JP4249595B2 - High frequency switch circuit and high frequency switch parts - Google Patents

Description

  The present invention relates to a high-frequency switch circuit incorporated in a communication device such as a mobile phone and used for switching a signal path, and a high-frequency switch component using the same.

  Conventionally, a high-frequency switch circuit has been used to alternately switch transmission / reception of a transmission signal and a reception signal in a communication device or the like.

  FIG. 7 is an equivalent circuit diagram showing an example of a conventional high-frequency switch circuit. The high-frequency switch circuit shown in the figure includes an antenna terminal Ant, a transmission terminal Tx, and a reception terminal Rx. A first switching diode D1 is connected between the transmission terminal Tx and the antenna terminal Ant, and the reception terminal Rx. The strip line SL1 is connected to the antenna terminal Ant, and the second switching diode D2 is connected between the end of the strip line SL1 on the receiving terminal Rx side and the ground potential (for example, (See Patent Document 1).

  The circuit operation when switching transmission / reception of transmission signals and reception signals using the above-described high-frequency switch circuit will be described below.

  First, when transmitting a transmission signal, the control terminal Vc applies a forward bias (the control signal from the control terminal Vc is at a high level) to the first and second switching diodes D1 and D2, and the first and second switching diodes are applied. The diodes D1 and D2 are turned on. At this time, when the first switching diode D1 is turned on, the transmission signal input via the transmission terminal Tx flows to the antenna terminal Ant. On the other hand, when the second switching diode D2 is turned on, the stripline SL1 is grounded via the switching diode D2 and resonates at the communication frequency of the transmission signal. As a result, the impedance of the strip line SL1 becomes maximum, and acts to prevent the transmission signal from entering the reception terminal Rx.

  Further, when receiving the reception signal, the control voltage is not applied to the control terminal Vc (the control signal from the control terminal Vc is low level), and both the first and second switching diodes D1 and D2 are turned off. Accordingly, the reception signal input from the antenna terminal Ant does not flow to the transmission terminal Tx side but flows through the strip line SL1 to the reception terminal Rx side.

As described above, the switching voltages D1 and D2 are controlled to be turned on / off by the control voltage from the control terminal Vc, and the resonance of the strip line SL1 with the ground potential is used to make the transmission signal and the reception signal Transmission / reception is switched.
Japanese Unexamined Patent Publication No. Hei 6-197040

  However, in the conventional high-frequency switch circuit described above, there is some inductance in the second switching diode D2, and the impedance of the stripline SL1 cannot be made infinite at the time of transmission. It was impossible to completely prevent the leak. Therefore, when the transmission signal leaks to the reception terminal Rx side and the signal level is strong, the leakage signal enters the external reception circuit via the reception terminal Rx, thereby causing malfunction of the reception circuit. Had the disadvantages.

  In addition, when the above-described conventional high-frequency switch circuit is used as a front-end module such as a mobile phone, if the leakage signal enters the reception terminal Rx side and such an unnecessary signal is converted into sound, a call is made. It also had the disadvantage of incurring quality degradation.

  The present invention has been devised in view of the above-mentioned drawbacks, and its purpose is to effectively reduce the leakage signal, to correctly operate the receiving circuit, and to be used for a front-end module of a mobile phone. An object of the present invention is to provide a high-frequency switch circuit and a high-frequency switch component that can maintain high quality.

In the high-frequency switch circuit of the present invention, a first switch means including a first switching diode is connected between the antenna terminal connected to the antenna and the transmission terminal connected to the transmission circuit, and the antenna terminal and the reception circuit. A strip line having one end connected to the antenna terminal and the other end connected to the reception terminal, and one end connected to the receiving terminal side end of the strip line and the other end connected to the ground potential. And a second switch means comprising two switching diodes for controlling on / off of the first and second switch means to switch between the connection between the antenna and the transmission circuit and the connection between the antenna and the reception circuit. by the high frequency switching circuit for transmitting and receiving alternately transmit signal and receiving signal, between the receiving terminal and the transmitting terminal, one end Serial connected between the first switching diode and the transmission terminal, and is characterized in that the other end of which is disposed the second anode or capacitor connected to the cathode of the switching diode.

Furthermore, the high-frequency switch circuit of the present invention having the above structure, and is characterized in that it comprises a band-pass filter for cutting off a reception signal between the receiving terminal and the capacitor.

Furthermore, the high-frequency switch component of the present invention, the laminate formed by laminating a plurality of dielectric layers, a high-frequency switch component comprising providing a radio frequency switch circuit of the present invention the above SL either configuration, before Kiko capacitor is characterized in that it is constituted by a pair of electrodes opposing each other via the dielectric layer and the dielectric material layer constituting the laminate.

According to the high frequency switch circuit of the present invention, a capacitor for generating a conversion signal in which the phase of the transmission signal and the level of the transmission signal are changed is connected between the transmission terminal and the reception terminal, and output from the capacitor Since the converted signal is combined with the leakage signal of the transmission signal that leaks between the antenna terminal and the reception terminal on the reception terminal side of the second switch means, the leakage signal and the conversion signal cancel each other, It is possible to reduce the signal level of the leakage signal that enters the external receiving circuit via the receiving terminal. As a result, it is possible to effectively prevent malfunction of the receiving circuit due to the leakage signal and to operate the receiving circuit accurately.

  In addition, when the high-frequency switch circuit of the present invention is used for a front end module of a mobile phone, the signal level of the leaked signal can be reduced to such an extent that the leaked signal is hardly affected when converted into sound. It is possible to improve the call quality of the mobile phone.

Then, according to the high-frequency switch component of the present invention, the switch circuit of the present invention are provided in the laminated body formed by laminating a plurality of dielectric layers, dielectric layer its the capacitor constituting the laminate and dielectric It is configured to include a pair of electrodes facing each other through a layer. Thus, it is possible to simplify the structure of the high-frequency switch component, also compared to the case of constituting the high-frequency switch component and mounting a chip-shaped capacitor on the laminate, the main mounting area of the chip-like element of the stack It is not necessary to secure the surface, and the high-frequency switch component can be miniaturized.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an equivalent circuit diagram showing an embodiment in which the high-frequency switch circuit of the present invention is applied to a high-frequency switch circuit for a DCS (Digital Communication System) communication system (transmission frequency band: 1710 to 1785 MHz, reception frequency band: 1805 to 1880 MHz). The high-frequency switch circuit shown in FIG. 1 schematically includes a first switch means SW1 connected between the antenna terminal Ant and the transmission terminal Tx, and a second switch connected between the antenna terminal Ant and the reception terminal Rx. Means SW2 and a capacitor C5 which is a conversion circuit X connected between the transmission terminal Tx and the reception terminal Rx.

  The first switch means SW1 is composed of a first switching diode D1, its anode is bifurcated, one of which is connected to the transmission terminal Tx via the capacitor C1, and the other is connected to the control terminal Vc via the coil L. The cathode is connected to the antenna terminal Ant via the capacitor C2. Here, the inter-terminal capacitance of the first switching diode D1 is, for example, 0.15 pF, the high-frequency forward resistance is, for example, 1.0Ω, the capacitances of the capacitors C1, C2 are, for example, 33 pF, the inductance of the coil L is, for example, 47 nH, and the resistance R The electrical resistance value is set to 30Ω, for example.

  The switching operation of the first switch means SW1 is controlled by a control signal input via the control terminal Vc. That is, when the control signal becomes high level during transmission, the first switch means is turned on, and the antenna terminal Ant and the transmission terminal Tx are electrically connected. Further, when the control signal becomes a low level at the time of reception, the first switch means is turned off, and the antenna terminal Ant and the transmission terminal Tx are electrically disconnected.

  The resistor R is for limiting the level of the control signal, and the coil L is for preventing high-frequency components such as transmission signals from leaking to the control terminal Vc side.

  On the other hand, the second switch means SW2 is connected between the strip line SL1 connected between the reception terminal Rx and the antenna terminal Ant, and between the end of the strip line SL1 on the reception terminal Rx side and the ground potential GND. The second switching diode D2 is connected to the receiving terminal Rx via the capacitor C3, and the cathode is connected to the ground potential GND via the capacitor C4. The capacitance between the terminals of the second switching diode D2 is set to, for example, 0.15 pF, its high-frequency forward resistance is set to, for example, 1.0Ω, the capacitance of the capacitor C3 is set to, for example, 33 pF, and the capacitance of the capacitor C4 is set to, for example, 6.0 pF. Note that the resonance frequency of the strip line SL1 is determined by the shape of the strip line SL1, the relative dielectric constant, the thickness, etc. of the dielectric layer interposed between the strip line SL1 and the ground electrode.

  The second switch means SW2 is controlled to be in a state opposite to the on / off state of the first switch means SW1 by the control signal described above. That is, when the control signal becomes high level during transmission, the second switch means is turned off, and the antenna terminal Ant and the receiving terminal Rx are electrically disconnected. Further, when the control signal becomes low level during reception, the second switch means is turned on, and the antenna terminal Ant and the reception terminal Rx are electrically connected.

  Thus, when the control signal is at a high level, the first switch means SW1 is turned on and the second switch means SW2 is turned off. When the control signal is at a low level, the first switch means SW1 is turned off, and the second switch means. SW2 is turned on.

Then, one terminal of the capacitor C5 is connected between the transmission terminal Tx and the first switching diode D1, and the other terminal is connected between the second switching diode D2 and the ground potential GND.

Such capacitor C5, serves to transmit signals input through the transmission terminal Tx is input at the same timing, the same strength as propagating to the first switch means SW1, when the capacitor C5 is transmitted, The phase of the transmission signal input to the capacitor C5 is converted, and a converted signal with the signal level attenuated is generated and sent to the connection point B via the second switching diode D2. Therefore, the leakage signal and the conversion signal are synthesized by setting the phase and signal level of the conversion signal so as to cancel the leakage signal of the transmission signal leaking to the receiving terminal Rx side via the second switch means SW2. Thus, the signal level of the leaked signal entering the external receiving circuit can be effectively reduced, and the malfunction of the receiving circuit due to the leaked signal can be effectively suppressed.

  Further, when the high-frequency switch circuit 1 is used as a front-end module of a cellular phone, the signal level of the leakage signal can be reduced to such a degree that the leakage signal is hardly affected when converted into sound. It becomes possible to improve the telephone call quality.

Capacity of such capacitor C5 is determined as follows.

  First, the signal level of the leakage signal in the high frequency switch circuit to which the capacitor C5 is not connected is measured. Next, a capacitor C5 is connected to the high-frequency switch circuit, and the capacitance of the capacitor C5 is changed as a parameter while measuring the signal level of the leakage signal. And the capacity | capacitance of the capacitor | condenser C5 when the signal level of a leakage signal reduces most is determined as an optimal capacity | capacitance of the capacitor | condenser C5 in the high frequency switch circuit of this invention. The capacitor C5 whose capacity has been determined in this way functions as a conversion circuit X that generates a conversion signal that cancels the leakage signal. For example, the capacitance between the terminals of the first and second switching diodes D1 and D2 is 0.15 pF, the high frequency forward resistance is 1.0Ω, the capacitances of the capacitors C1 to C3 are 33 pF, the capacitance of the capacitor C4 is 6.0 pF, When the electric resistance value of the resistor R is 30Ω and the inductance of the coil L is 47 nH, the optimum capacity of the capacitor C5 is determined to be 0.5 pF.

  Next, a circuit operation when the transmission / reception of the transmission signal and the reception signal is switched using the above-described high-frequency switch circuit 1 will be described.

  When transmitting a transmission signal from the transmission terminal Tx to the antenna terminal Ant, a control signal that is a forward bias voltage is supplied from the control terminal Vc to the first and second switching diodes D1 and D2, and the first and second The switching diodes D1 and D2 are turned on. When the first switching diode D1 is turned on, the transmission terminal Tx and the antenna terminal Ant are electrically connected, and the transmission signal input via the transmission terminal Tx is sent to the antenna terminal Ant side.

  At this time, the transmission signal is also input to the conversion circuit X, and a conversion signal generated by shifting the phase of the transmission signal and attenuating to the same level as the leakage signal is generated in the conversion circuit. When this converted signal is sent to the connection point B on the receiving terminal side of the strip line via the second switching diode D2, it is combined with the leakage signal of the transmitting signal leaking to the receiving terminal Rx side, and both signals cancel each other. As a result, the signal level of the leaked signal entering the external receiving circuit is effectively reduced.

  As described above, the mechanism for generating the leakage signal is that there is a slight inductance in the second switching diode D2, and the impedance of the stripline SL1 cannot be made infinite during transmission.

  On the other hand, when a reception signal received at the antenna terminal Ant is sent to the reception circuit via the reception terminal Rx, a control signal (voltage) that turns off the switching diodes D1 and D2 to the first and second switching diodes D1 and D2. Is also supplied via the control terminal Vc, and the first and second switching diodes D1 and D2 are turned off. When the second switching diode is turned off, the strip line SL1 acts as a simple transmission line, the antenna terminal Ant and the reception terminal Rx are electrically connected, and the reception signal input via the antenna terminal Ant is received. It is sent out to the terminal Rx side. Further, when the first switching diode D1 is turned off, the antenna terminal Ant and the transmission terminal Tx are electrically disconnected, and the reception signal does not flow to the transmission terminal Tx side. At this time, since one terminal of the capacitor C5 is connected to the cathode side of the second switching diode D2, the reception signal does not leak to the transmission terminal Tx side via the capacitor C5.

Thus, in the high-frequency switch circuit 1 of the present embodiment described above, the strip line SL1 is short-circuited to the ground potential GND while the first and second switching diodes D1 and D2 are switched on and off at high speed by an external control signal. It serves as a high frequency switch circuit by switching the transmission and reception of the transmitted and received signals by utilizing the resonance of the case.

  Next, a high-frequency switch component provided with the above-described high-frequency switch circuit inside the laminate will be described with reference to FIGS.

  2 is an external perspective view of a high-frequency switch component according to an embodiment of the present invention, and FIGS. 3B to 3F are top views of each layer of the high-frequency switch component shown in FIG. In the high-frequency switch component shown in the figure, the chip component 8 is mounted on the upper surface of the laminate 2 composed of a plurality of dielectric layers 20a to 20f, and internal electrode layers such as the transmission line 21 and the capacitor electrode 22 are formed therein. is doing. Various terminal electrodes are formed on the lower surface of the laminate 2 as shown in FIG. FIG. 3A is a top view when the chip component 8 is mounted on the dielectric layer 20a.

The laminate 2 is formed by laminating a plurality of dielectric layers 20a to 20f, and each dielectric layer is formed of a dielectric ceramic material, a sintering agent, a low melting point glass material, or the like. As such a dielectric ceramic material, for example, a ceramic material such as BaO—TiO ₂ , Ca—TiO ₂ , or MgO—TiO ₂ is used, and the thickness of each dielectric layer is about 50 to 300 μm per layer. Is set to

  A pair of lands 9 corresponding to the terminals of each chip component 8 are formed on the upper surface of the laminated body 2 in a deposited manner. The chip component 8 is attached to the land 9 by joining the terminals of the chip component 8 via a conductive adhesive. In the present embodiment, as the chip component 8, a PIN diode that forms the first and second switching diodes D1 and D2, a chip resistor that forms the resistor R, a chip inductor that forms the coil L, and capacitors C1 to C3 are formed. A chip capacitor is used.

  In addition, a capacitor electrode 22 and a transmission line 21 are formed inside the laminate 2.

  The transmission line 21 is formed on the upper surface of the dielectric layer 20c so as to form a predetermined strip pattern, thereby forming a strip line SL1.

Capacitor Also the capacitor electrode 22, the dielectric layer 20d, are formed on the upper surface of 20e, which functions as a conversion circuit X by opposed with the dielectric layer 20d between the capacitor electrode 22 to each other C5 is formed.

High-frequency switch component described above, capacitor C5 is a pair of capacitor electrodes 22 which face each other via, for example, dielectric layer 20d and the dielectric layer 20d of the respective dielectric layers 20 a ~20f constituting the laminate 2 Therefore, the overall structure of the high-frequency switch component can be simplified, and there is an advantage that the high-frequency switch component can be miniaturized as compared with the case where it is formed of a chip component.

  The capacitor electrode 22 and the transmission line 23 formed inside the laminate 2 are made of a conductive material mainly composed of an Ag alloy such as Ag, Ag-Pd, Ag-Pt, and the thickness thereof is, for example, It is set to 5 to 25 μm.

  Further, as shown in FIG. 3 (h), an antenna terminal electrode 3, a transmission terminal electrode 4, a reception terminal electrode 5, a control terminal electrode 6, and a ground terminal electrode 7 are formed on the lower surface of the multilayer body 2. These terminal electrodes are made of a conductive material mainly composed of an Ag alloy such as Ag, Ag-Pd, Ag-Pt, etc., and the thickness thereof is set to, for example, 5 to 25 μm, similarly to the conductor layer formed inside the laminate. Is done.

  The above-described various chip components, internal electrode layers, and terminal electrodes are electrically connected by via holes or the like formed in the dielectric layer, so that a high frequency switch circuit 1 as shown in FIG. 1 is manufactured.

Experimental example

  Next, the operational effects of the present invention described above will be described with reference to FIG.

FIG. 6A is a graph showing the result of measuring the transmission loss characteristic of a transmission signal using a conventional high-frequency switch circuit 1 as a comparative example, and FIG. 6B is a transmission using the high-frequency switch circuit of the present invention. It is a graph which shows the result of having measured the passage loss characteristic of a signal.

Each of the experimental samples used for the above-described measurement is the same as the high-frequency switch circuit 1, the first and second switching diodes D1 and D2 having a capacitance between terminals of 0.15 pF and a forward resistance of 1.0Ω. 33 pF capacitors C1 to C3, a capacitor C4 having a capacitance of 6.0 pF, a transmission line having a width of 0.1 mm and a length of 6.0 mm, and the dielectric constant of the dielectric layer interposed between the ground electrode The strip line SL1 having a rate εr of 18.7, a resistor R having an electric resistance value of 30Ω, and a coil L having an inductance of 47 nH, and the transmission frequency band is set to a range of 1710 to 1785 MHz. Then, in the present invention products used for the measurement of FIG. 6 (b), further have use a capacitor C5 having a capacitance 0.5 pF, the converted signal obtained by shifting only the phase 185.7 ° with respect to the leakage signal phase It was configured to generate.

  According to FIG. 6, in the conventional product shown in (a), the pass loss characteristic in the vicinity of the transmission frequency band (1710 to 1785 MHz) is poor and the measured value is about −25 dB, whereas in FIG. In the invention, the pass loss characteristic in the vicinity of the transmission frequency band (1710 to 1785 MHz) is greatly improved to -30 dB or less, and it can be seen that the isolation is improved. This is because a leaked signal in which both signals cancel each other out and enters an external receiving circuit via the receiving terminal Rx by synthesizing the converted signal shifted in phase by 185.7 ° with respect to the phase of the leaked signal. This is because the signal level is greatly reduced.

  From these results, the product of the present invention is superior to the conventional product in order to significantly reduce the signal level of the leaked signal entering the receiving circuit and effectively prevent malfunction of the receiving circuit caused by the leaked signal. I understand that.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the high-frequency switch circuit is configured so that the control terminal Vc is connected to the connection point between the first switching diode D1 and the capacitor C1 via the resistor R. As shown in FIG. 2, a control terminal Vc may be connected via a resistor R between the second switching diode D2 and the capacitor C4 to constitute a high frequency switch circuit.

In the above-described embodiment, one end of the capacitor C5 is connected to the cathode side of the second switching diode D2, so that a reception signal does not flow to the transmission terminal Tx via the capacitor C5 during reception. Instead, a band-pass filter BPF that passes only the frequency band of the transmission signal is connected between the reception terminal Rx and the capacitor C5 so that the reception signal does not flow to the transmission terminal Tx side during reception. May be. As such a bandpass filter BPF, for example, as shown in the equivalent circuit diagram of FIG. 5, a filter in which two LC resonance circuits are connected in parallel is preferably used.

  Furthermore, in the above-described embodiment, the high-frequency switch circuit of the present invention has been described as an example of a circuit used in a DCS communication system communication device. However, other time division connection communication systems such as GSM (Global System for Mobile) It goes without saying that the present invention may be applied as a circuit used in communication equipment of a communication system or a PCS (Personal Communication System) communication system.

It is an equivalent circuit diagram of the high frequency switch circuit concerning one embodiment of the present invention. 1 is an external perspective view of a high-frequency switch component according to an embodiment of the present invention. (A) is a top view of the high-frequency switch component of FIG. 2, and (b) to (g) are top views of each layer of the high-frequency switch component of FIG. 2, and (f) is a bottom view of the high-frequency switch component of FIG. FIG. 5 is an equivalent circuit diagram of a high frequency switch circuit according to another embodiment of the present invention. FIG. 5 is an equivalent circuit diagram of a high frequency switch circuit according to another embodiment of the present invention. (A) is a graph showing the result of measuring the transmission loss characteristic of a transmission signal using the conventional high-frequency switch circuit 1, and (b) is the measurement of the transmission loss characteristic of the transmission signal using the high-frequency switch circuit of the present invention. It is a graph which shows the result. It is an equivalent circuit diagram which shows an example of the conventional high frequency switch circuit.

Explanation of symbols

Tx: Transmission terminal Rx: Reception terminal Ant: Antenna terminal SW1: First switch means SW2: Second switch means X: Conversion circuit
C5: Capacitor Vc ... Control terminal D1 ... First switching diode D2 ... Second switching diode SL ... Strip line R ... Resistance L ... Coil BPF ... Band Pass filter 1 ... high frequency switch circuit 2 ... laminate 3 ... antenna terminal electrode 4 ... transmission terminal electrode 5 ... reception terminal electrode 6 ... control terminal electrode 7 ... ground terminal electrode 8 ... chip component 9 ... land 20 a ~20f ··· dielectric layer 21 ... transmission line 22 ... capacitor electrode

Claims (3)

First switch means comprising a first switching diode between an antenna terminal connected to the antenna and a transmission terminal connected to the transmission circuit, one end between the antenna terminal and the reception terminal connected to the reception circuit. Is connected to the antenna terminal and the other end is connected to the receiving terminal, and the second end of the strip line is connected to the receiving terminal side end and one end and the other end is connected to the ground potential . Switch means,
In a high-frequency switch circuit that controls on / off of the first and second switch means and alternately transmits and receives a transmission signal and a reception signal by switching a connection between an antenna and a transmission circuit and a connection between an antenna and a reception circuit ,
A capacitor having one end connected between the first switching diode and the transmission terminal and the other end connected to an anode or a cathode of the second switching diode between the transmission terminal and the reception terminal. A high-frequency switch circuit characterized by being arranged . Between the receiving terminal and the capacitor, high-frequency switch circuit according to claim 1, characterized in that it comprises a band-pass filter for cutting off a reception signal. A high-frequency switch component comprising the high-frequency switch circuit according to claim 1 or 2 provided in a laminate formed by laminating a plurality of dielectric layers,
Before Kiko capacitor is, the high-frequency switch component, characterized in that it is constituted by a pair of electrodes opposing each other via the dielectric layer and the dielectric material layer constituting the laminate.

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