KR100886258B1 - Method and device for selecting between internal and external antennas - Google Patents

Abstract

In an RF front end having a plurality of signal paths that can be connected to an internal antenna or an external antenna, an antenna switch portion is used to select either the internal antenna or the external antenna. In the antenna switch section, two series switches are used to operate connected to the same connection point of each signal path. The two switches are individually connected to the two different antennas to select one of the two different antennas and route the signals in the signal path. In order to provide another separation between the signal paths, each signal path may be connected with a shunt switch close to the connection point. Only the shunt switch connected to the selected signal path operates in the open position and all other shunt switches operate in the closed position.

Description

Method and device for selecting between internal and external antennas

FIELD OF THE INVENTION The present invention relates generally to RF front end devices of mobile phones, and more particularly to switching devices of front end mobile phones.

When a mobile phone is operable in several different frequency bands, such as GSM and W-CDMA bands, the RF front-end of the mobile phone has a plurality of switches to select any one of the bands. For example, if a mobile phone can operate in multiple GSM bands and one W-CDMA band, as shown in FIG. 1A, the mobile phone has two antennas: one GSM antenna 10 and one W-. It has a CDMA antenna 12. The front end module 1 is an antenna switch 20 having a plurality of series switches 22, 24, 26, 28 that are connected to and operate on GSM signal paths 32, 34, 36, 38. In addition, GSM signals may be routed through the GSM antenna 10 via the common node 29. The front end module 1 also includes a duplexer 40 having a bandpass filter 42 and a bandpass filter 44 that operate in connection with the W-CDMA signal paths 52, 54. Allow CDMA signals to be routed through the W-CDMA antenna 12. For path selection purposes, each of the switches 22, 24, 26, 28 of the antenna switch 20 serves as a path selection component that should be operated in an "ON" state or an "OFF" state. The bandpass filters 42, 44 may also be considered as path selection components, but they do not have to operate in an “OFF” state for band rejection. Unlike shunt switches, the path selection components are each in series components, which are connected in series with other RF front end components, such as amplifiers and filters (not shown) that follow the same signal path. In fact, the multi-mode, multi-band RF front end is substantially the same as shown in FIG. 1B. The front end comprises a plurality of bandpass filters (such as filter 332), baluns (such as balun 432), matching elements (such as inductive element 836 and capacitive element 834) and phase It is typical to include shifters (such as shifters 725, 734, 752). The RF front end also includes a duplexer 920 with harmonic filters for GSM Tx. For GSM Tx-Rx switching, the actual implementation for each switching function has one or more series switching elements and one shunt element. The switching elements may be FETs such as CMOS devices, p-HEMTs such as GaAs devices, or the like. If diodes are used as switches, one or more 90 degree phase shifters are also used. As shown in FIG. 1B, two series diodes 526, 528, two shunt diodes 624, 626, and two phase-shifters 724, for GSM Tx-Rx switching. 734) is used. If FETs are used as switching elements, any one of the paths can be selected by biasing the appropriate series switch to " ON " as shown in FIG. 1C (second in this figure). Route is selected). In order to increase isolation with respect to the selected path, only the shunt switch of the selected path is "OFF" and all remaining shunt switches are "ON".

The antennas 10, 20 shown in FIG. 1A are referred to herein as internal antennas of a mobile phone. This is because they are commonly associated with mobile phones. In the example of FIG. 1A, antenna switch 20 is used to select signal paths from two different GSM bands. In many cases, an antenna switch should be used to select signal paths among four different GSM bands at 850, 900, 1800, and 1900 MHz.

When a mobile phone is used in connection with an external antenna, such as when the mobile phone is so configured that it can be used to send and receive signals via one or more automobile antennas, additional switches are needed. As shown in FIG. 2, two additional switches 62, 64 individually connected in series with the switches 22, 24, 26, 28 are connected to the internal antenna 10 and the external via a common node 29. It is used to select signal paths between the antennas 14. Similarly, two additional switches 66, 68, individually connected in series with the bandpass filters, are used to select the signal paths between the internal antenna 12 and the external antenna 14. Like the internal switches 22, 24, 26, 28, the additional switches 62, 64, 66, 68 are also path selection components capable of operating in the "ON" and "OFF" states, respectively. Thus, in the switching device shown in Fig. 2, regardless of which of the antennas 10, 14 are used for signal transmission and reception, the signal paths 32, 34, 36, 38 each select two serial paths. With components, each serial selection component can operate in an "ON" state and an "OFF" state. For example, if a path between the external antenna and the GSM Rx1 path is selected, the received signals may pass through two path selection components: switch 64 and switch 22 connected in series. Placing additional path selection components in the signal path results in additional losses. The losses are particularly problematic in the case of W-CDMA. It should be noted that the switches shown in FIGS. 1 and 2 are typically solid-state switches such as PIN diodes, GaAs pseudimorphic High Electron Mobility Transistors (GaAs p-HEMT), for example. The losses associated with these types of solid state switches are usually very serious. Mechanical switches can be used to reduce the losses, but the size of the mechanical switches makes their use impractical.

It is desirable and useful to provide a method and apparatus for selecting signal paths between internal and external antennas so as to prevent or minimize losses.

The present invention uses an antenna switch part, wherein two serial path selection components or switches are used to operate in connection with the same connection point of each signal path. The two series switches are individually connected to the two different antennas to select one of the two different antennas to route signals through the signal path. In fact, the two switches for each signal path are connected in parallel. In a mobile terminal with N signal paths, 2N series switches are used to select the signal paths as well as the antennas. However, if the frequency range difference between the two signal paths is so small that bandpass filters or phase shifters can be used for path selection, the number of series switches can be reduced.

Accordingly, a first aspect of the present invention provides an antenna switch for use in connection with an RF front-point of a communication device, wherein the front end of the communication device is provided with a plurality of frequencies via a first antenna or a second antenna. Having a plurality of signal paths for carrying signals of a band, the frequency bands include one or more GSM transmit frequency bands and one GSM receive frequency band. The antenna switch unit:

A plurality of first switching elements, each switching element having a first end and a second end, wherein the first switching elements electrically separate the first end from the second end. Operate in a closed position to electrically connect the first end with the second end, and the first end connected to the first antenna. A plurality of first switching elements, the plurality of first switching elements operating in connection with the second end connected to an individual signal path of one of the signal paths; And

As a plurality of second switching elements, each switching element has a first end and a second end, and the second switching elements can operate in an open position to electrically separate the first end from the second end and And may operate in a closed position to electrically connect the first end to the second end, wherein the first end is connected to the second antenna to operate, and the second end is one of the first switching elements. A closed position in which the first switching element or the second switching element connected to one of the plurality of signal paths comprises a plurality of second switching elements connected to and operated in a second stage of one individual first switching element In operation, the signals of the one signal path can be routed through the first antenna or the second antenna.

According to the invention, the frequency bands also comprise one other GSM transmit frequency band and one other GSM receive frequency band.

According to the invention, the front end further has another signal path for carrying signals of a code-division multiple access frequency band through either the second antenna or the third antenna. The antenna switch unit:

A third switching element having a first end and a second end, wherein the third switching element can operate in an open or closed position, the first end connected to the third antenna and operate And further comprising a third switching element operatively connected to said other signal path and said other signal path also operatively connected to a second end of an individual second switching element of one of said second switching elements.

According to the invention, said code-division multiple access frequency band comprises a W-CDMA frequency band.

According to the present invention, the antenna switch unit comprises: a first stage, each shunt switch being one or more shunt switches, connected to an individual signal path of one of the signal paths, and a second stage connected to circuit ground; Further comprising one or more shunt switches, each shunt switch capable of operating in a closed position or an open position, and if there is a shunt switch connected to said one signal path, said shunt switch operates in an open position.

Alternatively, the antenna switch portion has a first stage connected to each individual signal path of one of the signal paths, and a second end connected to circuit ground, each shunt switch being a plurality of shunt switches. The shunt switch further comprises a plurality of shunt switches operating in the closed position or the open position, the shunt switch connected to the one signal path operating in the open position and the shunt switch connected to each of the remaining signal paths in the closed position. Should work.

A second aspect of the present invention provides a method of selecting one of the signal paths at an RF front end of a communication device, the communication device comprising a first antenna and a second antenna, and wherein the signal paths comprise the first Used to transmit signals of a plurality of frequency bands through one antenna or the second antenna, the frequency bands comprising one or more GSM transmit frequency bands and one GSM receive frequency band. The method is:

Providing a plurality of first switching elements, each first switching element having a first end and a second end, wherein the first switching elements comprise the first end and the first end; May be operated in an open position to electrically separate from the second stage and may be operated in a closed position to electrically connect the first stage to the second stage, wherein the first stage is connected to the first antenna to operate Providing a plurality of first switching elements operatively coupled to the second stage and connected to an individual signal path of one of the signal paths;

Providing a plurality of second switching elements, each second switching element having a first end and a second end, wherein the second switching elements are open to electrically separate the first end from the second end. May be operated in a closed position to electrically connect the first end with the second end, the first end connected to the second antenna, and the second end being operated in the Providing a plurality of second switching elements operating in connection with a second end of an individual first switching element of one of the first switching elements; And

Causing one of the first switching element or the second switching element connected to the selected signal path to operate in the closed position to route signals of the selected signal path through the first antenna or the second antenna; Include.

According to the invention, the communication device further comprises a third antenna, the front end of which is another signal path for carrying signals of a code division multiple access frequency band through either the second antenna or the third antenna. Has The method is:

Providing a third switching element having a first end and a second end, wherein the third switching element is operable in an open or closed position, the first end is connected to the third antenna and operates Providing a third switching element in which said second stage is connected to and operating in said other signal path and said other signal path is also in operation in connection with a second stage of an individual second switching element of one of said second switching elements. Doing; And

Causing the third switching element to operate in the closed position to route signals of the other signal path through the third antenna.

According to the invention, the selected signal path is also used to carry signals of the code division multiple access frequency band, and also receives diversity by routing the signals of the code division multiple access frequency band through the first antenna. In order to achieve receive diversity, the first switching element connected to the selected signal path is operated in a closed state.

A third aspect of the invention is a communication device,

RF front-end;

An antenna switch part;

A first antenna connected to the RF front end through the antenna switch unit;

And a connector for causing a second antenna to be connected to and operate at the RF front end through the antenna switch unit, wherein the front end includes a plurality of frequencies through the first antenna or the second antenna. Having a plurality of signal paths for carrying signals of a band, said frequency bands comprising at least one GSM transmit frequency band and one GSM receive frequency band, and said antenna switch section being:

As a plurality of first switching elements, each switching element has a first end and a second end, and the first switching elements can operate in an open position to electrically separate the first end from the second end and And operate in a closed state to electrically connect the first end to the second end, wherein the first end is connected to the first antenna to operate, and the second end is connected to one of the signal paths. A plurality of first switching elements operatively coupled to an individual signal path; And

As a plurality of second switching elements, each switching element has a first end and a second end, and the second switching elements can operate in an open position to electrically separate the first end from the second end and And may operate in a closed state to electrically connect the first stage to the second stage, wherein the first stage is connected to the second antenna to operate, and the second stage is one of the first switching elements. A first switching element or a second switching element connected to one of the plurality of signal paths is closed, including a plurality of second switching elements connected to and operated at a second end of one individual first switching element. When operating in position, the signals in the one signal path can be routed through the first antenna or the second antenna.

According to the invention, the frequency bands also comprise one other GSM transmit frequency band and one other GSM receive frequency band.

According to the present invention, the communication device further comprises a third antenna connected to the RF front end via the antenna switch unit, wherein the front end is code-division multiplexed through either the second antenna or the third antenna. It further has another signal path for carrying signals in the access frequency band, and the antenna switch unit:

A third switching element having a first end and a second end, wherein the third switching element can operate in an open or closed position, the first end connected to the third antenna and operate And a third switching element, wherein the stage is connected to and operate in connection with the other signal path, and wherein the other signal path is also connected to and operated in a second stage of the individual second switching element of one of the second switching elements.

The communication device may be a mobile terminal or the like.

In the following, the invention will be clear by reading the descriptions described in connection with FIGS. 3A-7.

Is a schematic representation of a communication device having two internal antennas as a simplified prior art communication device.

FIG. 1B is a circuit diagram of an RF front end for a communication device having two internal antennas as an RF front end of an actual prior art.

1C is a schematic representation of a FET based SP4T antenna switch.

FIG. 2 is a schematic representation of a switch device of the prior art for selecting one antenna among internal and external antennas.

3a is a schematic representation of a switch arrangement according to the invention for selecting one antenna from internal and external antennas.

3B is a schematic diagram illustrating how the signal path is connected to the GSM antenna when there is no external antenna.

3C is a schematic diagram illustrating how the signal path is connected to the GSM antenna when there is an external antenna.

4 is a schematic diagram illustrating shunt switches used to improve performance.

5 is a diagram illustrating in schematic representation a quad-band GSM + WCDMA front end operating in conjunction with an antenna switch in accordance with the present invention.

FIG. 6 is a diagram illustrating in schematic representation W-CDMA Rx added to a quad-band GSM + WCDMA front end for MIMO reception.

7 is a schematic diagram illustrating a communication device having an antenna switch unit according to the present invention.

The invention uses a pair of switching elements corresponding to an SP2T switch for connection with each transmit path and each receive path, but transmit and receive path pairs through bandpass filters and phase shifters. The exception is when a pair of paths can be selected. In the latter case, the transmit and receive path pairs may share an SP2T switch. One of the switching elements of each SP2T switch device is connected to an internal antenna and the other to an external antenna. As shown in FIG. 3A, in addition to the two internal antennas 10, 12, an external antenna 14 is also used for transmitting and receiving signals. To select one of the external and internal antennas, two series switches 121, 122 are connected in parallel to the signal path 32. Similarly, series switch pairs 123, 124, 125, 126, and 127, 128 are connected in parallel to one of the signal paths 34, 36, 38, respectively. The switching pairs 131, 132 are connected to the duplexer 40. As in the prior art switch arrangement shown in FIG. 1A, the switches 121, 123, 125, 126 are connected to the internal GSM antenna 10 via a common node 29. The switch 131 is connected to the internal W-CDMA antenna 12. Since only one external antenna 14 can be used for transmission and reception, all other switches are connected to the external antenna 14 via a common node 129. The external antenna 14 is used for both GSM mode and W-CDMA mode. As can be seen in Figures 1a and 3a, the difference between the prior art front end module 1 and the front end module 100 according to the present invention is the antenna switch unit 20 and the antenna switch unit 120. Like the front end module 1 of the prior art, the internal antenna 10 is usually associated with a mobile phone and already attached to a common node. Similarly, the internal antenna 12 is already attached to the antenna switch unit 120. However, the external antenna 14 does not accompany the mobile phone. The external antenna 14 can be, for example, an automobile antenna. Thus, the external antenna 14 is typically required to be connected separately to the mobile phone. For example, the mobile phone can have a connector 19 that operates in connection with the common node 129, so that an external antenna can be connected to the mobile phone if necessary.

When the external antenna is not connected to the mobile phone, the SP2T switch pairs (121, 122), (123, 124), (125, 126), (127, 128), (131, 132), respectively, One of the switches of the pair is "ON", but other switches of the same pair may be so biased to be "OFF". As shown in FIG. 3B, the switches 121, 123, 126, 127, 131 are biased to "OFF" while the switches 122, 124, 125, 128, 132 are biased to "ON". Select the GSM Tx1 path. As such, the GSM transmission path 36 is connected to the internal antenna 10 and operates. Signal paths 32, 34, 38, 52, and 54 are not selected even if switches 122, 124, 125, 128, and 132 are biased "ON". This is because the external antenna 14 is not connected. However, when the external antenna 14 is connected to the antenna switch unit 120 to operate, only the switch 125 is “ON” in order for the GSM transmission path 36 to be connected to the internal antenna 10 to operate. do. As shown in FIG. 3C, all other switches are turned “OFF”. If instead the external antenna 14 is selected to route the signals of the GSM transmission path, only the switch 126 is "ON" and all other switches are "OFF". It should be noted that the path selection shown in FIG. 3B is possible if the impedance seen at node 19 appears to be an open circuit. In practice, the switch module needs to be physically very close to the external antenna connector. Alternatively, proper phase shifting between the antenna connector and the switch module 120 needs to be provided. The benefit of these features is that it improves the isolation between the selected and unselected paths.

It should be noted that, depending on system requirements, switches for use in connection with the path selection shown in FIGS. 3A and 3B and the like may be used as solid-state switches or even micro-electromechanical; MEM) switch. Solid state switches, such as CMOS based (eg CMOS on SOI) switches, are good candidates for path selection. Unlike GaAs devices, CMOS devices do not require negative bias. Unlike PIN diodes that require physically large biasing elements to separate RF from DC, CMOS does not require large biasing elements. When the number of switch paths is large, the current consumption in PIN diodes can be very large.

The switching device shown in FIGS. 3A and 3B can be enhanced by adding shunt elements to the signal paths. For example, the transmit and receive ports may each be connected to the shunt switch shown in FIG. 4. As shown, shunt switches 232, 234, 236, 238, 240 are individually connected to signal paths 32, 34, 36, 38 and duplexer 40. The shunt switches improve the separation between selected and unselected paths.

At the quad-band GSM + W-CDMA front end, additional filters are needed and additional matching phase shifting elements may be needed. As shown in FIG. 5, the GSM Rx1 signal path 32 is used for both GSM Rx (869-894 MHz) and GSM Rx (925-960 MHz). Phase shifting element 81 and bandpass filter 71 are connected in series to port 61, and phase shifting element 82 and bandpass filter 72 are connected in series to port 62. . Similarly, phase shifting element 83 and bandpass filter 73 are connected in series to port 63, and phase shifting element 84 and bandpass filter 74 are serially connected to port 64. Connected. Lowpass filter 76 is used for frequency filtering at GSM Tx1 port 66. Lowpass filter 78 is used for frequency filtering at GSM Tx2 port 68. In FIG. 5, two low band GSM Rx filters are matched with one switch node (GSM Rx1) and thus matched with phase shifting elements. Similarly, two high band GSM Rx filters are matched to the other switch node (GSM Rx2). This makes it possible to reduce the total number of switches. However, if necessary, it is possible to have a dedicated Rx switch for each band. If the frequency interval is large enough, it is possible to match three or more filters with a single node.

Additionally, the W-CDMA Rx path may be coupled to the GSM Rx path for MIMO reception via other internal antennas. As shown in FIG. 6, a phase shift element 86 and a bandpass filter 46 are connected between the GSM Rx1 path 32 and the W-CDMA (2110-2170 MHz) Rx port.

As illustrated in FIGS. 3A-6, switching between internal and external antennas can be achieved without loss from losses due to additional series switching elements of the GSM signal paths. In each of the multi-band RF front-end devices, including dual-band GSM and quad-band GSM in combination with W-CDMA or MIMO W-CDMA reception, each to facilitate the selection of one antenna among the internal and external antennas. The signal path has only one series switch. When a mobile phone is used as a stand-alone handset, the switching device according to the invention is substantially the same as the prior art device except for the W-CDMA paths.

In short, the present invention provides an antenna switch for use in connection with an RF front end of a communication device. For example, referring to FIG. 3A, the front end 100 is configured to transmit signals of a plurality of frequency bands GSM Rx1, Rx2, Tx1, and Tx2 through the first antenna 10 or the second antenna 14. Has a signal path of 32, 34, 36, 38, wherein the frequency interval between the GSM transmission frequency bands or the frequency interval between the GSM reception frequency bands is 300 MHz or more, and the antenna switch unit;

A plurality of first switching elements 121, 123, 125, and 127, each switching element having a first stage and a second stage, each first switching element electrically coupling the first stage to the second stage. May be operated in an open position for disconnection and may be operated in a closed position for electrically connecting the first end to the second end, and the first end may be connected to the first antenna 10 for operation. A plurality of first switching elements operatively connected to the second end of the signal path in one of the signal paths (32, 34, 36, 38); And

A plurality of second switching elements 122, 124, 126, 128, each switching element having a first stage and a second stage, each second switching element electrically coupling the first stage to the second stage. May be operated in an open position for disconnection and may be operated in a closed position for electrically connecting the first end to the second end, and the first end may be connected to the second antenna 14 for operation. And the second stage includes a plurality of second switching elements that are connected to and operate in connection with a second end of one individual first switching element among the first switching elements 121, 123, 125, and 127. When the first switching element or the second switching element connected to one of the plurality of signal paths operates in the closed position, the signals of the one signal path are routed through the first antenna or the second antenna. To be do. In FIG. 3C, when the first switch 125 operates in the “ON” state or the closed position, the signals of the signal path 36 are routed through the first antenna 10. However, instead of the first switch 125, if the second switch 126 operates in the "ON" state, the signals of the signal path 36 are routed through the second antenna 14. To provide different separation between signal paths, each signal path may be connected to a shunt switch close to the port end.

It should be noted that the embodiments shown in FIGS. 3A-6 are mainly used to demonstrate how the antenna switch of the present invention can be applied to an RF front end having a GSM band and a WCDMA band combination. However, the present invention can also be applied to, for example, a GSM band and a CDMA band combination, a GSM band and a multiple CDMA band, or a multiple WCDMA band combination. In addition, the MIMO path of FIG. 6 may be used for supplemental wireless applications, such as WLAN, Bluetooth, and GPS.

The switching device shown in FIGS. 3A-6 may be used in the mobile terminal 500 or other communication devices shown in FIG. 7. As shown in FIG. 7, the mobile terminal 500 has a first internal antenna 10 and a second internal antenna 12 that are connected to the antenna switch 120 and operate. The mobile terminal 500 also includes a GSM transceiver 510 and a CDMA (or W-CDMA) transceiver 550. In order to selectively transmit signals of GSM frequency bands to the first internal antenna 10, the GSM transceiver 510 has a plurality of signal paths that operate in connection with the antenna switch 120. Similarly, in order to selectively transmit signals of code-division multiple access frequency bands to the second internal antenna 12, the transceiver 550 is connected to the antenna switch 120 to operate a plurality of signal paths. Have The mobile terminal 500 further includes a connector 19 to allow an external antenna (not shown) to be connected to the antenna switch unit 120 to operate. When a second antenna is connected to the connector 19, one or more signal paths of the transceivers 510, 550 are routed through either the antenna switch 120 to either internal or external antennas. Can be.

While the invention has been described with reference to one or more embodiments thereof, the foregoing and other modifications, omissions and variations in form and detail of the invention are intended to limit the scope of the invention. It will be apparent to those skilled in the art that this may be accomplished without departing.

Claims (19)

In an antenna switch part for use in connection with an RF front-end of a communication device, the front end is for transmitting signals of a plurality of frequency bands through a first antenna or a second antenna. A plurality of signal paths, the frequency bands including one or more GSM transmission frequency bands and one GSM reception frequency band, wherein the antenna switch unit comprises: A plurality of first switching elements configured to be connected to the first antenna; And A plurality of second switching elements configured to be connected to the second antenna, Each said signal path is connected to said first antenna or disconnected from said first antenna via a different element of said first switching elements, and is connected to said second antenna via said different element of said second switching elements or 2, the antenna switch unit characterized in that disconnected from the antenna. The method of claim 1, And the frequency bands further comprise one other GSM transmission frequency band and one other GSM reception frequency band. The method of claim 1, The front end further comprises an additional signal path for carrying signals of a code-division multiple access frequency band, the additional signal path being routed through another one of the second switching elements; Connected to a second antenna or disconnected from the second antenna, connected to a third antenna through a third switching element, or disconnected from the third antenna, such that the signal of the code division multiple access frequency band is And an antenna switch unit, which can be transmitted through the third antenna. The method of claim 3, And the code-division multiple access frequency band includes a W-CDMA frequency band. The method of claim 1, And each signal path is connected to a circuit ground via a shunt switch when each signal path is disconnected from both the first antenna and the second antenna. delete The method of claim 1, And the communication device comprises a mobile terminal. A method for selecting one signal path from among a plurality of signal paths of an RF front-end of a communication device, The communication device comprises a first antenna and a second antenna, wherein the signal paths are used to carry signals of a plurality of frequency bands through the first antenna or the second antenna, the frequency bands being one or more GSM transmissions A signal path selection method comprising a frequency band and one GSM reception frequency band, Providing a plurality of first switching elements configured to be connected to the first antenna, each first switching element being operable in a closed position or an open position; Providing a plurality of second switching elements configured to be connected to the second antenna, each second switching element being operable in a closed position or an open position; Connecting each of the signal paths to a first antenna through a different one of the first switching elements and to the second antenna through a different one of the second switching elements; And Causing one of the first switching element or the second switching element connected to the selected signal path to operate in the closed position to route the signals of the selected signal path through the first antenna or the second antenna; Signal path selection method comprising a. The method of claim 8, The communication device further comprises a third antenna, the front end further comprising an additional signal path for carrying signals in a code division multiple access frequency band through either the second antenna or the third antenna, The additional signal path is connected to or disconnected from the second antenna via another one of the second switching elements, The signal path selection method, A third switching element is connected between the additional signal path and the third antenna such that the additional signal path is connected to the third antenna to signal through a third or second antenna code-division multiple access frequency band; Signal path selection method characterized in that it can be delivered. The method of claim 9, And wherein said selected signal path is also used for conveying signals of said code-division multiple access frequency band through said first antenna in order to achieve receive diversity. RF shear; And Communication device comprising an antenna switch according to claim 1. The method of claim 11, And said frequency bands also comprise one other GSM transmit frequency band and one other GSM receive frequency band. The method of claim 12, And said GSM frequency band and said other GSM frequency band comprise 1GSM Rx, 2GSM Rx, 1GSM Tx, and 2GSM Tx. The method of claim 11, The front end has an additional signal path for carrying signals in the code division multiple access frequency band, the additional signal path being connected to the second antenna through another one of the second switching elements or the second antenna Disconnected from, and connected to or disconnected from the third antenna via a third switching element. The method of claim 14, And said code-division multiple access frequency band comprises a W-CDMA frequency band. The method of claim 15, And wherein the W-CDMA frequency band comprises an Rx frequency band substantially between 2110 MHz and 2170 MHz, and a Tx frequency band substantially between 1920 MHz and 1980 MHz. The method of claim 11, And each of the signal paths is connected to circuit ground through a shunt switch when each of the signal paths is disconnected from the first antenna and the second antenna. delete The method of claim 11, And said communication device comprises a mobile terminal.

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