Amplifiers – With amplifier bypass means
Reexamination Certificate
2000-04-14
2001-05-08
Pascal, Robert (Department: 2817)
Amplifiers
With amplifier bypass means
C330S052000, C375S297000
Reexamination Certificate
active
06229391
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an adaptation method used in an amplifier arrangement, the method comprising amplifying a signal entering the arrangement in a feedforward manner, and using complex factors &agr; and &bgr;, which are adapted in order to adjust the phase and amplitude of an input signal to the amplifier arrangement.
BACKGROUND OF THE INVENTION
Broadband amplifiers and power amplifiers, in particular, cause distortion to a signal, since the amplifiers function non-linearly at least to some degree. Besides distortion amplifiers cause for example noise. The influence of distortion caused by amplifiers has been reduced by means of feedforward amplifiers.
Usually, the incoming end and outgoing end of feedforward amplifiers have to be adapted to signal paths. Processing of signals always causes some delay to a signal. For this reason adaptation of the delay and gain requires particular accuracy so that the amplifier would function as desired in all operational environments. Prior art amplifiers have been part of an amplifier arrangement which has been provided with signal cancellation loops and error cancellation loops. The amplifier arrangement has adjusted the phase and amplitude of a signal acting on the loops, which has enabled reduction of distortion in the signal. The amplifier arrangement has also been able to adapt to the received signal to some degree.
Special factors, which can be denoted with &agr; and &bgr;, are employed for adjusting the phase and amplitude. The factors are changed and adjusted by means of an adaptation factor, which is denoted with K. When the power level of an input signal changes rapidly, &agr; and &bgr; also need to change rapidly to correspond to the changed situation. In prior art solutions the same method has been used for adaptating both factors, which has caused problems. Problems have appeared particularly when a pilot signal has been used in adaptation.
A pilot signal, power minimization method and gradient method, for example, have been employed in adapting factors &agr; and &bgr;. However, the same method of adapting factors has been used in both cancellation loops, and thus any errors in the factors have been dependent on one another. The prior art methods have also suffered from other problems because the pilot signal has typically been used before signal amplification, in which case the pilot signal has caused noise and therefore it has been necessary to filter the signal out of the output of the amplifier.
BRIEF DESCRIPTION OF THE INVENTION
The object of the invention is to provide an adaptation method and amplifier arrangement which allow to solve the above-mentioned problems. This is achieved with the adaptation method described in the introduction, which is characterized in that complex factor a is adapted by attenuating an amplified signal, by supplying part of a signal entering the arrangement for adaptation, and by controlling adaptation of complex factor &agr; with part of the signal whose phase and amplitude are adapted, by subtracting the attenuated signal from the adapted signal; complex factor &bgr; is adapted by forming a predetermined signal, which is added to the amplified signal, by forming a conjugate signal of the adapted signal and by multiplying it by the predetermined signal, by adapting factor &bgr; by the signal obtained as a result of multiplication, factor p being used for adapting the phase and amplitude of the formed sum signal.
This object is also achieved with an amplifier arrangement, which comprises feedforward amplifying means which amplify a signal entering the arrangement, and adjusting means which use complex factors &agr; and &bgr;, which are adapted in order to adjust the phase and amplitude of an input signal to the amplifier arrangement.
The amplifier arrangement of the invention is characterized in that it comprises attenuation means which attenuate the signal amplified by amplifying means, means which subtract the attenuated signal from the adapted signal, adjusting means which receive part of the signal entering the arrangement for adaptation by factor &agr;, which is adapted partly by the signal obtained from the adapted signal, means which are connected to the outgoing end of the amplifier arrangement and form a predetermined signal, adders which add the predetermined signal to the signal amplified by the amplifier, means which form a conjugate signal of the adapted signal and multiply the conjugate signal by the predetermined signal and control adaptation of factor &bgr; with the signal obtained as a result of multiplication.
The dependent claims relate to preferred embodiments of the invention.
The invention is based on the idea that both factor &agr; and factor &bgr; are formed using different adaptation methods.
The adaptation method and amplifier arrangement of the invention provide several advantages. The amplifier arrangement uses a pilot signal for adapting the factors. The pilot signal is used after the input signal of the amplifier arrangement has been amplified. Thanks to the method the pilot signal can be eliminated, and thus the pilot signal does not need to be filtered at the outgoing end of the amplifier arrangement. Furthermore, the method allows to render the errors of the signal cancellation loop and error cancellation loop independent of one another, and consequently the requirements for accuracy of the amplifier arrangement can be reduced. The amplifier arrangement is suitable for use in power amplifiers of base stations in radio systems. These include CDMA and multi-carrier radio systems.
REFERENCES:
patent: 3922617 (1975-11-01), Denniston et al.
patent: 4580105 (1986-04-01), Myer
patent: 5157345 (1992-10-01), Kenington et al.
patent: 5455537 (1995-10-01), Larkin et al.
patent: 5815036 (1998-09-01), Yoshikawa et al.
patent: 6066984 (2000-05-01), Tomaru et al.
patent: 2107540 (1983-04-01), None
patent: 97/37427 (1997-10-01), None
International Search Report.
Altera Law Group LLC
Nguyen Patricia T.
Nokia Networks Oy
Pascal Robert
LandOfFree
Adaptation method and amplifier arrangement does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adaptation method and amplifier arrangement, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adaptation method and amplifier arrangement will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2519779