Telecommunications – Transmitter and receiver at same station – With transmitter-receiver switching or interaction prevention
Reexamination Certificate
1998-01-26
2003-01-21
Kincaid, Lester G. (Department: 2685)
Telecommunications
Transmitter and receiver at same station
With transmitter-receiver switching or interaction prevention
C455S553100
Reexamination Certificate
active
06510310
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to dual mode communication systems. More particularly, the present invention relates to a dual band radio frequency (RF) phone architecture which requires only a single transmit-receive switch.
BACKGROUND OF INVENTION
Dual mode or dual band wireless telephones can operate in two different communication bands, such as, a global system for mobile (GSM) communication band or a digital communication service (DCS) communications band. The dual mode telephone or hand set typically includes a switch or control circuit for selecting operation in either the GSM band or DCS band.
The GSM band is between 890 and 960 megahertz (MHz), and the DCS band is between 1,710 and 1,880 MHz. A dual mode telephone operating in the GSM band transmits signals in the 890-915 MHz band and receives signals in the 935-960 MHz band. A dual mode telephone operating in the DCS band transmits signals in the 1,710-1,785 MHz band and receives signals in the 1,805-1,880 MHz band.
Conventional GSM/DCS dual mode phone architectures utilize separate transmit-receive switches for each band. With reference to
FIG. 1
, a conventional dual mode phone system
10
can include a GSM transmit circuit
12
A, a DCS transmit circuit
12
B, a GSM receive circuit
14
A, a DCS receive circuit
14
B, a GSM transmit-receive switch
16
A, a DCS transmit-receive switch
16
B, a diplexer
18
, and an antenna
22
. GSM transmit circuit
12
A includes a GSM power amplifier
24
A, and DCS transmit circuit
12
B includes a DCS power amplifier
24
B. GSM receive circuit
14
A includes a mixer
32
A and a GSM filter
34
A, and DCS receive circuit
14
B includes a DCS filter
34
B and a mixer
32
B.
In operation, system
10
receives and transmits GSM band signals on GSM path
40
A and receives and transmits DCS signals on DCS path
40
B. Paths
40
A and
40
B are in communication with antenna
22
via diplexer
18
. Switches
16
A and
16
B receive transmit signals at an input
42
and provide the transmit signals to a diplexer interface
44
. Switches
16
A and
16
B receive signals at diplexer interface
44
and provide the receive signals to a receive output
46
.
Diplexer
18
also allows the simultaneous use of antenna
22
by both GSM and DCS switches
16
A and
16
B. Diplexer
18
separates GSM signals from DCS signals received from antenna
22
and provides the appropriate signals to paths
40
A and
40
B. Additionally, diplexer
18
isolates GSM signals on path
40
A from DCS signals on path
40
B and DCS signals on path
40
B from GSM signals on path
40
A.
Diplexer
18
can be a filter device having a low pass path coupled to path
40
A and a high pass path coupled to path
40
B. The high pass path and the low pass path preferably divide the frequency spectrum into two separate frequency bands, such as, the DCS band and the GSM band.
Transmit input
42
of switch
16
A is coupled to power amplifier
24
A in transmit circuit
12
A. Similarly, transmit input
42
of switch
16
B is coupled to power amplifier
24
B of transmit circuit
12
B. Receive output
46
of switch
16
A is coupled to filter
34
A in receive circuit
14
A. Similarly, receive output
46
of switch
16
B is coupled to filter
34
B of receive circuit
14
B. Switches
16
A and B perform the basic function of routing the transmit and receive signals associated with paths
40
A and B, respectively, to appropriate circuits
12
A-B and
14
A-B while providing adequate isolation. Switches
16
A and B are preferably devices which do not have appreciable loss characteristics.
When in a transmit mode, switches
16
A and B couple transmit input
42
to interface
44
. When in a receive mode, switches
16
A and B couple interface
44
to receive output
46
. Switches
16
A and B can be controlled by a control circuit or other device which places system
10
in a transmit or receive mode.
Transmit circuits
12
A-B and receive circuits
14
A-B preferably represent transmit and receive radio units for GSM and DCS bands in system
10
. The various components associated with other portions of system
10
are beyond the scope of the general high level architecture associated with switches
16
A and B and discussed in the present application.
System
10
is preferably implemented on a printed circuit board. The printed circuit board must be of minimal size in order to accommodate the decreasing size allowances for dual mode phones. Switches
16
A and B consume a large portion (e.g., almost a majority) of the circuit board real estate associated with the circuit components shown in FIG.
1
. Additionally, switches
16
A and B and are expensive. Therefore, conventional switches
16
A and B add significantly to the associated monetary and circuit board real estate costs of a dual mode phone design.
Thus, there is a need for a dual band phone architecture which only requires a single transmit-receive switch. Further, there is a need for a GSM/DCS dual mode phone architecture with reduced circuit board space requirements.
SUMMARY OF THE INVENTION
The present invention relates to a dual band phone including an antenna, a transmission path, a receive path, and a single transmit-receive switch. The transmission path includes a first transmit power amplifier and a second transmit power amplifier. The first transmit power amplifier provides transmit signals in a first frequency range, and the second transmit power amplifier provides the transmit signals in a second frequency range. The receive path includes a first filter path for receiving receive signals in a third frequency range and a second filter path for receiving receive signals in a fourth frequency range. The single transmit-receive switch has an antenna interface, a transmit input, and a receive output. The antenna interface is coupled to the antenna, the transmit input is coupled to the transmit path, and the receive output is coupled to the receive path.
The present invention further relates to a dual band phone architecture including a GSM radio transmission unit having a GSM output, a DCS radio transmission unit having a DCS output, at least one receive unit, a diplexer, and a single transmit-receive switch. The diplexer has a first input coupled to the GSM output, a second input coupled to the DCS output, and a diplexer output. The single transmit-receive switch has an antenna interface, a transmit input, and a receive output. The transmit input is coupled to the diplexer output, and the receive output is coupled to the receive unit.
The present invention still further relates to a dual band phone system including an antenna, a transmission path means, a receive path means, and a single transmit-receive switch means. The transmission path means provides transmit signals in a first frequency range and in a second frequency range. The receive path means receives receive signals in a third frequency range and in a fourth frequency range. The single transmit-receive switch means connects the transmission means to an antenna or the receive path means to the antenna.
According to one exemplary aspect of the present invention, a phone architecture utilizes only a single transmit-receive switch. A GSM-DCS diplexer is used to separate GSM and DCS signal paths before the transmit-receive switch. A low pass filter can be used to suppress harmonics in the individual GSM and DCS paths. The transmit-receive switch is preferably broad band enough to cover both GSM and DCS frequency bands and is disposed just before the antenna.
In accordance with another exemplary aspect of the present invention, the GSM and DCS power amplifiers can be switched off, depending upon the mode of operation (GSM mode or DCS mode). The transmit-receive switch preferably operates across the frequency range of 890 to 1880 MHz at a power of 35 dbm at GSM frequency bands and 32 dbm at DCS frequency bands. The transmit-receive switch is a GaAs device having low insertion losses between 0.5 dB to 1 dB in both DCS and GSM bands. In addition to simplifying conductor routing for the dual mode phone, the use of a sin
Conexant Systems Inc.
Kincaid Lester G.
LandOfFree
Dual mode phone architecture utilizing a single... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Dual mode phone architecture utilizing a single..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dual mode phone architecture utilizing a single... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3024633