Method and device for selecting between internal and external antennas

• US 20060079275A1
• Filed: 06/18/2004
• Published: 04/13/2006
• Est. Priority Date: 06/18/2004
• Status: Active Grant

• Current Assignee: Nokia Technologies Oy (Nokia Corporation)
• Original Assignee: Nokia Corporation
• Inventors: Ella, Juha, Kojola, Ilkka Tarmo
• Granted Patent: US 7,251,499 B2
• Time in Patent Office: Days
• US Class Current: 455/553.100
• CPC Class Codes: H04B 1/006 using switches for selecting the desired band H04B1/0057 takes precedence

Abstract

In an RF front-end having a plurality of signal paths connectable to an internal antenna or an external antenna, an antenna switch part is used to select either the internal or the external antenna. In the antenna switch part, two series switches are used to operatively connect to the same connection point in each signal path. These two series switches are separately connected to two different antennas for selecting one of the antennas in order to route the signals in that signal path. For providing further isolation between signal paths, each signal path can be connected to a shunt switch near the connection point. Only the shunt switch connected to the selected signal path is operated in an open position, all the other shunt switches are operated in a closed position.

Claims

1. An antenna switch part for use in conjunction with an RF front-end of a communications device, wherein the front-end has a plurality of signal paths for conveying signals in a plurality of frequency bands through a first antenna or a second antenna, the frequency bands including at least one GSM transmit frequency band and one GSM receive frequency band, said antenna switch part comprising:

a plurality of first switching elements, each switching element having a first end a second end, the first switching elements operable in an open position for electrically isolating the first end from the second end and in a closed position for electrically connecting the first end to the second end, the first end operatively connected to the first antenna, the second end operatively connected to a different one of the signal paths; and

a plurality of second switching elements, each switching element having a first end and a second end, the second switching elements operable in an open position for electrically isolating the first end from the second end and in a closed position for electrically connecting the first end and the second end, the first end operatively connected to the second antenna, the second end operatively connected to the second end of a different one of the first switching elements, so that the signals in one of the plurality of signal paths can be routed through the first or the second antenna when the first or the second switching element connected to said one signal path is operated in the closed position.

2. The antenna switch part of claim 1, wherein the frequency bands also include one further GSM transmit frequency band and one further GSM receive frequency band.

3. The antenna switch part of claim 1, wherein the front-end further has a further signal path for conveying signals in a code-division multiple access frequency band through either the second antenna or a third antenna, said antenna switch part further comprising:

a third switching element having a first end and a second end, the third switching element operable in an open position or a closed position, the first end operatively connected to the third antenna and the second end operatively connected to the further signal path, wherein the further signal path is also operatively connected to the second end of a different one of the second switching elements.

4. The antenna switch of claim 3, wherein the code-division multiple access frequency band comprises a W-CDMA frequency band.

5. The antenna switch part of claim 1 further comprising one or more shunt switches, each shunt switch having a first end connected a different one of the signal paths, and a second end connected to a circuit ground, each shunt switch operable in a closed position or in an open position, wherein the shunt switch, if any, connected to said one signal path is operated in the open position.

6. The antenna switch part of claim 1 further comprising a plurality shunt switches, each shunt switch having a first end connected a different one of the signal paths, and a second end connected to a circuit ground, each shunt switch operable in a closed position or in an open position, wherein the shunt switch connected to said one signal path is operated in the open position and the shunt switch connected to each of the other signal paths is operated in the closed position.

7. The antenna switch part of claim 1, wherein the communications device comprises a mobile terminal.

8. A method for selecting a signal path among a plurality of signal paths in an RF front-end of a communications device, wherein the communications device comprises a first antenna and a second antenna, and wherein the signal paths are used to convey signals in a plurality of frequency bands through the first antenna or the second antenna, the frequency bands including at least one GSM transmit frequency band and one GSM receive frequency band, said method comprising:

providing a plurality of first switching elements, each first switching element having a first end a second end, the first switching elements operable in an open position for electrically isolating the first end from the second end and in a closed position for electrically connecting the first end to the second end, the first end operatively connected to the first antenna, the second end operatively connected to a different one of the signal paths;

providing a plurality of second switching elements, each second switching element having a first end and a second end, the second switching elements operable in an open position for electrically isolating the first end from the second end and in a closed position for electrically connecting the first end and the second end, the first end operatively connected to the second antenna, the second end operatively connected to the second end of a different one of the first switching elements; and

causing either the first or the second switching element connected to the selected signal path to operate in the closed position for routing the signals in the selected signal path through the first antenna or the second antenna.

9. The method of claim 8, wherein the communications device further comprises a third antenna, and the front-end further has a further signal path for conveying signals in a code-division multiple access frequency band through either the second antenna or the third antenna, said method further comprising:

providing a third switching element having a first end and a second end, the third switching element operable in an open position or in a closed position, the first end operatively connected to the third antenna and the second end operatively connected to the further signal path, wherein the further signal path is also operatively connected to the second end of a different one of the second switching elements; and

causing the third switching element to operate in the closed position for routing the signals in the further signal path through the third antenna, if so desired.

10. The method of claim 9, wherein the selected signal path is also used for conveying signals in the code-division multiple access frequency band, and wherein the first switching element connected to the selected signal path is caused to operate in the closed position so as to route the signals in the code-division multiple access frequency band also through the first antenna to achieve receive diversity.

11. A communications device, comprising:

an RF front-end;

an antenna switch part;

a first antenna operatively connected to the RF front-end through the antenna switch part;

a connector to allow a second antenna to operatively connected to the RF front-end through the antenna switch part;

wherein the front-end has a plurality of signal paths for conveying signals in a plurality of frequency bands through the first antenna or the second antenna, the frequency bands including at least one GSM transmit frequency band and one GSM receive frequency band, and wherein the antenna switch part comprises;

a plurality of first switching elements, each switching element having a first end a second end, the first switching elements operable in an open position for electrically isolating the first end from the second end and in a closed position for electrically connecting the first end to the second end, the first end operatively connected to the first antenna, the second end operatively connected to a different one of the signal paths; and

a plurality of second switching elements, each switching element having a first end and a second end, the second switching elements operable in an open position for electrically isolating the first end from the second end and in a closed position for electrically connecting the first end and the second end, the first end operatively connected to the second antenna, the second end operatively connected to the second end of a different one of the first switching elements, so that the signals in one of the plurality of signal paths can be routed through the first or the second antenna when the first or the second switching element connected to said one signal path is operated in the closed position.

12. The communications device of claim 11, wherein the frequency bands also include one further GSM transmit frequency band and one further GSM receive frequency band.

13. The communications device of claim 12, wherein the GSM and further GSM frequency bands include 1 GSM Rx, 2GSM Rx, 1 GSM Tx and 2GSM Tx.

14. The communications device of claim 11, further comprising a third antenna operatively connected to the RF front-end through the antenna switch part, wherein the front-end further has a further signal path for conveying signals in a code-division multiple access frequency band through either the second antenna or a third antenna, and wherein the antenna switch part further comprises:

a third switching element having a first end and a second end, the third switching element operable in an open position or a closed position, the first end operatively connected to the third antenna and the second end operatively connected to the further signal path, wherein the further signal path is also operatively connected to the second end of a different one of the second switching elements.

15. The communications device of claim 14, wherein the code-division multiple access frequency band comprises a W-CDMA frequency band.

16. The communications device of claim 15, wherein the W-CDMA frequency band includes a Rx frequency band substantially between 2110 to 2170 MHz, and a Tx frequency band substantially between 1920-1980 MHz.

17. The communications device of claim 11, wherein the antenna switch part further comprises one or more shunt switches, each shunt switch having a first end connected a different one of the signal paths, and a second end connected to a circuit ground, each shunt switch operable in a closed position or in an open position, and wherein the shunt switch, if any, connected to said one signal path is operated in the open position.

18. The communications device of claim 11, wherein the antenna switch part further comprises a plurality shunt switches, each shunt switch having a first end connected a different one of the signal paths, and a second end connected to a circuit ground, each shunt switch operable in a closed position or in an open position, and wherein the shunt switch connected to said one signal path is operated in the open position and the shunt switch connected to each of the other signal paths is operated in the closed position.

19. The communications device of claim 11, comprising a mobile terminal.