Amplifiers – With amplifier bypass means
Reexamination Certificate
2001-12-13
2003-06-03
Tokar, Michael (Department: 2817)
Amplifiers
With amplifier bypass means
C330S053000, C330S149000
Reexamination Certificate
active
06573792
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of electronic amplifiers. More particularly, in certain embodiments this invention relates to a feed forward linearization method and apparatus for amplifiers including but not limited to distributed RF amplifiers.
BACKGROUND OF THE INVENTION
Due to nonlinearities in the amplification process, amplifiers such as such as radio frequency (RF) power amplifiers can produce undesirable spectral components at the output. These undesired spectral components can create interference and may violate federal regulations. Feed forward compensation has been used in amplifiers to compensate for such linearities. A conventional arrangement of a feedforward amplifier is depicted in
FIG. 1
as amplifier
50
. The power amplifier
54
in this case amplifies the RF input signal applied to its input to produce an output signal which passes through delay
58
. The output of amplifier
54
is also passed through a pad
62
to reduce its magnitude. The input signal is also passed through a delay
66
and is subtracted from the output of the pad
62
to produce an error signal that represents the signal that should be removed from the output of amplifier
54
in order to linearize the amplifier
54
's amplification. This error signal is then amplified by error amplifier
72
and subtracted at element
76
from the output signal from delay element
58
. The error amplifier provides enough gain so that the amount of signal subtracted at
76
approximately matches the output level of the corresponding frequency content emerging from the delay
58
. In this manner, the RF output signal from the feedforward amplifier
50
is linearized and the spurious content of the RF output is reduced substantially.
REFERENCES:
patent: 3815040 (1974-06-01), Seidel
patent: 3886470 (1975-05-01), O'Neil et al.
patent: 4028634 (1977-06-01), Tentarelli
patent: 4583049 (1986-04-01), Powell
patent: 5166634 (1992-11-01), Narahashi et al.
patent: 5528196 (1996-06-01), Baskin et al.
patent: 5789927 (1998-08-01), Belcher
patent: 5977826 (1999-11-01), Behan et al.
patent: 6275105 (2001-08-01), Ghannouchi et al.
Olson Scott A.
Stengel Robert E.
Doutre Barbara R.
Fuller Andrew S.
Motorola INC
Nguyen Linh V
Tokar Michael
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