Antenna switching circuits for radio telephones

Claim 2

Antenna switching circuitry as set forth in claim 1, wherein the lengths of said transmission lines are as follows: L1 = L4 = I/2 for the first frequency band; and L2 = L3 = I/2 for the second frequency band.

Claim 3

Antenna switching circuitry as set forth in claim 1, wherein the first frequency band includes a frequency of about 800 MHz, and wherein the second frequency band includes a frequency of about 1900 MHz.

Claim 4

Antenna switching circuitry as set forth in claim 1, wherein the first antenna port is coupled to an integral antenna, and wherein said second antenna port is for coupling to an external antenna.

Claim 5

Antenna switching circuitry as set forth in claim 1, wherein said first transceiver transmits and receives a duplex frequency modulated (FM) RF signal, and wherein said second transceiver transmits and receives a time division, multiple access (TDMA) phase modulated RF signal.

Claim 6

Antenna switching circuitry as set forth in claim 1, wherein an antenna impedance for both said first and said second transceivers is about 50 ohms.

Claim 7

Antenna switching circuitry as set forth in claim 1, wherein said input/output port of said first transceiver is coupled to a first duplexer, and wherein said input/output port of said second transceiver is coupled to a second duplexer.

Claim 8

Antenna switching circuitry as set forth in claim 1, wherein said input/output port of said first transceiver is coupled to a duplexer, and wherein said input/output port of said second transceiver is coupled to a transmit/receive switch.

Claim 9

Antenna switching circuitry for use in a radio telephone of a type that includes a first transceiver operable in a first frequency band and a second transceiver operable in a second frequency band, the radio telephone further comprising a first antenna port and a second antenna port, said antenna switching circuitry comprising: a first pair of transmission lines (L1 and L2) each having a first node coupled to said first antenna port, a second node of L1 being switchably coupled to an input/output port of said first transceiver and a second node of L2 being switchably coupled to an input/output node of said second transceiver; and a second pair of transmission lines (L3 and L4) each having a first node coupled to said second antenna port, a second node of L3 being switchably coupled to said input/output port of said first transceiver and a second node of L4 being switchably coupled to said input/output node of said second transceiver; wherein when the second node of L1 is coupled to said input/output port of said first transceiver, the second node of both L2 and L3 is open circuited and the second node of L4 is coupled to said input/output port of said second transceiver; and wherein when the second node of L2 is coupled to said input/output port of said second transceiver, the second node of both L1 and L4 is open circuited and the second node of L3 is coupled to said input/output port of said first transceiver.

Claim 10

Antenna switching circuitry as set forth in claim 9, wherein the lengths of said transmission lines are as follows: L2 = L4 = I/2 for the first frequency band; and L1 = L3 = I/2 for the second frequency band.

Claim 11

Antenna switching circuitry as set forth in claim 9, wherein the first frequency band includes a frequency of about 800 MHz, and wherein the second frequency band includes a frequency of about 1900 MHz.

Claim 12

Antenna switching circuitry as set forth in claim 9, wherein the first antenna port is coupled to an integral antenna, and wherein said second antenna port is for coupling to an external antenna.

Claim 13

Antenna switching circuitry as set forth in claim 9, wherein said first transceiver transmits and receives a duplex frequency modulated (FM) RF signal, and wherein said second transceiver transmits and receives a time division, multiple access (TDMA) phase modulated RF signal.

Claim 14

Antenna switching circuitry as set forth in claim 9, wherein an antenna impedance for both said first and said second transceivers is about 50 ohms.

Claim 15

Antenna switching circuitry as set forth in claim 9, wherein said input/output port of said first transceiver is coupled to a first duplexer, and wherein said input/output port of said second transceiver is coupled to a second duplexer.

Claim 16

Antenna switching circuitry as set forth in claim 9, wherein said input/output port of said first transceiver is coupled to a duplexer, and wherein said input/output port of said second transceiver is coupled to a transmit/receive switch.

Claim 17

Antenna switching circuitry as set forth in claim 9, wherein said second node of L1 and said second node of L3 are coupled through a first switch to said input/output port of said first transceiver, wherein said second node of L2 and said second node of L4 are coupled through a second switch to said input/output port of said second transceiver, wherein said first switch is selected to minimize an insertion loss for frequencies within said first frequency band, and wherein said second switch is selected to minimize an insertion loss for frequencies within said second frequency band.

Claim 18

Antenna switching circuitry for use in a radio telephone of a type that includes a transmitter operable in a first frequency band when transmitting and a receiver operable in a second frequency band when receiving, the radio telephone further comprising a first antenna port and a second antenna port, said antenna switching circuitry comprising: a pair of transmission lines (L1 and L2) each having a first node and a second node, a first node of L2 being coupled to an input port of said receiver and a first node of L1 being coupled to an output port of said transmitter; a first switch having a first switching state for coupling said input port of said receiver to the first antenna port, the first switch further having a second switching state for coupling said output port of said transmitter to the first antenna port through the second mode of L1, wherein in the first switching state of the first switch the second node of L1 is open-circuited; and a second switch operated in phase with the first switch and having a first switching state for coupling said output port of said transmitter to the second antenna port, said second switch further having a second switching state for coupling said input port of said receiver to the second antenna port through the second node of L2, wherein in the first switching state of the second switch the second node of L2 is open-circuited.

Claim 19

Antenna switching circuitry as set forth in claim 18, wherein the lengths of said transmission lines are as follows: L1 = I/2 for the first frequency band; and L2 = I/2 for the second frequency band.

Claim 20

Antenna switching circuitry as set forth in claim 18, wherein the first antenna port is coupled to an integral antenna, and wherein said second antenna port is for coupling to an external antenna.

Claim 21

Antenna switching circuitry for use in a dual band radio telephone, comprising: a first transmitter and a first receiver operable in a first frequency band when transmitting and receiving; a second transmitter and second receiver operable in a second frequency band when transmitting and receiving; a first antenna port; a second antenna port; a pair of transmission lines (L1 and L2) each having a first node and a second node, wherein said second node of L1 is coupled to said first antenna port and said second node of L2 is coupled to said second antenna port; a first switch having a first switching state for coupling an input port of said first receiver to said first antenna port, the first switch further having a second switching state for coupling said input port of said first receiver to said first node of L2 and through L2 to said second antenna port; a second switch having a first switching state for coupling an output port of said first transmitter to said first antenna port, the second switch further having a second switching state for coupling said output port of said first transmitter to said first node of L2 and through L2 to said second antenna port; a third switch having a first switching state for coupling an input port of said second receiver to said first node of L1 and through L1 to said first antenna port, said third switch further having a second switching state for coupling said input port of said second receiver to said second antenna port; and a fourth switch having a first switching state for coupling an output port of said second transmitter to said first node of L1 and through L1 to said first antenna port, said fourth switch further having a second switching state for coupling said output port of said second transmitter to said second antenna port; wherein said first, second, third and fourth switches are controlled such that at any given time during the operation of said radio telephone three of said switches are in one of said first or second switching states, and a remaining one of said switches is in an opposite switching state.

Claim 22

Antenna switching circuitry as set forth in claim 21, wherein said first band of frequencies is approximately twice the second band of frequencies.

Claim 23

Antenna switching circuitry as set forth in claim 21, wherein the lengths of L1 and L2 are as follows: L1 = L2 = I/2 for the first frequency band; and L1 = L2 = 2(I/2) for the second frequency band.

Claim 24

Antenna switching circuitry for use in a dual band radio telephone, comprising: a first transmitter and a first receiver operable in a first frequency band when transmitting and receiving; a second transmitter and second receiver operable in a second frequency band when transmitting and receiving; a first antenna port; a second antenna port; eight transmission lines (L1-L8) each having a first node and a second node, wherein said second node of L1, L3, L5 and L7 is coupled to said first antenna port and said second node of L2, L4, L6, and L8 is coupled to said second antenna port; a first switch having a first switching state for coupling an input port of said first receiver to said first node of L1 and through L1 to said first antenna port, the first switch further having a second switching state for coupling said input port of said first receiver to said first node of L2 and through L2 to said second antenna port; a second switch having a first switching state for coupling an output port of said first transmitter to said first node of L3 and through L3 to said first antenna port, the second switch further having a second switching state for coupling said output port of said first transmitter to said first node of L4 and through L4 to said second antenna port; a third switch having a first switching state for coupling an input port of said second receiver to said first node of L5 and through L5 to said first antenna port, said third switch further having a second switching state for coupling said input port of said second receiver to said first node of L6 and through L6 to said second antenna port; and a fourth switch having a first switching state for coupling an output port of said second transmitter to said first node of L7 and through L7 to said first antenna port, said fourth switch further having a second switching state for coupling said output port of said second transmitter to said first node of L8 and through L8 to said second antenna port; wherein said first, second, third and fourth switches are controlled such that at any given time during the operation of said radio telephone three of said switches are in one of said first or second switching states, and a remaining one is in an opposite switching state.

Claim 25

Antenna switching circuitry as set forth in claim 24, wherein the lengths of L1-L8 are as follows: L1-L4 = I/2 for the second frequency band; and L5-L8 = I/2 for the first frequency band.