JP4224802B2 - High-pass filter, multiband antenna switch circuit using the same, multiband antenna switch laminated module, and communication apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency composite component such as a high-pass filter, a multi-band antenna switch circuit, and a multi-band antenna switch laminated module used in a high-frequency band such as a microwave band, and more particularly to a high-frequency switch component that handles a transmission / reception system with a single antenna. It relates to electric surge countermeasures.
[0002]
[Prior art]
For example, EGSM (Extended Global System for Mobile Communications) method and DCS (Digital Cellular System) method, which are popular in Europe, PCS (Personal Communication Service) method, which is popular in the United States, are adopted in Japan. There are various systems such as PDC (Personal Digital Cellular) system, but with the rapid spread of mobile phones in recent years, the system is used in the frequency band allocated to each system, especially in major metropolitan areas in developed countries. There are problems such as being unable to cover the party, making it difficult to connect, and disconnecting during a call. Therefore, it has been proposed that the user can use a plurality of systems to increase the number of frequencies that can be substantially used, and further expand the service area and effectively use the communication infrastructure of each system.
[0003]
When the user wants to use a plurality of systems, the user needs to have a portable communication device corresponding to each system, or a small and lightweight portable communication device that can communicate with the plurality of systems. In the latter case, in order to be able to use a plurality of systems with one portable communication device, the portable communication device may be configured using components for each system. However, in the signal transmission system, for example, desired transmission High-frequency switches such as filters that pass transmission signals of frequencies, high-frequency switches that switch transmission / reception circuits, antennas that receive and emit transmission / reception signals, and filters that pass the desired frequency of reception signals that have passed through the high-frequency switch in signal reception systems Circuit components are required for each system. For this reason, the portable communication device becomes expensive and increases in volume and weight, which is not suitable for portable use. Therefore, small and lightweight high-frequency circuit components corresponding to a plurality of systems have become necessary. For example, a dual-band antenna switch module compatible with EGSM and DCS or a triple-band antenna switch module used in a portable communication device compatible with three systems of EGSM, DCS, and PCS is disclosed in JP-A-11-225088 and JP-A-2000-165288, US Pat. No. 5,815,804, and the like, respectively.
[0004]
As an example, a block diagram of a triple band antenna switch module corresponding to EGSM, DCS, and PCS is shown in FIG. A demultiplexer (diplexer) Dip demultiplexes 0.9 GHz band EGSM signals and 1.8 GHz band DCS / PCS signals, switch SW1 switches EGSM transmission and reception, and SW2 switches transmission and reception of DCS and PCS. The low-pass filters LPF1 and LPF2 reduce the amount of harmonic distortion generated by the power amplifier on the transmission side. The SAW filters SAW1, SAW2, and SAW3 play a role of reducing noise outside the reception band included in the reception signal. In this case, a PIN diode switch using a PIN diode or a GaAs FET switch is used for SW1 and SW2.
[0005]
High-frequency components such as PIN diodes, GaAs FETs, and SAW filters used in the antenna switch module described above are vulnerable to electrostatic surges, especially in the case of mobile phones, when the electrostatic surge from the human body is input to the antenna. There was a problem that high-frequency components were destroyed.
[0006]
In addition, even if the antenna switch module is not destroyed, there is a possibility of destroying a circuit connected to the subsequent stage of the antenna switch module such as a power amplifier connected to the transmission terminal and a low noise amplifier connected to the reception terminal. Yes, it was important to take measures against electrostatic surges.
[0007]
JP-A-2001-44883 and JP-A-2001-186047 are examples of conventional techniques related to countermeasures against electrostatic surges. FIG. 14 shows countermeasures against electrostatic surges disclosed in Japanese Patent Laid-Open No. 2001-44883. In this example, inductors L1, L2, and L3 connected to the ground and capacitors C1, C2, and C3 are inserted into the signal lines of the antenna terminal ANT, the transmission terminal Tx, and the reception terminal Rx (enclosed by dotted lines). Part). However, this countermeasure requires an inductor and a capacitance for each of the antenna terminal, transmission terminal, and reception terminal as countermeasures against electrostatic surges. It was also a cause of deterioration.
[0008]
Next, FIG. 15 shows a countermeasure against electrostatic surge disclosed in Japanese Patent Laid-Open No. 2001-186047. This was the one in which the inductor L3 connected to the ground was inserted into the low-frequency-band duplexer Dip1 of the two duplexers (the portion surrounded by the dotted line inside). In other words, as an electrostatic surge countermeasure, an inductor is added to a part of the duplexer, but in actuality, as shown in FIG. It was not enough to prevent electrostatic surges.
[0009]
Furthermore, as shown in FIG. 16, in the case of a circuit that directly switches transmission / reception signals of a plurality of frequencies with a GaAs FET switch without using a duplexer, it is necessary to incorporate an electrostatic surge countermeasure circuit between the antenna and the GaAs switch. However, in order to protect the GaAs switch from electrostatic surges, it is necessary to set the inductor falling to the ground to 5 nH or less. However, when an inductor of 5 nH or less is connected to the antenna top, it becomes difficult to achieve matching in a wide band from 900 MHz band to 1.8 GHz band. Therefore, the conventional electrostatic surge countermeasure circuit cannot be used for the antenna top.
[0010]
In addition, varistors and Zener diodes can also be used as anti-static surge countermeasure components. In this case, however, it is necessary to increase the capacitance between the terminals. It could not be used as a countermeasure against electrostatic surges in the circuit.
[0011]
In view of the above, the present invention solves the above-described problems in the prior art, can achieve matching in a wide band, and can be used at the antenna top, and a high-pass filter for countermeasures against electrostatic surges and a multiband antenna using the same It is an object of the present invention to provide a switch circuit, a multiband antenna switch laminated module, and a communication device.
[0012]
[Means for Solving the Problems]
A first invention is a high-pass filter having a high-pass filter circuit and a series resonance circuit between an input terminal and an output terminal, wherein the high-pass filter circuit releases an electrostatic surge to the ground. A first inductor connected between the input terminal and the ground; and a first capacitor connected between the input terminal and the output terminal, wherein the series resonant circuit includes the output terminal and the ground. The second inductor and the second capacitor connected between each other, have a resonance frequency between 100 MHz and 500 MHz, S. W. R is 1.3 or less at 1 GHz to 2 GHz, and is a high-pass filter that is excellent in attenuation at 300 MHz or less and is used for countermeasures against electrostatic surges.
Here, a parallel resonance circuit including a third inductor and a third capacitor may be provided between the series resonance circuit and the output terminal.
[0013]
In the present invention, a parallel resonance circuit including a third inductor and a third capacitor may be disposed between the series resonance circuit and the output terminal.
[0014]
The output end side of the Mataha bypass filters may be connected to the SAW filter.
[0015]
A second invention is a switch circuit characterized in that a switch is connected to the output end side of the high-pass filter circuit of the first invention.
[0016]
A third invention is a switch circuit characterized in that a switch is connected to the input end side of the high-pass filter of the first invention.
[0017]
A fourth invention is a communication device using the high-pass filter of the first invention.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a high-pass filter for electrostatic surge countermeasures and a multiband antenna switch circuit using the same according to the present invention will be described with reference to the drawings.
(Example 1)
FIG. 1 shows an embodiment of a high-pass filter circuit for electrostatic surge countermeasures according to the present invention. In FIG. 1, the inductor L1 is connected between the input terminal P1 and the ground, the capacitor C1 is inserted between the input terminal P1 and the output terminal P2, and the series resonant circuit including the inductor L2 and the capacitor C2 is connected to the output terminal P2. Connected to ground. In this case, by appropriately selecting the values of L1 and C1, a high-pass filter is configured such that electrostatic surges escape to the ground and high-frequency signals are transmitted with low loss. Here, L1 is desirably 50 nH or less, and C1 is desirably 10 pF or less. In addition, the series resonance circuit composed of L2 and C2 sets the values of L and C so that the resonance frequency is set between 100 MHz and 500 MHz. In this case, C2 is preferably 10 pF or more, and L2 is preferably 50 nH or less. As a result, the electrostatic surge in the resonance frequency band, which is a problem in electrostatic breakdown, can be absorbed to the ground, and countermeasures against electrostatic surge can be performed more efficiently.
[0019]
The breakdown due to electrostatic surge that can occur in an actual mobile terminal is assumed to be in contact with the antenna of the mobile terminal while the human body is charged. The Human Body Model is generally used as a method for experimentally reproducing this situation. Specifically, a device is used in which the charge state of the human body is replaced with an equivalent circuit as shown in FIG. 6 and the charge charged in the capacitor C is discharged to the device under test via the resistor R.
[0020]
When the human body model has a capacitance C = 150pF and resistance R = 330Ω, the discharge surge waveform is as shown in Fig. 7. When this waveform is Fourier transformed to obtain the frequency component of the discharge surge waveform, the spectrum as shown in Fig. 8 is obtained. Is obtained. From this frequency spectrum, the surge waveform from the human body is dominated by frequency components from DC to 300 MHz. As a countermeasure against electrostatic surges, a high-pass filter that can remove DC to 300 MHz and transmit high-frequency signals with low loss is used. It can be estimated that it is ideal.
[0021]
Therefore, the conventional electrostatic surge countermeasure circuit shown in FIG. 9 (Japanese Patent Laid-Open No. 2001-186047) and FIG. 10 (Japanese Patent Laid-Open No. 2001-44883) and the electrostatic surge countermeasure circuit of the present invention shown in FIG. The attenuation characteristics up to ~ 2GHz were measured. FIG. 11 shows attenuation characteristics, and FIG. 12 shows reflection characteristics. As a characteristic comparison, the signals to be passed were assumed to be 900 MHz band and 1800 MHz band indicated by Δ in the figure, and the reflection characteristics VSWR in each band were set to 1.5 or less as shown in FIG. The attenuation in the frequency band of 300 MHz or less, which is a problem in electrostatic breakdown due to the attenuation characteristics of FIG. 11, is 5 dB or less in the electrostatic surge countermeasure circuit of the prior art (FIGS. 9 and 10), whereas the present invention In the electrostatic surge countermeasure circuit (FIG. 1) of the present invention, it is 30 dB or more, and the electrostatic surge countermeasure circuit of the present invention can secure an attenuation of more than 25 dB. In other words, an electrostatic surge removal effect of 25 dB (17 times or more) can be obtained with respect to the electrostatic surge voltage as compared with the prior art.
[0022]
(Example 2)
Next, FIG. 2 shows another embodiment of a high-pass filter circuit for electrostatic surge countermeasures according to the present invention. In FIG. 2, the roles of the inductors L1 and L2 and the capacitors C1 and C2 are the same as those shown in the first embodiment. However, a parallel resonant circuit including the capacitor C3 and the inductor L3 is provided between the capacitor C1 and the output terminal P2. The insertion point is different from that of the first embodiment. This parallel resonant circuit functions to remove the harmonic noise signal transmitted from the antenna by setting it to have an attenuation pole at a frequency N times that of the transmission signal. In addition, by adjusting the values of C3 and L3, the matching of the entire electrostatic surge circuit can be adjusted, which is more effective.
[0023]
(Example 3)
FIG. 3 is a block diagram showing an embodiment of a triple band antenna switch circuit using a high-pass filter for countermeasures against electrostatic surges according to the present invention. In this case, the demultiplexer Dip plays a role of demultiplexing and synthesizing a signal in the EGSM band (880 to 960 MHz) and a signal in the DCS / PCS band (DCS: 1710 to 1880 MHz, PCS: 1850 to 1990 MHz). The switch circuit SW1 switches between EGSM transmission signals and reception signals, and SW2 switches between DCS / PCS transmission signals, DCS reception signals, and PCS reception signals using SP3T (Single Pole 3 Throw) switches. The low-pass filter LPF1 plays a role of attenuating the Nth order harmonic distortion contained in the transmission signal input from the EGSM TX terminal, and the LPF2 reduces the Nth order harmonic distortion contained in the transmission signal inputted from the DCS / PCS TX terminal. It plays a role to attenuate. The SAW filters SAW1, SAW2, and SAW3 are responsible for removing noise outside the reception band included in the EGSM reception signal, the DCS reception signal, and the PCS reception signal, respectively.
[0024]
In FIG. 3, the electrostatic surge countermeasure circuit of the present invention is inserted between the antenna terminal ANT and the duplexer Dip, and plays a role of absorbing the electrostatic surge input from the antenna terminal ANT to the ground. Therefore, by the electrostatic surge countermeasure circuit of the present invention, a circuit such as a DIP diode switch or a GaAs FET switch, a reception SAW filter, a power amplifier connected to the transmission terminal, and a low noise amplifier connected to the reception terminal is configured. Can be protected from electrostatic surges.
[0025]
Further, the parallel resonant circuit composed of the inductor L3 and the capacitor C3 shown in the dotted line frame is shown as a circuit that can be added as an option (the same applies to the following embodiments). When this parallel resonant circuit is provided, the attenuation pole is adjusted to a frequency twice that of DCS / PCS Tx (3420MHz to 3820MHz), so that the frequency four times that of EGSM transmission (3520MHz to 3660MHz) is also attenuated at the same time. Therefore, DCS / PCS transmission double attenuation and EGSM transmission quadruple attenuation can be attenuated simultaneously. Further, since the parallel resonant circuits L3 and C3 also have a function as a matching circuit, they are useful for matching adjustment of the entire antenna switch.
[0026]
(Example 4)
FIG. 4 is a block diagram showing an embodiment of a triple-band antenna switch circuit in which a high-pass filter for preventing electrostatic surge according to the present invention is inserted between an antenna ANT and a GaAs FET switch. In this case, the SP5T (Single Pole 5 Throw) switch switches the EGSM transmission signal, EGSM reception signal, DCS / PCS transmission signal, DCS reception signal, and PCS reception signal among the signals input / output from the antenna terminal to the specified terminal. Do. The low-pass filter LPF1 plays a role of attenuating the Nth order harmonic distortion contained in the transmission signal input from the EGSM TX terminal, and the LPF2 reduces the Nth order harmonic distortion contained in the transmission signal inputted from the DCS / PCS TX terminal. It plays a role to attenuate. The SAW filters SAW1, SAW2, and SAW3 are responsible for removing noise outside the reception band included in the EGSM reception signal, the DCS reception signal, and the PCS reception signal, respectively.
[0027]
In FIG. 4, the electrostatic surge countermeasure circuit of the present invention is inserted between the antenna terminal and the SP5T switch, and absorbs the electrostatic surge input from the antenna to the ground. Therefore, the electrostatic surge countermeasure circuit of the present invention can protect circuits such as the SP5T switch, the reception SAW filter, the power amplifier connected to the transmission terminal, and the low noise amplifier connected to the reception terminal from electrostatic surges.
[0028]
(Example 5)
FIG. 5 shows an embodiment of a triple band antenna switch circuit using a high-pass filter for electrostatic surges according to the present invention. In this case, the SP3T switch switches the EGSM transmission signal and DCS reception signal among the signals input / output from the antenna terminal to the demultiplexer Dip1, switches the DCS / PCS transmission signal and EGSM reception signal to the demultiplexer Dip2, and the PCS reception signal Switch to SAW for PCS reception. The low pass filter LPF1 plays a role of attenuating Nth order harmonic distortion included in the transmission signal input from the EGSMTX terminal, and LPF2 reduces Nth order harmonic distortion included in the transmission signal input from the DCS / PCS TX terminal. It plays a role to attenuate. The SAW filters SAW1, SAW2, and SAW3 are responsible for removing noise outside the reception band included in the EGSM reception signal, the DCS reception signal, and the PCS reception signal, respectively. The duplexer Dip1 is connected to LPF1 and SAW2, and the duplexer Dip2 is connected to LPF2 and SAW1.
[0029]
In FIG. 5, the electrostatic surge countermeasure circuit of the present invention is inserted between the antenna terminal ANT and the SP3T switch, and absorbs the electrostatic surge input from the antenna to the ground. Therefore, the electrostatic surge countermeasure circuit of the present invention can protect circuits such as the SP3T switch, the reception SAW filter, the power amplifier connected to the transmission terminal, and the low noise amplifier connected to the reception terminal from electrostatic surges. In addition, since the SP3T switch used in this example has a smaller circuit scale than SP5T, it can be reduced in size and cost than the high-frequency antenna switch module using the SP5T switch shown in Example 4. There are features.
[0030]
(Example 6)
The high-pass filter and antenna switch circuit for electrostatic surge countermeasures in the present invention constitute part of the inductor and the capacitor can be built in the dielectric multilayer substrate, while the part of the capacitance, inductor constituting the electrostatic surge countermeasure circuit, By mounting chip components such as PIN diode switch elements, GaAs FET switch elements, resistors, capacitors, and choke coils used as switch circuits on the dielectric multilayer substrate, a compact and inexpensive multiband antenna switch multilayer module composite component Is obtained.
[0031]
For example, FIG. 13 shows a perspective view of a composite part in which the antenna switch circuit module shown in the block diagram of FIG. Although not shown in the figure, the diplexers Dip1, Dip2, low-pass filters LPF1, LPF2, and the inductors and capacitors that make up the high-pass filter circuit for countermeasures against electrostatic surges are divided into multiple layers and printed in a small size. Can be made lighter and lighter. On the other hand, an SP3T GaAs FET switch 2, a SAW filter 3, a chip inductor 4, and a chip capacitor 5 are mounted on the multilayer body 1, respectively.
[0032]
In this embodiment, the multilayer substrate uses a ceramic dielectric material (LTCC) that can be fired at a low temperature of 950 ° C. or less, and the ceramic green sheet before firing has a sheet thickness so that a transmission line and a capacitor can be easily formed. The thing of 40-200 micrometers was used. A plurality of these ceramic green sheets are laminated, cut into individual pieces, printed with side electrodes, and then fired at 950 ° C. to obtain a laminated body of antenna switch laminated module composite parts. Furthermore, by mounting an SP3T GaAs FET switch, a chip inductor, and a chip capacitor on the obtained laminate, it is possible to obtain a compact antenna switch laminate module composite part with a countermeasure against electrostatic surges.
[0033]
(Other examples)
In the above embodiment, it is assumed that the electrostatic surge countermeasure circuit is connected to the antenna top, but the electrostatic surge countermeasure circuit of the present invention is characterized in that matching can be achieved in a sufficiently wide band from 900 MHz to 2 GHz. It is possible to insert not only the antenna top but also a plurality of places. For example, taking the block diagram of FIG. 17 as an example,
▲ 1 ▼ Dip-SW1 ▲ 2 ▼ Dip-SW2 ▲ 3 ▼ SW1-LPF1 ▲ 4 ▼ SW1-SAW1 ▲ 5 ▼ SW2-LPF2 ▲ 6 ▼ SW2-SAW2 ▲ 7 ▼ SW2-SAW3 and It can be provided at a position where these (1) to (7) are combined.
[0034]
Moreover, although the multiband antenna switch circuit corresponding to EGSM, DCS, and PCS was described in the above embodiment, other than this, W-CDMA band (1920 MHz to 2170 MHz), PDC800 band (810 to 960 MHz), DAMPS ( 824 to 849MHz), GPS band (1575.42MHz), PHS band (1895 to 1920MHz), Bluetooth band (2400 to 2484MHz), CDMA2000, which is expected to spread in the US, and TD-SCDMA, which is expected to spread in China Similar effects can be expected. Therefore, according to the present invention, it is possible to obtain a dual-mode, 3-band, 4-band, 5-band, etc. multimode multiband antenna switch circuit in which the amount of harmonic generation is suppressed, and to consolidate these functions in the laminate. I can do it. A communication device such as a mobile phone using such a laminate module is small in size and can reduce power consumption.
[0035]
【The invention's effect】
By using the electrostatic surge countermeasure circuit of the present invention, the electrostatic surge from the antenna terminal can be released to the ground, and the electrostatic surge can be absorbed with respect to a wide frequency band, so that the electrostatic breakdown countermeasure can be more completely implemented. DIP diode switches or GaAs FET switches, multi-band antenna switch circuits, receiving SAW filters, power amplifiers connected to transmission terminals, low-noise amplifiers connected to reception terminals are protected from electrostatic surges. And the subsequent high-frequency electronic components are not destroyed.
In addition, because the transmission line and part of the capacitance of the duplexer and switch circuit are built in and integrated with the multilayer substrate, the wiring between the duplexer and switch circuit is also formed on the surface of the multilayer substrate or inside the multilayer substrate. And the alignment adjustment between the two becomes easy. On the other hand, since chip components such as switch elements, resistors, capacitors, and inductors are mounted on the multilayer substrate, a small and high-performance antenna switch multilayer module composite component with a built-in electrostatic surge countermeasure circuit can be obtained.
In addition, a communication device using these multiband antenna switch circuits or multiband antenna switch laminated module composite parts is downsized and has low power consumption specifications.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a high-pass filter for electrostatic surge prevention according to the present invention.
FIG. 2 is a diagram showing another embodiment of the high-pass filter for electrostatic surge prevention according to the present invention.
FIG. 3 is a block diagram showing an embodiment of the multiband antenna switch circuit of the present invention.
FIG. 4 is a block diagram showing another embodiment of the multiband antenna switch circuit of the present invention.
FIG. 5 is a block diagram showing still another embodiment of the multiband antenna switch circuit of the present invention.
FIG. 6 is an equivalent circuit diagram of a Human Body Model tester that reproduces an electrostatic surge.
FIG. 7 is a diagram showing a waveform of an electrostatic surge voltage.
FIG. 8 is a diagram showing a frequency spectrum of an electrostatic surge waveform.
FIG. 9 is a diagram illustrating an example of a conventional electrostatic surge countermeasure circuit.
FIG. 10 is a diagram showing another example of a conventional electrostatic surge countermeasure circuit.
FIG. 11 is a diagram showing attenuation characteristics of a conventional electrostatic surge countermeasure circuit and the electrostatic surge countermeasure circuit of the present invention.
FIG. 12 is a diagram showing reflection characteristics of a conventional electrostatic surge countermeasure circuit and the electrostatic surge countermeasure circuit of the present invention.
FIG. 13 is a perspective view of a multi-band antenna switch laminated module composite part incorporating the electrostatic surge countermeasure circuit of the present invention.
FIG. 14 is an equivalent circuit diagram of a PIN diode switch having a built-in electrostatic surge countermeasure circuit according to the prior art.
FIG. 15 is an equivalent circuit diagram of an antenna switch circuit module having a built-in electrostatic surge countermeasure circuit according to the prior art.
FIG. 16 is an example of a block diagram of a triple-band antenna switch circuit according to the prior art.
FIG. 17 is another example of a block diagram of a triple band antenna switch circuit according to the prior art.
[Explanation of symbols]
ANT: antenna terminal P1: input terminal P2: output terminals TX, TX1, TX2: transmission terminals RX, RX1, RX2: reception terminals VC, VC1, VC2: control power supply terminals Vs: power supplies Dip, Dip1, electrostatic surge voltage application Dip2: Diplexer LPF1, LPF2: Low-pass filters SW, SW1, SW2: Switch circuits SAW, SAW1, SAW2, SAW3: SAW filters L, L1-L9: Transmission lines, inductors or choke coils C, C1-C11: Capacitors D, D1 D4: PIN diodes R, R1, R2: Resistance 1: Multilayer dielectric 2: SP3T GaAs FET switch 3: SAW filter 4: Chip inductor 5: Chip capacitor

Claims (6)

A high-pass filter having a high-pass filter circuit and a series resonant circuit between the input terminal and the output terminal,
The high-pass filter circuit allows an electrostatic surge to escape to the ground, and includes a first inductor connected between the input terminal and the ground, and a first inductor connected between the input terminal and the output terminal. The series resonance circuit includes a second inductor and a second capacitor connected between the output terminal and the ground, and has a resonance frequency between 100 MHz and 500 MHz.
Reflection characteristics S. W. R is 1.3 or less at 1 GHz to 2 GHz,
A high-pass filter that is excellent in attenuation at 300 MHz or less and is used for countermeasures against electrostatic surges. In the high-pass filter circuit according to claim 1, wherein between the series resonant circuit and said output terminal, a high-pass filter comprising the parallel resonant circuit comprising a third inductor and a third capacitor. High pass filter, characterized in that connecting the SAW filter at the output end of the high-pass filter circuit according to claim 1 or 2 wherein.   A switch circuit comprising a switch connected to the output end side of the high-pass filter circuit according to claim 1.   A switch circuit comprising a switch connected to the input end side of the high-pass filter circuit according to claim 1.   A communication apparatus using the high-pass filter circuit according to claim 1.

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