Telecommunications – Transmitter – With coupled antenna
Reexamination Certificate
1999-12-13
2002-10-29
Nguyen, Lee (Department: 2683)
Telecommunications
Transmitter
With coupled antenna
C455S091000, C455S101000, C455S127500
Reexamination Certificate
active
06473600
ABSTRACT:
BACKGROUND
1. Technical Field
This disclosure relates to mobile communications and more particularly, to a mobile communication device with increased transmitter power efficiency.
2. Description of the Related Art
Portable communications systems typically rely on radio frequency transmissions that are sent and received using antennas. Conventional mobile phones employ a whip antenna for receiver functions and transmitter functions on a shared basis. The receive and transmit circuits are accommodated to provide both the receive and transmit functions through the same antenna.
Referring to
FIG. 1
, a schematic diagram of a portion of a mobile phone
10
is shown. Mobile phone
10
employs a receiver/transmitter (Rx/Tx) whip antenna
11
with a duplexer or switch
12
. Duplexer
12
permits access to both receiver circuitry
14
and transmitter circuitry
16
. Receiver circuitry
14
includes a low noise amplifier (LNA)
18
which receives a radio frequency signal. A band pass filter (BPF)
20
filters the signal. A mixer
22
mixes the filtered signal with a signal from a local oscillator
24
to output an intermediate frequency (IF) signal on a line
26
. The received signal is processed as is known in the art.
Transmitter (Tx) circuitry
16
includes an inphase/quadrature (I/Q) modulated signal
28
which is mixed by mixer
30
with a signal from local oscillator
24
. The mixed signal is amplified by a power amplifier driver
32
and then filtered by a band pass filter (BPF)
34
. The filtered signal is then amplified by a power amplifier
36
. After being amplified by amplifier
36
, the signal is transmitted from antenna
11
. Referring to
FIG. 2
, other prior art designs have employed separate (dedicated) patch antennas
40
and
42
for receiving and transmitting signals, respectively.
These typical antenna arrangements of mobile phones, include a Tx power amplifier
36
which is always ON (OFF in stand-by mode) and is working with a wide range of transmit power levels controlled by the infrastructure of mobile phone networks. Tx power amplifier
36
typically has maximum power efficiency at the maximum Tx power output levels. Correspondingly, operating at lower Tx power levels means low efficiency for the Tx power amplifier.
Proposed suggestions to address the efficiency problem have included implementing switches or linearization techniques. Linearization techniques include employing non-linear amplification which is more power efficient and then applying a linear scheme. Such techniques suffer from high implementation costs for transmission circuitry. Therefore, a need exists for a portable communication device which provides high power efficiency without high costs for transmission circuitry. Less power usage is desirable, which in mobile phone systems, increases talk time, for example.
SUMMARY OF THE INVENTION
A transmission portion of a front end for a portable communication device, in accordance with the present invention, includes a first transmission antenna coupled to a first output of a branching device for transmitting signals having a power below a threshold value. A power amplifier is coupled to a second output of the branching device. The power amplifier provides amplification to signals to be transmitted. A second transmission antenna is connected to an output of the power amplifier such that the power amplifier is switched off for transmission signals having a power below the threshold value and switched on to amplify transmission signals above the threshold value.
A front end for a portable communication device, in accordance with the present invention, includes a transmission portion having a first transmission antenna coupled to a first output of a branching device for transmitting signals having a power below a threshold value, and a power amplifier is coupled to a second output of the branching device. The power amplifier provides amplification to signals to be transmitted, and a second transmission antenna is connected to an output of the power amplifier such that the power amplifier is switched off for transmission signals having a power below the threshold value and switched on to amplify transmission signals above the threshold value. A receiver portion includes a receiver antenna coupled to a receive mixer for receiving signals for the front end. A local oscillator is included for providing signals to down convert the received signals and up convert the transmission signals for the front end.
In alternate embodiments, the first and second antennas may include patch antennas, embedded antennas or other types of antennas. The branching device may include a switch or a splitter. The communication device may include a mobile phone, a two-way pager, a personal digital assistant, or other transmitter device. The mobile phone may include a code division multiple access phone having a transmission power range of about 80 decibels. The power amplifier may provide a gain of 30 decibels and the threshold value is about 30 decibels below a largest transmission value of the transmission power range. The power amplifier may provide a gain G and the threshold value is less than a largest transmission value of the transmission power range minus G. A power sensor may be adapted for sensing a power level of received signals and outputs an enable signal to switch the power amplifier on when the sensed power is below a value, and disables the power amplifier when the sensed power is above the value. The transmission portion may further include a coupler adapted for sensing a power level at an output of the power amplifier for switching the power amplifier off when the sensed power is below a value and enabling the power amplifier when the sensed power is above the value.
These and other objects, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
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patent: 5613219 (1997-03-01), Vogel et al.
patent: 5758269 (1998-05-01), Wu
patent: 5909643 (1999-06-01), Aihara
patent: 6006117 (1999-12-01), Hageltorn et al.
patent: 6101374 (2000-08-01), Kono
patent: 6118989 (2000-09-01), Abe et al.
patent: 6240279 (2001-05-01), Nitta et al.
patent: 6343208 (2002-01-01), Ying
patent: 0752735 (1997-01-01), None
patent: WO9734377 (1997-09-01), None
Koninklijke Philips Electronics , N.V.
Nguyen Lee
Nguyen Simon
Slobod Jack D.
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