Amplifiers – With amplifier bypass means
Reexamination Certificate
2001-09-21
2004-03-23
Choe, Henry (Department: 2817)
Amplifiers
With amplifier bypass means
C330S149000
Reexamination Certificate
active
06710652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a feedforward amplifier and a communication equipment, which are primarily used for a base station device of mobile communication equipment.
2. Related Art of the Invention
In recent years, a high-output linear power-amplifier, compensated for distortion by a feedforward method, has been used for a base station device of mobile communication equipment.
FIG. 12
shows an example of the configuration of a conventional feedforward amplifier. In
FIG. 12
, reference numeral
1
denotes an input terminal,
2
an output terminal,
3
and
8
power splitters,
4
and
9
power-combiners,
5
and
13
vector adjustors,
6
a main amplifier,
7
and
10
delay circuits, and
14
an error amplifier, respectively. Further, symbols a to k and m added to the power splitters
3
and
8
and the power-combiners
4
and
9
show respective ports.
Hereinafter, the operation of the feedforward amplifier configured as described above will be described.
First, an input signal input from the input terminal
1
and including a plurality of carrier frequency components is split into two parts by the power splitter
3
, and the two parts are output from the port b and port c respectively. The signal output from the port b is amplified by the main amplifier
6
through the vector adjustor
5
, and then passes through the power splitter
8
and the delay circuit
10
, inputting into the port j of the power-combiner
4
. At this time, the signal including distortion components caused by intermodulation due to non-linearity of the main amplifier
6
in addition to the carrier frequency components are input into the port j.
Further, part of the output signal of the main amplifier
6
is took out from a port f of the power splitter
8
and input into a port h of the power-combiner
9
. On the other hand, the signal output from the port c inputs into a port g of the power-combiner
9
through the delay circuit
7
. Here, the vector adjustor
5
and delay circuit
7
are adjusted such that the carrier frequency components of the respective signals input into the port g and the port h may have the same amplitudes and opposite phases, thereby a signal having only the distortion components with the carrier frequency components canceled out being output from the port i.
Next, the signal output from the port i is amplified by the error amplifier
14
through the vector adjustor
13
and inputs into a port k of the power-combiner
4
. Here, the vector adjustor
13
and the delay circuit
10
are adjusted such that the distortion components of signals input into the port j and port k may have the same amplitudes and opposite phases, thereby a signal having only the carrier frequency components with the distortion components canceled out being output from a port m of the power-combiner
4
to the output terminal
2
.
FIGS.
13
(
a
) to (
d
) shows frequency spectra of signals at the ports a, d, i and m.
As shown in FIG.
13
(
a
), the frequency spectrum of the signal at the port a is composed of carrier frequency components. Also, as shown in FIG.
13
(
b
), the frequency spectrum of the signal at the port d is composed of carrier frequency components and distortion components. Further, as shown in FIG.
13
(
c
), the frequency spectrum of the signal at the port i is composed of only the distortion components with the carrier frequency components canceled out. Further, as shown in FIG.
13
(
d
), the frequency spectrum of the signal from the port m is composed of only the carrier frequency components with the distortion components canceled out.
However, the configuration of
FIG. 12
has a problem that a decrease in output power leads to a decrease in efficiency as shown in FIG.
14
. Here, the efficiency means the ratio of output power to consumption power.
Further, in a base station device and the like of mobile communication equipment that uses the configuration of
FIG. 12
, there is a problem that when the main amplifier fails, the device can not work and thus the communication stops completely.
SUMMARY OF THE INVENTION
Considering the above problems, the invention has an object to provide a feedforward amplifier and a communication equipment of which efficiency does not decrease even in the event of the reduction of output power.
Further, the invention has another object to provide a feedforward amplifier and a communication equipment of which communication does not stop completely even in the event of the failure of the main amplifier.
One aspect of the present invention is a feedforward amplifier comprising:
a first power splitter for splitting an input signal into two parts;
a first vector adjustor for adjusting the amplitude and phase of one output signal of said first power splitter;
a main amplifier for amplifying an output signal of said first vector adjustor;
a second power splitter for splitting an output signal of said main amplifier into two parts;
a first delay circuit for delaying the other output signal of said first power splitter;
a distortion detection power-combiner for synthesizing one output signal of said second power splitter and an output signal of said first delay circuit;
a second delay circuit for delaying the other output signal of said second power splitter;
a second vector adjustor for adjusting the amplitude and phase of the output signal of said distortion detection power-combiner;
an error amplifier for amplifying the output signal of said second vector adjustor;
a distortion suppression power-combiner for synthesizing the output signal of said second delay circuit and the output signal of said error amplifier; and
control means of at least stopping the operation of said error amplifier or said main amplifier depending on a predetermined condition.
Another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of said input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal level of a transmitting signal in a transmitting circuit,
wherein said predetermined condition represents said first signal level, and
when said detected first signal level is not higher than a predetermined value, said control means stops the operation of said error amplifier.
Still another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of a received signal in a receiving circuit,
wherein said predetermined condition represents said first signal level, and
when said detected first signal level is not lower than a predetermined value, said control means stops the operation of said error amplifier.
Yet still another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of said input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal level of a transmitting signal in a transmitting circuit, or the signal level of a received signal in a receiving circuit; and
second signal level detection means of detecting a second signal level that is the signal level of said output signal,
wherein said predetermined condition represents gain of said second signal level to said first signal level, and
when said gain is out of a predetermined value, said control means stops the operation of said main amplifier.
Still yet another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of an input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal level of a transmitting signal in a transmitting circuit,
wherein said predetermined condition represents said first signal level, and
when said first signal level is n
Fujiwara Seiji
Ishida Kaoru
Matsuyoshi Toshimitsu
Miyaji Masayuki
Choe Henry
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
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