JP2008236017A - High frequency circuit, high frequency circuit component, and communication apparatus employing them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency circuit which can be shared with at least two communication systems and suitable when a low noise amplifier circuit is shared, and to provide a high frequency component and a communication apparatus employing it. <P>SOLUTION: A high frequency circuit having a common terminal to which reception signals of first and second frequency bands are inputted, a first reception terminal to which the reception signal of first frequency band is delivered, a second reception terminal to which the reception signal of second frequency band is delivered, and a low noise amplifier circuit for amplifying the reception signals of first and second frequency bands is further provided with a variable notch filter circuit connected between the common terminal and the low noise amplifier circuit and passing the signal of first frequency band when a signal of first frequency band is received but blocking the signal of the first frequency band when a signal of the second frequency band is received, and a circuit connected between the first and second reception terminals and demultiplexing the signals of the first and second frequency bands. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus that performs wireless transmission between electronic and electrical devices, and more particularly to a high-frequency circuit that can be shared by at least two communication systems and a communication apparatus using the same.

  At present, data communication using a wireless LAN represented by the IEEE 802.11 standard is widely used. For example, personal computers (PCs), PC peripherals such as printers, hard disks, broadband routers, fax machines, refrigerators, standard televisions (SDTVs), high-definition televisions (HDTVs), electronic devices such as cameras, videos, and mobile phones, automobiles It is adopted as a signal transmission means that replaces wired communication in an airplane or in an aircraft, and wireless data transmission is performed between the respective electronic and electrical devices.

  As a wireless LAN standard, IEEE802.11a supports high-speed data communication of a maximum of 54 Mbps using an OFDM (Orthogonal Frequency Division Division) modulation method, and a frequency band of 5 GHz is used. IEEE802.11b is a DSSS (Direct Sequence Spread Spectrum) system that supports high-speed communication at 5.5 Mbps and 11 Mbps, and is a 2.4 GHz ISM (industrial) that can be used freely without a radio license. , Science and medical) bands. Further, IEEE802.11g supports high-speed data communication of a maximum of 54 Mbps using the OFDM modulation scheme, and uses the 2.4 GHz band as in the case of IEEE802.11b.

  The inventor has already provided a communication device, a high-frequency circuit, and a high-frequency circuit component using such a wireless LAN (for example, Patent Document 1). As shown in FIG. 6, the high-frequency circuit includes a high-frequency switch circuit 1, a first branching circuit 3, a second branching circuit 2, a low-pass filter circuit 5, a low-pass filter circuit 6, and a first high-frequency power amplifier 8. , A second high-frequency power amplifier 9, a first low-noise amplifier 17, a second low-noise amplifier 7, and a detection circuit 16, and a harmonic such as a low-pass filter between the multiband antenna terminal and the high-frequency switch circuit 1. A reduction circuit is provided. In a communication device using a wireless LAN, the mounting space for the high-frequency components that form the communication device is limited. Therefore, the high-frequency components and the high-frequency circuits used in the communication devices may be small in addition to high performance. Required. On the other hand, the configuration of Patent Document 1 enables reduction of harmonic signals generated by the detection diode and reduction of harmonic signals generated by the low noise amplifier.

JP 2006-304081 A

  However, the configuration described in Patent Document 1 cannot be said to sufficiently satisfy the demand for circuit miniaturization. For example, the high-frequency circuit described in Patent Document 1 requires the first low-noise amplifier 17 and the second low-noise amplifier 7 in the 2.4 GHz band and 5 GHz band reception side paths, respectively. From the viewpoint of cost reduction and miniaturization of high-frequency circuits and high-frequency components, it is desirable to reduce the number of low-noise amplifiers that are constituent elements. On the other hand, it is effective to arrange a broadband low-noise amplifier in front of the branching circuit. However, if a single low-noise amplifier is used to amplify a plurality of received signals in different frequency bands, signals with different frequency bands enter the low-noise amplifier and easily interfere with each other to generate signal distortion. There was a problem that.

  In view of such problems, the present invention provides a configuration suitable for sharing a low-noise amplifier circuit in a high-frequency circuit that can be shared by at least two communication systems, a small and high-performance high-frequency circuit, An object is to provide a high-frequency circuit component and a communication device used.

  The present invention includes a common terminal (Tcom) to which received signals in the first and second frequency bands are input, a first receiving terminal (Rx_a) from which the received signals in the first frequency band are output, A second reception terminal (Rx_b) from which a reception signal in the second frequency band is output; and a low noise amplification circuit (LNA) for amplifying the reception signals in the first and second frequency bands, A variable notch filter circuit (VNF) that passes the signal of the first frequency band when receiving a signal of the first frequency band and blocks the signal of the first frequency band when receiving the signal of the second frequency band. ) Is connected between the common terminal (Tcom) and the low noise amplifier circuit (LNA), and the low noise amplifier circuit (LNA), the first reception terminal (Rx_a), and the second reception terminal ( Rx_b) between the first and second frequencies A high-frequency circuit (20) including a demultiplexing circuit (Dip2) for demultiplexing a band signal. By sharing a low noise amplifier circuit (LNA) for amplification of received signals in different frequency bands, the high frequency circuit can be simplified and miniaturized. Furthermore, according to the above configuration, it is possible to prevent signals having different frequency bands from entering the low noise amplifier (LNA) and interfering with each other to generate signal distortion.

  In the high-frequency circuit (20), an antenna terminal (Ant) to which transmission / reception signals are inputted / outputted, a transmission terminal (Tx_a, Tx_b) to which the antenna terminals (Ant) and transmission signals are inputted, or reception to which reception signals are outputted. A high-frequency switch circuit (SW) having at least three ports that switches connection with the terminals (Rx_a, Rx_b) is provided, and a port on the receiving terminal side of the high-frequency switch circuit (SW) is connected to the common terminal (Tcom). It is preferable to be connected.

  In the high frequency circuit (20), the variable notch filter circuit (VNF) applies a voltage to the inductor (L), the capacitor (C), the resistor (R), the switch circuit (D), and the switch circuit (D). It is preferable to have a voltage terminal.

  In the high-frequency circuit (20), the switch circuit (D) is preferably a PIN diode.

  In the high-frequency circuit (20), the switch circuit (D) is preferably an FET (field effect transistor).

  In the present invention, at least a part of the variable notch filter circuit (VNF), the high frequency switch circuit (SW), and the low noise amplifier circuit (LNA) in the high frequency circuit (20) is mounted on the laminate (10). The remainder is a high-frequency circuit component (30) configured in the laminate (10) with an electrode pattern.

  Furthermore, the present invention is a communication device using the high frequency circuit (20) or the high frequency circuit component (30).

  According to the present invention, in a high-frequency circuit that can be shared by at least two communication systems, a configuration suitable for sharing a low-noise amplifier circuit is provided, a small and high-performance high-frequency circuit, and a high-frequency circuit using the same Components and communication devices can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. FIG. 1 shows an example of the present invention that can share two communication systems of 2.4 GHz band wireless LAN (IEEE802.11b and / or IEEE802.11g) and 5 GHz band wireless LAN (IEEE802.11a and / or IEEE802.11h). The circuit block of an embodiment is shown. The high-frequency circuit according to the present invention includes a common terminal (Tcom) to which received signals in the first and second frequency bands are input, and a first receiving terminal (Rx_a) from which the received signals in the first frequency band are output. ), A second reception terminal (Rx_b) from which a reception signal in the second frequency band is output, and a low noise amplification circuit (LNA) that amplifies the reception signals in the first and second frequency bands Have. The low noise amplifier circuit is also called a low noise amplifier circuit. The first frequency band will be described below as a 2.4 GHz band wireless LAN, and the second frequency band will be described as a 5 GHz band wireless LAN having a higher frequency. Furthermore, the high-frequency circuit according to the present invention passes the signal of the first frequency band when receiving the signal of the first frequency band, and passes the signal of the first frequency band when receiving the signal of the second frequency band. A variable notch filter circuit (VNF) for blocking is connected between the common terminal (Tcom) and the low noise amplifier circuit (LNA), and the low noise amplifier circuit (LNA), the first reception terminal (Rx_a), and the second A demultiplexing circuit (Dip2) for demultiplexing signals in the first and second frequency bands is provided between the receiving terminal (Rx_b).

  In the present invention, a variable notch filter circuit (VNF) that can adjust the position of the attenuation pole by an external control input is used. By using the variable notch filter circuit (VNF), when the 2.4 GHz band signal as the first frequency band is received, the signal in the first frequency band is passed and the 5 GHz band as the second frequency band is passed. When receiving the signal, the 2.4 GHz band signal which is the first frequency band is blocked. That is, in the high-frequency circuit according to the present invention, the variable notch filter circuit (VNF) is used to block signals of some communication systems among two or more communication systems to be used. This point is different from the conventional usage mode for simply reducing unnecessary harmonics. Further, the variable notch filter circuit (VNF) is provided in front of the low noise amplifier circuit (LNA), and is subsequent to the low noise amplifier circuit (LNA), that is, the low noise amplifier circuit (LNA) and the first receiving terminal (Rx_a). ) And the second receiving terminal (Rx_b), a demultiplexing circuit (Dip2) for demultiplexing the first and second frequency bands is provided. According to such a configuration in which the low noise amplifier circuit (LNA) is shared between the 2.4 GHz band and the 5 GHz, the high frequency circuit can be downsized. In such a case, by using the variable notch filter circuit (VNF) having the above-described configuration, it is possible to prevent signals having different frequency bands from entering the low noise amplifier (LNA) and interfering with each other to generate signal distortion. Can do.

  The above-described configuration according to the present invention may be applied to a high-frequency circuit mainly including a reception path such as that used in a reception module, or may be applied to a high-frequency circuit that includes a transmission path and is used for transmission / reception. The high-frequency circuit of the circuit block shown in FIG. 1 is a transmission / reception high-frequency circuit used in a dual-band wireless device that performs wireless communication selectively using the first and second frequency bands. In the configuration of FIG. 1, an antenna terminal (Ant) that is connected to a multiband antenna and receives transmission / reception signals, and an antenna terminal (Ant) and a transmission terminal that receives transmission signals or a reception terminal that outputs reception signals. A high-frequency switch circuit (SW) having at least three ports for switching the connection to is provided. The port on the receiving terminal side of the high frequency switch circuit (SW) is connected to the common terminal (Tcom), and the first branching circuit (Dip1) is connected to the port on the transmission terminal side of the high frequency switch circuit (SW). . The high-frequency switch circuit (SW) can be composed of an FET (field effect transistor) or a PIN diode. The first demultiplexing circuit (Dip1) is composed of a low-frequency filter circuit and a high-frequency filter circuit. The low-frequency filter circuit passes a 2.4 GHz band wireless LAN transmission signal and transmits a 5 GHz band wireless LAN. Attenuate the signal. On the other hand, the high frequency side filter circuit passes the transmission signal of the 5 GHz band wireless LAN and attenuates the transmission signal of the 2.4 GHz band wireless LAN.

  The circuit configuration between the high frequency switch circuit (SW) and the transmission terminal is not particularly limited. In the configuration of FIG. 1, the first power amplifier circuit (PA1) is connected to the low frequency filter circuit of the first branching circuit (Dip1), and the first power amplifier circuit (PA1) is the first power amplifier circuit (PA1). It is connected to a transmission terminal (Tx_b) of the 2.4 GHz band wireless LAN through a band pass filter circuit (BPF1). Here, the bandpass filter circuit (BPF1) removes unnecessary noise outside the band included in the transmission signal. The first power amplifier circuit (PA1) amplifies a transmission signal input from a 2.4 GHz band wireless LAN transmission side circuit. The low frequency side filter circuit of the first branching circuit (Dip1) has an effect of attenuating the harmonic signal generated in the first power amplifier circuit (PA1).

  A second power amplifier circuit (PA2) is connected to the high frequency side filter circuit of the first branching circuit (Dip1) through a low pass filter (LPF). Further, the second power amplifier circuit (PA2) is connected to the transmission terminal (Tx_a) of the 5 GHz band wireless LAN via the second bandpass filter circuit (BPF2).

  Here, the band pass filter circuit (BPF2) removes unnecessary noise outside the band included in the transmission signal, and the second power amplifier circuit (PA2) is input from the transmission side circuit of the 5 GHz band wireless LAN. Amplifies the transmission signal. The low-pass filter (LPF) allows the amplified transmission signal to pass therethrough but has an effect of attenuating the harmonic signal generated by the second power amplifier circuit (PA2). Note that circuit elements such as a filter can be added to or deleted from the configuration shown in FIG. 1 according to required characteristics. For example, a detection circuit may be provided between the high frequency switch circuit (SW) and the first branching circuit (Dip1). This detection circuit can be provided between the first demultiplexing circuit (Dip1) and each of the power amplification circuits (PA1, PA2). In this case, however, two detection circuits are required, and the size of the detection circuit is small. It is not suitable for conversion. Also, a detection output can be provided in each power amplifier circuit (PA1, PA2). In this detection circuit, high-frequency power is detected by a detection diode based on the transmission signal detected by the coupler, and this detection signal is fed back via an RFIC circuit and used for controlling each power amplifier circuit (PA1, PA2). Is done.

  Next, the reception path side of the high frequency circuit will be described. A port on the receiving terminal side of the high-frequency switch circuit (SW) having at least three ports is connected to a common terminal (Tcom). For example, an SPDT (single pole double throw) switch can be used as the high frequency switch circuit (SW). A variable notch that passes a signal in the first frequency band when receiving a signal in the first frequency band and blocks a signal in the first frequency band when receiving a signal in the second frequency band at the common terminal (Tcom). A filter circuit (VNF) is connected. A low noise amplifier circuit (LNA) that amplifies the received signals in the first and second frequency bands is connected to the subsequent stage of the variable notch filter circuit (VNF). Further, a demultiplexing circuit (Dip2) for demultiplexing the first and second frequency bands between the low noise amplifier circuit (LNA) and the first receiving terminal (Rx_a) and the second receiving terminal (Rx_b). Is provided. In other words, the above configuration is a configuration in which received signals in different frequency bands are amplified by one low noise amplifier circuit, and a branch of a path for each frequency is performed at a subsequent stage of the low noise amplifier circuit. This low noise amplifier circuit (LNA) amplifies the reception signal of the 2.4 GHz band wireless LAN and the reception signal of the 5 GHz band wireless LAN. In this case, it is desirable to use low noise amplification that has a flat gain frequency characteristic and covers a wide band so as to amplify the reception signals of the 2.4 GHz band and 5 GHz band wireless LAN. According to such a configuration, received signals in different frequency bands can be amplified by one low noise amplifier circuit, so that the high frequency circuit can be simplified and miniaturized. In addition, this circuit configuration can reduce the size and cost of high-frequency circuit components, and further eliminates the need to use a demultiplexing circuit and a bandpass circuit on the input side of the low-noise amplifier circuit. There are effects such as improvement.

  In the subsequent stage of the demultiplexing circuit (Dip2), a first reception terminal (Rx_a) from which a reception signal in the first frequency band is output, and a second reception terminal (in which the reception signal in the second frequency band is output) Rx_b) is provided. The second demultiplexing circuit (Dip2) is composed of a low frequency side filter circuit and a high frequency side filter circuit, and the low frequency side filter circuit passes the reception signal of the 2.4 GHz band wireless LAN and receives the reception of the 5 GHz band wireless LAN. Attenuate the signal. On the other hand, the high frequency side filter circuit passes the reception signal of the 5 GHz band wireless LAN and attenuates the reception signal of the 2.4 GHz band wireless LAN. The signal amplified by low noise amplification by this action is demultiplexed by the second demultiplexing circuit (Dip2), and the reception signal of the 2.4 GHz band wireless LAN is routed through the third bandpass filter circuit (BPF3). The signal is output to the reception end (Rx_b) of the 2.4 GHz band wireless LAN, and the reception signal of the 5 GHz band wireless LAN is output to the reception end (Rx_a) of the 5 GHz band wireless LAN.

  The operation of the variable notch filter (VNF) inserted between the high frequency switch circuit (SW) and the low noise amplifier circuit (LNA) in FIG. 1 will be described with reference to FIG. In FIG. 2, the variable notch filter (VNF) inserted between the high-frequency switch circuit (SW) and the low-noise amplifier circuit (LNA) is the first when receiving the first frequency band (f1 = 2.4 GHz). The first frequency band (f1 = 2.4 GHz) is blocked when receiving the second frequency band (f2 = 5 GHz) (FIG. 2 (b)).

  FIG. 3 is an example of a variable notch filter (VNF). The variable notch filter circuit (VNF) has an inductor (L), a capacitor (C), a resistor (R), a switch circuit (D), and a voltage terminal (VC) for applying a voltage to the switch circuit. The switch circuit (D) can be composed of an FET (field effect transistor) or a PIN diode. The use of an FET has the advantage that the drive current can be reduced and the switching speed can be increased, and the use of a PIN diode has the advantage that a small package product can be used at a low price. In the configuration of FIG. 3, one end of a capacitor (C) is connected to the node of the path of the received signal, and one end of an inductor (L) is connected in series to the other end of the capacitor (C). One end of a switch circuit (D) is further connected in series to the other end of the inductor (L), and the other end of the switch circuit is grounded. One end of a resistor (R) is connected to a node between the other end of the inductor (L) and one end of the switch circuit (D), and the other end of the resistor R is connected to a voltage terminal (VC). The attenuation pole of the notch filter circuit can be adjusted by ON / OFF control of the diode (D), which is a switch circuit, using the bias voltage from the voltage terminal (VC). Here, it is preferable to select a diode (D) having a small OFF-time capacitance of about 0.3 to 0.5 pF, such as a PIN diode. The diode (D) functions as a minute inductor of about 0.1 nH when ON. That is, in FIG. 3, for example, the capacitor (C) is set to a circuit constant of about 2 pF, the inductor (L) is set to about 1 nH, and the diode (D) is ON / OFF controlled to change the resonance frequency of the LC resonance. The S parameter S21 indicating the transmission characteristic indicates a characteristic as shown in FIG. 4, for example. When the diode (D) is ON, the center frequency of the attenuation pole is f1 (= 2.4 GHz), and when the diode (D) is OFF, the center frequency of the attenuation pole is f2, which is different from f1. Accordingly, when receiving the first frequency band (2.4 GHz), the variable notch filter (VNF) turns off the diode (D) and passes the first frequency band. On the other hand, when receiving the second frequency band (f2 = 5 GHz), the diode (D) is turned on to attenuate and block the first frequency band (f1 = 2.4 GHz). Thus, by setting the center frequency of the first frequency band to 2.4 GHz and the center frequency of the second frequency band to 5 GHz, a high-frequency circuit suitable for a dual-band wireless LAN using the frequency band is provided. Can do. Although the center frequency of the attenuation pole is not necessarily f2 (5 GHz) when the diode (D) is OFF, an unnecessary signal having the frequency f2 flows into the low-noise amplifier circuit by using this configuration. It is possible to prevent the signal in the first frequency band f1 from being distorted.

  The case where the center frequency f1 = 2.4 GHz as the first frequency band and the center frequency f2 = 5 GHz as the second frequency band has been described above. However, the present invention is not limited to this, and any frequency can be used. Applicable to any combination. Moreover, it is applicable not only to multiband but also to multiband communication of triple band or higher. The stop band of the variable notch filter circuit (VNF) is not limited to the 2.4 GHz band. As the first frequency band and / or the second frequency band, a band of 2.6 GHz or 3.5 GHz used for WiMAX may be used.

  Next, an embodiment in which a high-frequency circuit component having a high-frequency circuit according to one embodiment of the present invention is configured as a multilayer component (component using a ceramic multilayer substrate) will be described. In the high-frequency circuit component according to the present invention, at least a part of the variable notch filter circuit, the high-frequency switch circuit, and the low-noise amplifier circuit in the high-frequency circuit is mounted on the stacked body, and the remaining part is configured in the stacked body by an electrode pattern. .

  FIG. 5 is a perspective view of an embodiment of the high-frequency circuit component according to the present invention, in which the mounting component is mounted on the laminate (10). A variable notch filter circuit (VNF), a high frequency switch circuit (SW), a low noise amplifier circuit (LNA), and a power amplifier circuit (PA) are mounted on the laminate (10). As shown in FIG. 3, the variable notch filter circuit (VNF) includes a capacitor (C), an inductor (L), a resistor (R), and a diode (D). In FIG. 5, these are all mounted on the laminate (10) as chip parts.

  The laminate (10) is made of, for example, a ceramic dielectric material LTCC (Low Temperature Co-fired Ceramics) that can be sintered at a low temperature of 1000 ° C. or less, and is formed of a low resistivity Ag on a green sheet having a thickness of 10 μm to 200 μm. It can be manufactured by printing a conductive paste such as Cu or Cu to form a predetermined electrode pattern, appropriately laminating a plurality of green sheets, and sintering. As the dielectric material, for example, Al, Si, Sr as a main component, Ti, Bi, Cu, Mn, Na, K as a subcomponent, Al, Si, Sr as a main component, Ca, Pb, A material containing Na and K as a multicomponent, a material containing Al, Mg, Si, and Gd, and a material containing Al, Si, Zr, and Mg are used, and a material having a dielectric constant of about 5 to 15 is used.

In addition to the ceramic dielectric material, it is also possible to use a resin multilayer substrate or a multilayer substrate made of a composite material obtained by mixing a resin and ceramic dielectric powder. Further, the ceramic substrate is made of HTCC (high temperature co-fired ceramic) technology, the dielectric material is mainly Al ₂ O ₃ , and the transmission line and the like can be sintered at a high temperature such as tungsten or molybdenum. You may comprise as a conductor.

  The laminated body (10) includes a variable notch filter (VNF), a high frequency switch circuit (SW), a low noise amplifier circuit (LNA), and a power amplifier circuit (PA) mounted on the laminated body (10) in FIG. Other than the above, the low pass filter (LPF) and the band pass filter (BPF) shown in FIG. 1 are formed. By forming such a circuit element in the laminated body (10), a small high-frequency component in which the high-frequency switch circuit (SW) and the power amplifier circuit (PA) are integrated can be realized.

  The ceramic laminated substrate of this example had a planar dimension of 6.5 mm × 5.3 mm, and could be configured very small. Moreover, the height of the ceramic laminated substrate was as thin as 0.6 mm, and by mounting the semiconductor element by bare chip, it was possible to configure the height to 1.3 mm including the mounted components and the resin sealing thereof. That is, it was possible to reduce the size to 7 mm square or less with this planar size.

  In the conventional circuit configuration, a signal of −15 dBm in the 2.4 GHz band is input to the low noise amplifier, and a harmonic generation amount of 5 GHz, which is twice this frequency, is output from the reception terminal in the 5 GHz band by −30 dBm and received in the 5 GHz band. The sensitivity to the signal was degraded. On the other hand, by applying the present invention using VNF, it is possible to reduce the amount of harmonics output from the receiving terminal in the 5 GHz band to -70 dBm, thereby preventing deterioration of the receiving sensitivity. Things became possible.

  For example, a 2.4 GHz band wireless LAN (IEEE802.11b and / or IEEE802.11g) and a 5 GHz band wireless LAN (IEEE802.11a and / or Alternatively, an RF front-end circuit that can share two IEEE802.11h communication systems is provided, and a small multiband communication device using the RF front-end circuit can be realized. The communication system is not limited to the frequency band and communication standard described above, and can be used for various communication systems. In addition to the two communication systems, for example, by adopting a configuration in which the high-frequency switch circuit is switched in more stages, it is possible to cope with a larger number of communication systems. As a communication apparatus using the high-frequency circuit or high-frequency circuit component according to the present invention, for example, a wireless communication device represented by a mobile phone, a personal computer (PC), a peripheral device of a PC such as a printer, a hard disk, a broadband router, a FAX, It can be deployed in refrigerators, standard television (SDTV), high-definition television (HDTV), cameras, video, and other home electronic devices.

It is a circuit block of the high frequency circuit concerning one example of the present invention. It is a figure which shows the function of the variable notch filter used for the high frequency circuit of this invention. It is a circuit diagram of the variable notch filter used for the high frequency circuit of this invention. It is S21-frequency characteristic figure of the high frequency circuit of this invention. It is a perspective view of the high frequency circuit component of this invention. It is a circuit block diagram which shows an example of the conventional high frequency circuit.

Explanation of symbols

Ant: Antenna terminals Rx_a, Rx_b: Reception terminals Tx_a, Tx_b: Transmission terminal Tcom: Common terminal VNF: Variable notch filter circuit LNA: Low noise amplification circuit Dip1, Dip2: Demultiplexing circuit SW: High frequency switch circuit f1: First frequency Center frequency f2 of band: Center frequency of second frequency band 10: Laminate 20: High frequency circuit 30: High frequency circuit component

Claims (7)

A common terminal to which received signals in the first and second frequency bands are input;
A first reception terminal from which a reception signal of the first frequency band is output;
A second reception terminal from which a reception signal of the second frequency band is output;
A low-noise amplifier circuit for amplifying the received signals in the first and second frequency bands,
A variable notch filter circuit that passes the signal of the first frequency band when receiving the signal of the first frequency band and blocks the signal of the first frequency band when receiving the signal of the second frequency band; Connected between the common terminal and the low-noise amplifier circuit;
A demultiplexing circuit for demultiplexing the signals of the first and second frequency bands is provided between the low noise amplifier circuit and the first receiving terminal and the second receiving terminal. High frequency circuit. An antenna terminal for transmitting / receiving signals;
A high-frequency switch circuit having at least three ports for switching the connection between the antenna terminal and a transmission terminal to which a transmission signal is input or a reception terminal to which a reception signal is output;
The high frequency circuit according to claim 1, wherein a port on the receiving terminal side of the high frequency switch circuit is connected to the common terminal.   The high frequency circuit according to claim 1, wherein the variable notch filter circuit includes an inductor, a capacitor, a resistor, a switch circuit, and a voltage terminal that applies a voltage to the switch circuit.   The high-frequency circuit according to claim 1, wherein the switch circuit is a PIN diode.   The high-frequency circuit according to any one of claims 1 to 3, wherein the switch circuit is an FET. At least a part of the variable notch filter circuit, the high-frequency switch circuit, and the low-noise amplifier circuit in the high-frequency circuit according to any one of claims 1 to 5 is mounted on a laminate,
A high-frequency circuit component, wherein the remaining portion is configured in the laminated body by an electrode pattern. A communication device using the high-frequency circuit according to claim 1 or the high-frequency circuit component according to claim 6.