS transistor and a p-channel MOS transistor in parallel. Therefore, no matter what voltage level signal is input to the capacitor formed by the pn junction layer, the on resistances of the semiconductor switches are substantially equal, and stable element characteristics can be provided.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An LC composite device of one embodiment to which the present invention is applied will be specifically described below with reference to the drawings.

FIG. 1 shows an LC of an embodiment to which the present invention is applied.
It is a figure which shows the outline | summary of a composite element.

As shown in the figure, the LC composite element 100 of the present embodiment is formed with a capacitor section 20 formed on the front surface side of the semiconductor substrate 10 and an insulating layer 22 above the capacitor section 20. And the inductor portion 24 that has been formed.

The capacitor section 20 is composed of a plurality of long pn junction layers. The inductor portion 24 is made of a conductive thin film such as metal or polysilicon formed on the surface of the insulating layer 22 by a printing technique or the like, and has a spiral shape. These details will be described below.

FIG. 2 is a plan view showing the detailed structure of the LC composite device 100 of this embodiment. Further, FIG. 3 is an enlarged cross-sectional view taken along the line AA of the LC composite element shown in FIG. 2, and FIG.
It is a -B line expanded sectional view.

As shown in these figures, the LC composite element 100 of the present embodiment has an elongated shape 10 having almost the same structure.
It has a pn junction layer 30-1 to 30-10 of a book, and a p-region among them is connected by switches 38-1 to 38-9 of a MOS transistor as needed to form a capacitor. The area of the pn junction is changed stepwise. The ten pn junction layers 30-
Since each of 1 to 30-10 has substantially the same shape, one of them will be described in detail, and the difference will be described each time.

The pn junction layer 30-1 is formed by the p region 32-1 and the n region 34-1. Here, the p-region 32-1 having the elongated shape is formed in the vicinity of the surface of the semiconductor substrate 10, specifically, the n-type silicon substrate (n-Si substrate) 10a, and the part thereof is elongated. An n region 34-1 having a shape is formed. The p region 32-1 and the n region 34-1 form the pn junction layer 30-.
1 is formed, and functions as a variable capacitance diode whose capacitance can be changed by applying a variable reverse bias voltage to the pn junction layer 30-1.

In the ten pn junction layers 30-1 to 30-10 having such a structure, one end of each of the ten elongated n regions 34-1 to 34-10 has a connection electrode 12. Are electrically connected by. Then, the pn junction layers are connected in parallel by electrically connecting the opposite one ends of the p regions 32-1 to 32-10 having a long shape by the switches 38-1 to 38-9. ing.

The connection electrode 12 is not necessarily formed in the n region 34.
It is provided on one end side of the connection electrode 12 and the switch 3
It is not necessary to provide 8-1 to 38-10 at separate positions near both ends of the pn junction layer 30. For example, the connection electrode 12 is provided between the winding parts of the inductor conductor 24a shown in FIG.
May be provided, or the connection electrode 12 and the switch 38 may be provided adjacent to each other at substantially the same position. By providing the connection electrode 12 between the inductor conductors 24a, the n-Si substrate 10a can be effectively used.

The switch 38-1 is formed by arranging a control electrode 36-1 so as to overlap the insulating layer 22 on a part of one end of each of two adjacent p regions 32-1 and 32-2. Has been done. That is, this switch 38-
Reference numeral 1 is a switch having a MOS structure, and a control electrode 36
-1 corresponds to the gate electrode, and one end portions of the p regions 32-1 and 32-2 correspond to the source and drain, respectively. By applying a predetermined voltage to the control electrode 36-1, the corresponding p-region A channel is formed between the regions 32-1 and 32-2, and an electrical connection is made by this channel. In this way, each of the switches 38-1 to 38-9 is configured by the two adjacent p regions and the control electrode arranged between them so as to partially overlap with each other. Therefore, the number of pn layers connected in parallel can be switched by sequentially switching the connection of adjacent switches to the ON state.

Further, the pn junction layer 30 located substantially at the center
One end of the p region 32-5 of −5 is extended to the outside, and the terminal electrode 40 is connected to this extended portion. On the other hand, the inductor conductor 2 forming the inductor portion 24 is formed in the substantially central portion of the n region 34-5 of the pn junction layer 30-5.
4a is electrically connected to one end (end on the inner peripheral side). The other end (outer peripheral end) of the inductor conductor 24a functions as the terminal electrode 42.

FIG. 5 is a diagram showing an equivalent circuit of the above-mentioned capacitor section 20. In the figure, VC1 is a variable capacitance diode (varicap) composed of a pn junction layer 30-1. Similarly, each of VC2 to VC10 is a variable capacitance diode configured by each of the pn junction layers 30-2 to 30-10.

When the capacitor section 20 of this embodiment having the above-mentioned structure and equivalent circuit is used with the minimum capacitance, all the switches 38-1 to 38-9 shown in FIG. 5 are controlled to be in the off state. In the case of such a connection state, only the variable capacitance diode VC5 constituted by the pn junction layer 30-5 located substantially in the center becomes effective, so that the capacitance becomes the minimum.

In such a connected state, the switch 38-5 is then turned on. This switching is performed by applying a predetermined voltage to the control electrode 36-5 shown in FIG. At this time, since VC5 and VC6 are connected in parallel, the capacity is significantly increased as compared with the capacity of only VC5.

In this way, by sequentially turning on the switches close to VC5, the number of pn junction layers connected in parallel increases, so that the junction area for forming a capacitor also increases stepwise. As a result, the capacity changes stepwise over a wide range.

Further, the respective capacitances of the variable capacitance diodes VC1 to VC10 described above are continuously changed by variably controlling the reverse bias voltage to be applied, so that the variable reverse bias voltages as shown in FIG. By applying a voltage and combining switching of the switches 38-1 to 38-9, it is possible to continuously change the capacitance over a wide range.

FIG. 6 is a diagram showing an overall equivalent circuit of the LC composite device of this embodiment. The LC composite element of the present embodiment, the detailed structure of which is shown in FIG. 2, is one in which one end side of the inductor conductor 24a is connected in series with the capacitor section 20, and the series LC resonance circuit shown in FIG. Is forming.

The connection state between the inductor conductor 24a and the capacitor section 20 can be changed. For example, by extending the connection electrode 12 and using the extended portion as a terminal electrode and electrically connecting the two terminal electrodes 40 and 42 to use as one terminal electrode,
The parallel LC resonance circuit shown in FIG. 6B can be used.

As described above, the LC composite device 10 of this embodiment is used.
0 forms ten pn junction layers 30-1 to 30-1-having a long shape on the n-Si substrate 10a, and these are connected in parallel by switches 38-1 to 38-9 as necessary. Together with these pn junction layers 30-1 to 30-10
Insulating layer 22 is sandwiched above inductor conductor 24
a is formed.

Since each pn junction layer is formed in a long shape, the eddy current generated by the magnetic flux of the inductor conductor 24a can be suppressed to a minimum, and the operation when functioning as an inductor is not hindered. As a result, as described above, it is possible to form the capacitor section 20 and the inductor section 24 on the same portion of the n-Si substrate 10a so as to be miniaturized. Further, since it can be formed on the n-Si substrate 10a, it can be formed as a part of an LSI or the like. In addition, even if it is not formed as a part of LSI or the like,
It is possible to form a plurality of LC composite elements 100 on the n-Si substrate 10a and separate them at the end, and it is possible to easily carry out mass production using semiconductor manufacturing technology.

Further, the LC composite element 100 of this embodiment is
The capacitor section 20 is composed of ten pn junction layers 30-1 to 30-1.
A variable capacitance diode is configured by connecting 30-10 in parallel as necessary. Therefore, by switching each of the switches 38-1 to 38-9 to the ON state in a predetermined order, the number of pn junction layers connected in parallel can be switched in a stepwise manner, and the capacitance of the capacitor section 20 over a wide range. Can be variably controlled. Further, by changing the reverse bias voltage applied to each pn junction layer 30, each pn junction layer 30 is changed.
Since it is possible to continuously change the capacity, the capacity can be continuously changed over a wide range by combining the switch switching control and the reverse bias voltage variable control described above.

FIG. 7 is a diagram showing an example of a control circuit most suitable for switching the switches of the capacitor section 20 of this embodiment. The capacitor unit 2 of the present embodiment whose equivalent circuit is shown in FIG.
For 0, it is necessary to sequentially switch the switches 38 for switching the connection state at a predetermined timing.

The circuit shown in FIG. 7 has one control voltage Vc.
By continuously changing (<0), the switch 38 is sequentially turned on and controlled according to the voltage level. In the figure, 10 resistors 5
0 to 59 are for dividing the control voltage Vc, and each divided voltage is applied to each of the nine switching transistors 61 to 69. Further, pull-down resistors 71 to 79 are connected to the respective switching transistors 61 to 69 so that a predetermined voltage can be taken out when the respective switching transistors are turned on.

In the above circuit, when the control voltage Vc gradually decreases (when the absolute value of Vc increases), only the switching transistor 61 is turned on first. At this time, the potential of the one end of the pull-down resistor 71 decreases, so that a predetermined voltage is applied to the control electrode 36-5 connected to this one end side, and only the switch 38-5 is turned on. If the control voltage Vc further decreases, then 2
Since the second switching transistor 62 is also turned on, the switch 38-4 connected to one end of the pull-down resistor 72 is also turned on. In this way, as the control voltage Vc further decreases, the switching transistors 63 and onward are sequentially turned on, and the corresponding switches are turned on.

Therefore, by decreasing the control voltage Vc, the number of pn junction layers connected in parallel with the pn junction layer 30-5 located in the substantially central portion gradually increases. Moreover, by changing the reverse bias voltage applied to each pn junction layer, the capacitance of the pn junction layers connected in parallel can be continuously changed over a wide range.

FIG. 8 is a diagram showing a modification of this embodiment. The LC composite element shown in the figure has a configuration in which each of the switches 38-1 to 38-9 shown in FIG. 2 is replaced with a transmission gate including an n-channel MOS switch and a p-channel MOS switch.

As shown in FIG. 8, a p-well 80 is formed in a portion near the surface of the n-Si substrate 10a, and ten n regions 82-1 and 82 are formed in a portion of the p-well 80. −
2, ... are formed. The control electrode 84- is sandwiched so as to sandwich the insulating layer 22 so as to partially overlap the adjacent n region.
1 and the like are formed, and a switch formed by an n-channel MOS transistor is formed. Further, a part of the p region 32-1 and the like described above and a part of the n region 82-1 and the like are connected by the connection electrode 86, and a transmission gate including an n-channel MOS transistor and a p-channel MOS transistor is formed. Has been done. As described above, by forming the switch with the transmission gate, a stable on-resistance can always be obtained by the pair of p-channel and n-channel MOS switches.
The characteristics of the entire capacitor unit 20 are also stable.

FIG. 9 is a diagram showing still another modification of the present embodiment. In the LC composite element shown in the figure, two p regions 90 and 92 are formed in a part of the n-Si substrate 10a shown in FIG. 2, and the insulating layer 22 is formed so as to connect them.
A gate electrode 94 is formed so as to sandwich it. These two p regions 90 and 92 function as a source and a drain, and these form a MOS transistor in which the gate electrode 94 has an elongated shape. Therefore, the channel 96 formed on the n-Si substrate 10a facing the gate electrode 94 functions as a low antibody whose resistance value can be changed by variably controlling the voltage level applied to the gate electrode 94.

In the modification shown in FIG. 9, the inductor conductor 2
4a has the above-mentioned channel 94 connected in series, and its equivalent circuit is shown in FIG. 6 (C).

As described above, the LC composite element of this embodiment is
Since it is formed by using the n-Si substrate 10a, it can be integrally formed with other passive elements such as resistors and active elements.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

For example, in the above-mentioned embodiments, the case where ten pn junction layers having a long shape are formed has been described for the sake of simplicity, but in order to suppress the generation of eddy currents, It is desirable to reduce the width of each pn junction layer to increase the number.

Further, the above-mentioned LC composite element 100 has the n regions 34-1 to 34-10 each having a long shape.
One end side is connected by the connection electrode 12, and the other end sides of the p regions 32-1 to 32-10 having a long shape are connected by the switches 38-1 to 38-9. The side may be always connected by the connection electrode. In this case, the number of pn junction layers connected in parallel is fixed, and the capacitance value is variably controlled by changing the reverse bias voltage applied to each of the n region 34 and the p region 32. The variable range is narrower than that of the LC composite element 100 described above. However, there is no change in that the capacitor and the inductor can be formed on the same semiconductor substrate in an overlapping manner, and there is no change in that the elements can be miniaturized or can be formed as part of an LSI or the like. If it is not necessary to change the capacitance value, p
The reverse bias voltage applied to the n-junction layer may be fixed.

Further, the above-mentioned LC composite element 100 has a long linear pn junction layer 30-1 to 30.
I arranged each of -10 in parallel,
As long as it has a long shape and can reduce the eddy current generated on its surface, for example, when forming a pn junction layer having a long shape in an L shape, in a U shape, or in a curved shape. It may be formed in a shape.

In this embodiment, one capacitor unit 2
The case where the resonance circuit in which 0 and the inductor section 24 are connected in series or in parallel is configured has been described as an example, but the present invention can be applied to the case where the capacitor section 20 and the inductor 24 at least partially overlap each other. Therefore, by reducing the number of pn junction layers shown in FIG.
When the n-junction layer and the inductor conductor 24a partially correspond to each other, or when the 10 pn-junction layers in FIG. It may be connected to the conductor 24a. Further, two or a plurality of inductor conductors 24a formed so as to overlap with the pn junction layer may be separately formed in a spiral shape.

Further, although the LC resonance circuit has been described as an example of the simplest case in the above-mentioned embodiment, it is possible to arbitrarily form other than the resonance circuit by combining the capacitor section and the inductor section. FIG. 11 is a diagram illustrating a circuit example other than the resonance circuit. 2A is an equivalent circuit when a resonance type low-pass filter or high-pass filter including a capacitor and an inductor is formed by extending the end portion of the connection electrode 12 shown in FIG. 2 to form a terminal electrode. is there. Further, FIG. 2B shows two inductor conductors formed on each pn junction layer shown in FIG. 2 and connected in a ring shape. Similarly, in FIGS. 11C to 11F, a plurality of inductor conductors are formed, or in addition, a plurality of pn junction layers connected in parallel are divided into two to form a plurality of capacitors or inductors. The connection method can be arbitrarily set by changing the shape of the inductor conductor, the connection electrode, or the like. In particular, by forming two spiral inductor conductors 24a as shown in FIG. 2 concentrically, it is possible to form an air-core transformer without a magnetic core.
The circuit shown in (G) can also be used.

Further, although the inductor conductor 24a forming the inductor portion 24 is formed in the spiral shape in the above-mentioned embodiment, it may be replaced by the meandering inductor conductor shown in FIG. Generally, the inductor conductor functions as an inductor having a predetermined inductance when it is formed in a spiral shape. However, when the value of this inductance is relatively small, it is not always necessary to form the spiral shape and it is formed in a meandering shape. You can also When the inductor conductor is formed in a meandering shape in this manner, each meandering portion functions as an inductor of about 1/2 turn, and an inductor in which they are connected in series is formed. When the inductor conductor has a meandering shape, the inductance is smaller than that when it has a spiral shape. However, when the band of the signal used is limited to a high frequency, the inductor conductor has a meandering shape as shown in FIG. Will also work effectively.

In the above-mentioned embodiment, the case where the device is formed on the n-type silicon substrate has been described as an example, but a p-type silicon substrate or another material such as GaAs may be used.

Further, in the above-mentioned embodiment, as shown in FIG. 5, when it is attempted to connect the pn junction layers separated from the pn junction layer 30-5 located substantially in the center in parallel, the connections are made through a plurality of switches. This will increase the connection resistance. Therefore, nine switches that can individually connect the p region 32-5 and the other pn regions 32-1 to 32-4 and 32-6 to 32-10 are provided. When one (arbitrary) switch is turned on, the corresponding p region 32 (except 32-5) and the p region 32-5 may be connected. In this case, if an attempt is made to increase the number of pn junction layers in parallel, the number of switches to be turned on is increased, and this point is no different from the embodiment shown in FIG.

[0061]

As described above, according to the first aspect of the present invention, since each of the plurality of pn junction layers is formed in a long shape, the magnetic flux generated by the inductor conductor causes p
The eddy currents generated on the respective surfaces of the n-junction layer can be suppressed to a minimum, whereby the capacitor and the inductor can be formed on the semiconductor substrate so as to be miniaturized. Further, since it is integrally molded on the semiconductor substrate, it can be formed as a part of LSI or the like.

According to the second aspect of the invention, the pn junction layers are connected in parallel by the semiconductor switch, and the pn junction layers are connected in parallel by changing the connection state of the semiconductor switches as needed. It is also possible to variably control the capacitance of the capacitor by switching the number of the capacitors.

According to the third aspect of the invention, the capacitance of the capacitor can be continuously changed by variably controlling the reverse bias voltage applied to each pn junction layer forming the capacitor.

Further, according to the invention of claim 4, the inductor conductor is formed in a spiral shape so that a large inductance can be provided, and the LC composite element can be used in a wide frequency band, particularly in a low frequency region. be able to.

According to the fifth aspect of the present invention, by forming the inductor conductor in a meandering shape, it is possible to provide an LC composite element that can be used in a high frequency region. In this case, since both ends of the inductor conductor are located on the outer peripheral portion, it is easy to lead out the electrodes and wire.

According to the sixth aspect of the invention, since the semiconductor switch for connecting the pn junction layers in parallel is formed by the MOS transistor and has no directivity in the ON state, an AC signal is particularly applied. It is possible to adopt a convenient configuration for parallel connection of the pn junction layers.

According to the invention of claim 7, the semiconductor switch comprises an n-channel MOS transistor and a p-channel M transistor.
Since it is formed of a transmission gate using an OS transistor in parallel, it has stable element characteristics.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an LC composite element of one embodiment to which the present invention is applied.

FIG. 2 is a plan view showing a detailed structure of the LC composite element of FIG.

3 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 4 is an enlarged sectional view taken along line BB of FIG.

FIG. 5 is a diagram showing an equivalent circuit of a capacitor section.

FIG. 6 is a diagram showing an equivalent circuit of the LC composite element of the present embodiment.

FIG. 7 is a diagram showing a circuit for performing switch control of switches.

FIG. 8 is a diagram showing a modification of the present embodiment.

FIG. 9 is a diagram showing another modification of the present embodiment.

FIG. 10 is a diagram showing an inductor conductor formed in a meandering shape.

FIG. 11 is an explanatory diagram of a case where another circuit is formed by combining a capacitor and an inductor.

[Explanation of symbols]

 10 semiconductor substrate 12 connection electrode 20 capacitor part 22 insulating layer 24 inductor part 30 pn junction layer 32 p region 34 n region 36 control electrode 38 switch 40, 42 terminal electrode

Claims (7)

[Claims] 1. A plurality of elongated pn junction layers formed on a semiconductor substrate and functioning as capacitors having a predetermined capacitance when a reverse bias voltage is applied, and at a position corresponding to the pn junction layers. And an inductor conductor formed on the semiconductor substrate with an insulating layer sandwiched between the inductor conductor and a connecting portion for connecting the pn junction layers in parallel, and a capacitor and an inductor are formed on the semiconductor substrate in an overlapping manner. An LC composite device characterized by the above. 2. The semiconductor device according to claim 1, further comprising a plurality of semiconductor switches that connect the pn junction layers in parallel by turning on the connection instead of the connecting portion, and connect each of these semiconductor switches. By sequentially switching the states, the number of the pn junction layers connected in parallel is switched, and the capacitance formed by these pn junction layers is variably controlled.
C composite element. 3. The LC composite device according to claim 1, wherein the capacitance of each of the pn junction layers is variably controlled by applying a variable reverse bias voltage to the pn junction layers. . 4. The LC composite element according to claim 1, wherein the inductor conductor has a spiral shape. 5. The LC composite element according to claim 1, wherein the inductor conductor has a meandering shape. 6. The LC composite element according to claim 2, wherein the semiconductor switch is formed of a MOS transistor. 7. The LC composite element according to claim 2, wherein the semiconductor switch is formed by a transmission gate using an n-channel MOS transistor and a p-channel MOS transistor in parallel.