JP2008219699A - Low-noise amplifier circuit, high-frequency circuit, high-frequency component, and communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-noise amplifier circuit suitable for use of a wide band by flattening gain characteristics of a low-noise amplifier circuit used to amplify a signal in a radio communication device etc., and a high-frequency circuit, a high-frequency component, and a communication device using the same. <P>SOLUTION: The low-noise amplifier circuit has a transistor 1, an input path connected to the base of the transistor 1, and an output path connected to the collector of the transistor 1, and includes a feedback circuit connecting a node 2 of the output path and a node 3 of the input path through a resistance RL2, a capacitor CL1 being connected between the node 3 of the input path and the base of the transistor 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a low-noise amplifier circuit used for signal amplification in a wireless communication device or the like that performs wireless transmission between electronic and electrical devices, and a high-frequency circuit, a high-frequency component, and a communication device using the low-noise amplifier circuit.

  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, refrigerators, standard televisions (SDTV), high-definition televisions (HDTVs), electronic devices such as cameras, videos, mobile phones, etc. In addition, it is adopted as a signal transmission means that replaces wired communication in an airplane, and wireless data transmission is performed between each electronic and electrical device.

As a wireless LAN standard, IEEE802.11a supports high-speed data communication of up to 54 Mbps using an OFDM (Orthogonal Frequency Division Multiples) modulation method, and the frequency band is 5 GHz. Is done. IEEE802.11b is a DSSS (Direct Sequence Spread Spectrum) system that supports high-speed communication at 5.5 Mbps and 11 Mbps, and can be freely used without a radio license. The 4 GHz ISM (Industrial, Scientific and Medical) band is used. IEEE802.11g supports a high-speed data communication of a maximum of 54 Mbps using the OFDM modulation method, and uses the 2.4 GHz band as in the case of IEEE802.11b.
In the following description, IEEE802.11b and IEEE802.11g will be described as the first communication system (11bg), and IEEE802.11a will be described as the second communication system (11a).

  A multiband communication device using such a wireless LAN is described in Patent Document 1. A high-frequency circuit used in the multiband communication apparatus includes two dual-band antennas that can transmit and receive in two communication systems (IEEE802.11a and IEEE802.11b) having different communication frequency bands, a transmission-side circuit, and a reception-side circuit. A high-frequency switch having four ports for switching the connection between the high-frequency switch, a branching circuit arranged between one port of the high-frequency switch and the transmission-side circuit, and between another port of the high-frequency switch and the reception-side circuit And a branching circuit arranged in the above, and capable of receiving diversity. In particular, FIG. 20 of Patent Document 1 discloses a configuration in which a low-noise amplifier circuit that amplifies a weak reception signal and improves reception sensitivity is provided at the first reception terminal and the second reception terminal. Yes.

  FIG. 2 of Patent Document 2 discloses an example of a low noise amplifier (low noise amplifier circuit). The low noise amplifier disclosed in FIG. 2 of Patent Document 2 includes a feedback network coupled between the input and output of the amplifier, the feedback network including a DC blocking element and a resistor connected in series to the DC blocking element. Contains elements. In Patent Document 2, it is supposed that a high gain can be obtained by such a configuration.

WO 2006/003959 JP 2004-248252 A

  In the low noise amplifier disclosed in Patent Document 2, a high gain can be expected. However, when a low noise amplifier (low noise amplifier) is used in a wide band such as a multiband communication device using different frequency bands, high gain characteristics can be obtained at a low frequency, but low noise at a high frequency. In some cases, only a low gain characteristic can be obtained due to the frequency characteristic of the amplifier. In addition, since the input saturation power is proportional to the gain characteristic, if the gain characteristic is too high, the reception signal is prevented from being efficiently amplified by saturation of the low noise amplifier itself. For this reason, the frequency dependence of the gain characteristic is required to be flat. In order to meet such requirements, the configuration of the low noise amplifier is not necessarily sufficient, and a low noise amplifier with a flat gain characteristic has been desired.

  In view of the above-described problems, the present invention flattens gain characteristics in a low noise amplifier circuit used for signal amplification in a wireless communication device or the like, and a low noise amplifier circuit suitable for wide band use, and a high frequency circuit using the same, A high-frequency component and a communication device are provided.

  The low noise amplifier circuit of the present invention is a low noise amplifier circuit having a transistor, an input path connected to the base of the transistor, and an output path connected to the collector of the transistor, the node of the output path And a node of the input path through a resistor, and a capacitor is connected between the node of the input path and the base of the transistor. According to this configuration, the gain characteristic of the low noise amplifier circuit can be flattened.

  In the low noise amplifier circuit, an inductance element is preferably connected in series with the resistor of the feedback circuit. Since the impedance of the inductance element increases at a high frequency, it is possible to reduce the feedback amount at a higher frequency than at a lower frequency. Therefore, according to this configuration, the gain characteristic at a high frequency can be set high, and the frequency dependence of the gain characteristic can be further flattened.

  Furthermore, in the low noise amplifier circuit, a DC cut capacitor is provided on the opposite side of the capacitor across the node in the input path, and the capacitance value of the capacitor is smaller than the capacitance value of the DC cut capacitor. preferable. The capacitance value of the DC cut capacitor is set so as to be almost short in the operating frequency band. By making the capacitance value of the capacitor smaller than the capacitance value of the DC cut capacitor, the capacitor can effectively function as a part of the matching circuit in the operating frequency band. In addition, since the capacitance value of the capacitor can be reduced as compared with the case where the capacitor is provided in the feedback circuit as shown in FIG. 2 of Patent Document 2, the rise of the signal by ON / OFF control of the base voltage of the transistor is accelerated. Can do.

  The high-frequency circuit of the present invention includes an antenna terminal connected to an antenna capable of transmitting and receiving, a transmission terminal to which a transmission signal is input, a reception terminal to which a reception signal is output, the antenna terminal, and the transmission terminal or A switch circuit for switching connection with the reception terminal, and any one of the low-noise amplifier circuits is provided between the switch circuit and the reception terminal. If the low-noise amplifier circuit having the above-described configuration is used, a high-frequency circuit suitable for broadband transmission / reception can be provided. In addition, the signal rise time in the high-frequency circuit can be shortened.

  Another high-frequency circuit of the present invention is a high-frequency circuit used in a multiband radio apparatus that performs radio communication selectively using two or more different frequency bands, and can transmit and receive in the different frequency bands. An antenna terminal connected to an antenna; two or more transmission terminals to which transmission signals of different frequency bands are input; two or more reception terminals to which reception signals of different frequency bands are output; and the antenna terminal; A switch circuit for switching the connection with the transmission terminal or the reception terminal, and a demultiplexing circuit provided between the switch circuit and the two or more reception terminals, the switch circuit and the demultiplexing Any one of the low-noise amplifier circuits is provided between the circuit and the circuit. By providing the low-noise amplifier circuit having excellent gain characteristic flatness in the reception path of a high-frequency circuit used in a multiband radio apparatus, a high-frequency circuit having excellent gain characteristics can be provided.

  Furthermore, in the high-frequency circuit, it is preferable that a deviation of the low-noise amplifier circuit gain in the two or more different frequency bands is 5 dB or less. According to such a configuration, two or more different frequency bands can be handled by one low noise amplifier circuit.

  The high-frequency component of the present invention is a high-frequency component having any one of the high-frequency circuits, wherein the high-frequency circuit is formed by stacking and integrating electrode patterns on a plurality of layers, and the stacked body. It is characterized by comprising elements mounted on the surface. If a low noise amplifier circuit having excellent flatness of gain characteristics is used, a high-frequency component having excellent gain characteristics can be provided. In addition, the number of low-noise amplifier circuits to be used can be reduced, which contributes to the miniaturization of high-frequency components in combination with the lamination integration.

  Moreover, you may comprise a communication apparatus using the said high frequency component.

  According to the present invention, a gain characteristic is flattened in a low-noise amplifier circuit used for signal amplification in a wireless communication apparatus or the like, and a low-noise amplifier circuit suitable for use in a wide band, and a high-frequency circuit, a high-frequency component, and a communication using the same. Providing equipment. For example, a low-noise amplifier circuit, a high-frequency circuit, and a high-frequency circuit that can be shared by two or more communication systems such as IEEE802.11b using the wireless LAN 2.4 GHz band and / or IEEE802.11g and IEEE802.11a using the 5 GHz band. A configuration suitable for a component and a communication apparatus using the component is 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 a circuit diagram of a low noise amplifier circuit according to an embodiment of the present invention. The low noise amplifier circuit may 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). Assumed.

  The low noise amplifier circuit shown in FIG. 1 includes a transistor 1 and includes an input path connected to the base of the transistor 1 and an output path connected to the collector of the transistor 1. Further, the low noise amplifier circuit has a feedback circuit that feeds back a part of the output to the input and performs input / output matching in a wide band. The feedback circuit connects a node 2 on the output path between the output terminal Out_LNA and the collector and a node 3 on the input path between the input terminal IN_LNA and the base via the resistor RL2. In the low noise amplifier circuit shown in FIG. 1, a capacitor CL1 is further connected between the node 3 of the input path and the base of the transistor 1. This is one of the features of the present invention. Here, a conventional low-noise amplifier circuit is shown in FIG. In the conventional example shown in FIG. 8, the capacitor CL1 is connected in series to the feedback circuit. The capacitor CL1 is connected to separate the base-side voltage and the collector-side voltage and to feed back the passband signal from the output side to the input side of the low-noise amplifier circuit, as shown in FIG. For example, in a 2 to 6 GHz band, it is necessary to set a large capacitance value of about 15 pF in the feedback circuit. On the other hand, when the capacitor CL1 is arranged at the position in the embodiment shown in FIG. 1, the feedback amount can be determined only by the resistor RL2, so that there is no need for a large capacitance value. The capacitor CL1 has a function of separating the voltage on the base side and the voltage on the collector side and a part of the function of the input matching circuit. For example, the capacitor CL1 is set to a low capacitance value of about 2 pF in the 2.4 GHz band. CL1 can be used as part of the matching circuit. Since the capacitance value of the capacitor to be used can be reduced, it is possible to shorten the time required for signal rise by ON / OFF control of the base voltage of the transistor. Employing the arrangement of the capacitor CL1 shown in FIG. 1 further brings the following important effects. That is, by connecting the capacitor CL1 between the node 3 of the input path and the base of the transistor 1, the gain characteristic of the low noise amplifier circuit can be made flat. This is because the impedance of the capacitor CL1 is inversely proportional to the frequency. In other words, by setting the capacitor CL1 to an appropriate value, it acts as a high impedance at a low frequency and acts as a low impedance at a high frequency, so that the frequency dependence of gain characteristics can be flattened. In the configuration of FIG. 8 in which the capacitor CL2 is provided in the feedback circuit, the gain characteristic has a peak, which is insufficient when a broadband characteristic is required. On the other hand, if the configuration shown in FIG. 1 is adopted, a broadband low-noise amplifier circuit can be provided. Such a configuration is suitable for amplification of received signals in a multiband communication system. If the gain deviation in two or more different frequency bands is set to 5 dB or less with the above configuration, a high frequency circuit for multiband communication having an excellent receiving side circuit can be realized. This high-frequency circuit will be further described later. According to the configuration shown in FIG. 1, for example, it is shared by 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). Thus, an excellent low noise amplifier circuit is realized.

  The low noise amplifier circuit will be further described with reference to FIG. In the configuration of FIG. 1, the emitter of the transistor 1 is grounded. A power supply terminal Vcc is connected to the output path via an inductor LL1, and a direct current is supplied from the terminal. The inductor LL1 functions as a choke inductor, and prevents a high-frequency signal in the passband from leaking to the power supply in combination with the ground capacitor CL4. A control power supply terminal Vb is connected between the capacitor CL1 and the base of the input path via a resistor RL1. Resistor RL1 adjusts the operating point of the low noise amplifier circuit. Further, a DC cut capacitor CL2 is connected between the node 3 of the input path and the input terminal In_LNA. A DC cut capacitor CL3 is also connected between the node 2 on the one output path and the output terminal Out_LNA. In addition, the structure which concerns on a power supply and a control power supply is not restricted to what is shown in a figure, Another structure can also be used. For example, as shown in FIG. 2, one power supply terminal Vcc may be provided and the power supply may be shared. In this configuration, one power supply terminal Vcc is connected to the input path via the resistor RL1 and to the output path via the inductor LL1. According to such a configuration, on / off control of the low-noise amplifier circuit can be performed with one power source, the circuit is simplified, contributing to downsizing and cost reduction.

  As described above, the capacitor CL1 in the embodiment of FIGS. 1 and 2 is different in arrangement and function from the DC cut capacitor CL2 that is also used in the conventional low noise amplifier circuit. That is, the configuration in which the DC cut capacitor is provided is a configuration in which the DC cut capacitor CL2 is provided on the opposite side of the capacitor CL1 with the node 3 interposed in the input path. In this case, the capacitance value of the capacitor CL1 is made smaller than the capacitance value of the DC cut capacitor CL2. The capacitance value of the DC cut capacitor is set so that it can be regarded as a short circuit in the use frequency band, but the capacitor CL1 is set to have a capacitance value so as to maintain the impedance in order to function effectively as a capacitor in the use frequency band.

  FIG. 3 shows another embodiment according to the present invention. In the configuration shown in FIG. 3, an inductance element LL2 is connected in series with the resistor RL2 of the feedback circuit. Since the impedance of the inductance element increases at a high frequency, it is possible to reduce the feedback amount at a higher frequency than at a lower frequency. Therefore, according to the configuration of FIG. 3, the gain characteristic at a high frequency can be set high, and the frequency dependence of the gain characteristic can be further flattened. At this time, in order to improve the gain characteristics and flatten the frequency dependence, the inductance element having a characteristic that the self-resonant frequency is larger than the pass band used and the Q value in the pass band is 10 or more is used. It is desirable to do.

  Next, an embodiment of a high frequency circuit using the low noise amplifier circuit will be described. FIG. 4 shows a dual band that handles a 2.4 GHz band wireless LAN and a 5 GHz band wireless LAN as a specific example of a high frequency circuit used in a multiband wireless apparatus that performs wireless communication selectively using two or more different frequency bands. The high frequency circuit is shown. The high-frequency circuit includes an antenna terminal Ant connected to an antenna capable of transmitting and receiving in different frequency bands of 2.4 GHz and 5 GHz, and transmission terminals Tx_b and Tx_a to which transmission signals of 2.4 GHz and 5 GHz frequency bands are input, respectively. Reception terminals Rx_b and Rx_a from which reception signals of 2.4 GHz and 5 GHz are output are provided. Further, the high-frequency circuit is provided between the antenna terminal Ant and the switch circuit (SPDT1) 101 that switches connection between the transmission terminals Tx_b and Tx_a or the reception terminals Rx_b and Rx_a, and the switch circuit 101 and the reception terminals Rx_b and Rx_a. The demultiplexing circuit (Dip1) 103 is provided. For example, a low noise amplifier circuit (LNA) 109 according to the present invention shown in FIG. 1 is provided between the switch circuit 101 and the demultiplexing circuit 103.

  The high-frequency circuit shown in FIG. 4 will be further described in detail. In the high frequency circuit of the circuit block shown in FIG. 4, a detection circuit (DET) 102 is connected between the transmission path side of the switch circuit 101 and the demultiplexing circuit 103. The first demultiplexing circuit 103 includes 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 transmission signal. Attenuate. 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. A first power amplifier circuit (PA1) 105 is connected to the low-frequency filter circuit of the first branching circuit 103, and a first bandpass filter circuit (BPF1) 107 is connected to the first power amplifier circuit 105. Connected to the transmission terminal Tx_b of the 2.4 GHz band wireless LAN. Here, the band pass filter circuit 107 removes unnecessary noise outside the band included in the transmission signal, and the first power amplifier circuit 105 receives the transmission signal input from the transmission side circuit of the 2.4 GHz band wireless LAN. The low frequency side filter circuit of the first branching circuit 103 amplifies and attenuates the harmonic signal generated in the first power amplifier circuit 105. A low-pass filter (LPF) 104 is connected to the high-frequency filter circuit of the first demultiplexing circuit 103, and a second power amplifier circuit (PA2) 106 is further connected to the second power amplifier circuit 106. Two band pass filter circuits (BPF2) 108 are connected to a transmission terminal Tx_a of a 5 GHz band wireless LAN. Here, the bandpass filter circuit 108 removes unnecessary noise outside the band included in the transmission signal, and the second power amplifier circuit 106 amplifies the transmission signal input from the transmission side circuit of the 5 GHz band wireless LAN. The low-pass filter 104 allows the amplified transmission signal to pass through, but has the effect of attenuating the harmonic signal generated by the second power amplifier circuit 106. Further, a low noise amplifier circuit 109 is connected to the reception path side of the switch circuit 101, and then a second branching circuit (Dip2) 110 is connected. The low noise amplifier circuit 109 amplifies the reception signal of the 2.4 GHz band wireless LAN and the reception signal of the 5 GHz band wireless LAN. It is desirable to use the low noise amplifier circuit according to the present invention to cover a wide band so as to amplify received signals of 2.4 GHz band and 5 GHz band wireless LAN. It is also possible to adopt a configuration in which a low noise amplifier circuit is provided in each of two reception paths branched by a branching circuit, as in a circuit configuration generally used in the prior art. However, according to the circuit configuration, since it is not necessary to use two low-noise amplifier circuits, it is possible to reduce the size and cost, and further, a demultiplexing circuit and a bandpass are provided on the input side of the low-noise amplifier circuit. Since there is no need to use a circuit, the reception sensitivity can be improved. The second demultiplexing circuit 110 includes a low frequency side filter circuit and a high frequency side filter circuit, and the low frequency side filter circuit passes a reception signal of the 2.4 GHz band wireless LAN and transmits a reception signal of the 5 GHz band wireless LAN. Attenuate. 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. As a result, the signal amplified by the low noise amplifier circuit is demultiplexed by the second demultiplexing circuit 110, and the 2.4 GHz band wireless LAN received signal is passed through the third bandpass filter circuit (BPF 3) 111. 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 detection circuit 102 is provided between the switch circuit 101 and the first branching circuit 103. This detection circuit can be provided between the first demultiplexing circuit 103 and each of the power amplifier circuits 105 and 106, but in this case, two detection circuits are required, which is suitable for downsizing. Absent. In addition, a detection output can be provided in each of the power amplifier circuits 105 and 106. In this detection circuit 102, 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 or the like and used for controlling the power amplifier circuits 105 and 106. . In addition, a low-pass filter circuit can be provided between the first branching circuit 103 and the first power amplifier circuit 105. As a result, the transmission signal amplified by the first power amplifier circuit 105 is allowed to pass, but the harmonic signal generated by the first power amplifier circuit 105 can be attenuated. In addition, a band pass filter circuit may be provided between the second demultiplexing circuit 110 and the reception terminal Rx_a of the 5 GHz band wireless LAN. The switch circuit 101 has a switching element such as a field effect transistor (FET) or a diode as a main component, and can be configured by using an inductance element and a capacitance element as appropriate, and has an SPDT (Single Pole Dual Throw) type switching function. What is necessary is just to use. As described above, the arrangement of the filter circuit and the detection circuit can be changed according to the required characteristics.

  The high frequency circuit using the low noise amplifier circuit according to the present invention is not limited to the above embodiment. The present invention can be applied not only to a dual band but also to a high frequency circuit for a multiband radio apparatus that performs radio communication by selectively using two or more different frequency bands such as a triple band. By using the low noise amplifier circuit according to the present invention, the gain deviation of the low noise amplifier circuit in two or more different frequency bands can be suppressed to, for example, 5 dB or less, and an excellent high frequency circuit can be realized. it can. On the other hand, not only multiband but also a high-frequency circuit used for a single-band radio device can be configured. FIG. 5 shows a high-frequency circuit used in a single-band radio apparatus using one frequency band. The high-frequency circuit shown in FIG. 5 includes an antenna terminal Ant connected to an antenna capable of transmitting and receiving, a transmission terminal Tx to which a transmission signal is input, a reception terminal Rx to which a reception signal is output, an antenna terminal Ant, and a transmission terminal. The switch circuit 101 switches the connection to Tx or the reception terminal Rx. A low noise amplifier circuit 109 according to the present invention is provided between the switch circuit 101 and the reception terminal Rx. In the configuration shown in FIG. 5, a low-pass filter circuit 104 is connected between the detection circuit 102 and the switch circuit 101. Since the other configuration is the same as the configuration shown in FIG. 4, the description thereof is omitted.

  The high-frequency circuit can be provided with a high-frequency component by forming a laminated body in which electrode patterns are formed and integrated in a plurality of layers and an element mounted on the surface of the laminated body. Examples of the laminate include a ceramic laminate substrate and a resin substrate. The configuration of the high-frequency component will be described taking a ceramic laminated substrate as an example. FIG. 6 is a perspective view showing an embodiment of the high-frequency component according to the present invention, in which the mounted component is mounted on the ceramic multilayer substrate 200. The transistor 1, resistors RL1 and RL2, capacitor CL1, inductor LL1, and DC cut capacitors CL1 and CL2, which constitute the low noise amplifier circuit shown in FIG. 1, together with the switch circuit SPDT1 and the first and second power amplifier circuits PA1 and PA2 It is mounted on the ceramic laminated substrate 200. A part of circuit elements such as L and C constituting a circuit such as a filter used in the high frequency switch circuit is formed by an electrode pattern inside the ceramic multilayer substrate 200, and the remaining part is formed as a chip component on the ceramic multilayer substrate 200 It is installed.

The ceramic multilayer substrate 200 is made of a ceramic dielectric material LTCC (Low Temperature Co-fired Ceramics) that can be sintered at a low temperature of 1000 ° C. or less, for example, on a green sheet having a thickness of 10 μm to 200 μm, a low resistivity Ag, It can be manufactured by printing a conductive paste such as Cu to form a predetermined electrode pattern, appropriately stacking 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 is a metal conductor that can be sintered at a high temperature such as tungsten or molybdenum. You may comprise as.

  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 IEEE802.11h) may be used for the high frequency circuit described above or a high frequency component using a ceramic multilayer substrate. ) Can be used in common, and a small multiband communication device including the same 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. Further, not only two communication systems but also a high-frequency switch circuit that is switched in multiple stages, for example, can support a larger number of communication systems. Examples of multiband communication devices include wireless communication devices typified by mobile phones, personal computers (PCs), PC peripherals such as printers and hard disks, broadband routers, fax machines, refrigerators, standard televisions (SDTV), and high-definition televisions. (HDTV), camera, video, etc. can be deployed in home electronic devices.

  In the circuit of FIG. 1, when the constant CL1 of the peripheral circuit of the low-noise amplifier is 2 pF, RL2 is 560 Ω, CL2 and CL3 are 15 pF, CL4 is 100 pF, RL1 is 56 kΩ, and LL1 is 8.2 nH (Example 1) Figure 2 shows the gain characteristics when the constant CL1 is 2 pF, RL2 is 560 Ω, CL2 and CL3 are 15 pF, CL4 is 100 pF, RL1 is 56 kΩ, LL1 is 8.2 nH, and LL2 is 3.9 nH (Example 2). 7 shows. Further, in the conventional circuit shown in FIG. 8, the peripheral circuit constant CL1 is 15 pF, RL2 is 560 Ω, CL2 and CL3 are 15 pF, CL4 is 100 pF, RL1 is 56 kΩ, and LL1 is 8.2 nH (comparative example). The characteristics are shown in FIG. In the configuration of the comparative example, the gain deviation in the frequency range of 2.4 GHz to 5.85 GHz was as large as 5 dB, and the rise of the signal by ON / OFF control of the base voltage of the transistor was 0.8 μsec. In contrast, in the first embodiment, the gain on the low frequency side of 1 to 2 GHz is suppressed, and in the frequency range of 2.4 GHz to 5.85 GHz, the gain deviation is 2 dB or less while ensuring 12 dB or more. The rise of the signal due to the ON / OFF control of the base voltage was 0.1 μsec. With the configuration of Example 1, characteristics suitable for the dual band of 2.4 GHz band and 5 GHz band could be obtained. Further, in Example 2 in which LL2 is arranged in the feedback circuit, the gain in the vicinity of 5 GHz increases, the gain deviation is 1 dB or less, and the rise of the signal by the ON / OFF control of the base voltage of the transistor is 0.1 μsec. That is, a low-noise amplifier circuit with a small gain deviation and excellent gain flatness was realized. Furthermore, in the configuration of the second embodiment, a gain of 13 dB or more is obtained in the frequency range of 2.4 GHz to 5.85 GHz. Thus, it is clear that the circuit of FIG. 1 according to the present invention is superior to the conventional circuit.

It is a figure which shows embodiment of the low noise amplifier circuit based on this invention. FIG. 6 is a diagram showing another embodiment of a low noise amplifier circuit according to the present invention. FIG. 6 is a diagram showing another embodiment of a low noise amplifier circuit according to the present invention. 1 is a circuit block showing an embodiment of a high-frequency circuit according to the present invention. It is a circuit block which shows other embodiment of the high frequency circuit which concerns on this invention. It is a perspective view which shows embodiment of the high frequency component which concerns on this invention. It is a figure which shows the gain characteristic of a low noise amplifier circuit. It is a figure which shows the conventional low noise amplifier circuit.

Explanation of symbols

1: Transistor 2, 3: Node 101: High-frequency switch circuit 102: Detection circuit 103, 110: Demultiplexing circuit 104: Low-pass filter circuit 105, 106: Power amplifier circuits 107, 108, 111: Band-pass filter circuits 109, 109a: Low noise amplifier circuits CL1-4: capacitors,
RL1,2: Resistance LL1,2: Inductance element Vb: Control power supply terminal Vcc: Supply power supply terminal
In_LNA: Input terminal
Out_LNA: Output terminal

Claims (8)

A low noise amplifier circuit having a transistor, an input path connected to a base of the transistor, and an output path connected to a collector of the transistor,
A feedback circuit that connects a node of the output path and a node of the input path via a resistor;
A low noise amplifier circuit, wherein a capacitor is connected between a node of the input path and a base of the transistor.   The low noise amplifier circuit according to claim 1, wherein an inductance element is connected in series with the resistor of the feedback circuit.   3. A DC cut capacitor on the opposite side of the capacitor across the node in the input path, wherein the capacitance value of the capacitor is smaller than the capacitance value of the DC cut capacitor. A low noise amplifier circuit as described. An antenna terminal connected to an antenna capable of transmitting and receiving;
A transmission terminal to which a transmission signal is input; and
A receiving terminal for outputting a received signal;
The antenna terminal, and a switch circuit that switches connection between the transmission terminal or the reception terminal,
A high-frequency circuit comprising the low-noise amplifier circuit according to claim 1 between the switch circuit and the receiving terminal. A high-frequency circuit used in a multiband wireless device that performs wireless communication selectively using two or more different frequency bands,
An antenna terminal connected to an antenna capable of transmitting and receiving in the different frequency bands;
Two or more transmission terminals to which transmission signals of the different frequency bands are input; and
Two or more receiving terminals from which received signals of different frequency bands are output;
A switch circuit for switching connection between the antenna terminal and the transmission terminal or the reception terminal;
A demultiplexing circuit provided between the switch circuit and the two or more receiving terminals;
A high-frequency circuit comprising the low-noise amplifier circuit according to claim 1 between the switch circuit and the branching circuit.   6. The high frequency circuit according to claim 5, wherein a deviation in gain of the low noise amplifier circuit in the two or more different frequency bands is 5 dB or less. A high-frequency component having the high-frequency circuit according to any one of claims 4 to 6,
The high frequency circuit includes a laminated body in which electrode patterns are formed in a plurality of layers and laminated and integrated, and an element mounted on a surface of the laminated body. A communication apparatus using the high-frequency component according to claim 7.

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