Amplifiers – With amplifier bypass means
Reexamination Certificate
2000-04-10
2001-12-25
Pascal, Robert (Department: 2817)
Amplifiers
With amplifier bypass means
C330S149000
Reexamination Certificate
active
06333676
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a control method used in a feedforward power amplifier, which receives a signal and on amplifying the signal causes non-linearities to the signal, the method comprising forming an adaptation factor by means of which the amplitudes and phases of signals propagating along different signal paths are adapted to one another.
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 different connections. In feedforward amplifiers distortion has been reduced by separating distortion from a signal after amplification. After separation, distortion has been added as negative distortion to a signal containing distortion, and thus the distortion components have canceled each other out. The resulting amplified signal has contained considerably less distortion than an unamplified signal.
Usually, the incoming end and outgoing end of the amplifier 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 provided with signal cancellation loops and error cancellation loops, where the phase and amplitude of the influencing signal have been adjusted. Adjustment has enabled reduction of distortion in the signal. The amplifier has been part of a control arrangement which has been able to adapt to the received signal to some degree.
Prior art amplifiers cannot, however, adapt to a signal if the power level of the incoming signal varies a lot, which is the case e.g. in CDMA radio systems. The temperature also causes problems to adaptation. The above-mentioned issues render signal adaptation more difficult since the non-linearities of an amplifier depend greatly on the fluctuation of the power level and on the temperature.
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, the adaptation factor also needs to change rapidly to correspond to the changed situation. In prior art solutions adaptation factors have, however, been constant, and thus the adaptation of the input signal has occurred too slowly. Slow adaptation has resulted in inaccurate adjustment.
BRIEF DESCRIPTION OF THE INVENTION
The object of the invention is to provide a control method and control arrangement which allow to solve the above-mentioned problems. This is achieved with a control arrangement described in the introduction, the control arrangement being characterized in that information is produced on the gain required by an amplifier, and on the basis of the information the adaptation factor to be used is changed in advance to correspond to the gain of the amplifier, which enables adaptation of the signal when the input power level changes rapidly.
The object is also achieved with a control arrangement, which comprises a feedforward power amplifier, which receives and amplifies a signal and which on amplifying the signal causes non-linearities to the signal, and adjusting members and adaptation means, which form an adaptation factor and control the operation of the adjusting members by means of the adaptation factor by adapting the amplitudes and phases of signals propagating along different signal paths to one another.
The control arrangement of the invention is characterized in that the control arrangement comprises control means, which produce information on the gain required by a power amplifier, and on the basis of the received information the control means order the adaptation means to adjust the adaptation factor in advance to correspond to the gain of the power amplifier, which enables adaptation of the signal also when the input power level changes rapidly.
The dependent claims relate to preferred embodiments of the invention.
The invention is based on the idea that information on the signal to be amplified is supplied to the control arrangement in advance, which enables adaptation of the control arrangement to the signal to be amplified in advance.
The control method and control arrangement of the invention have several advantages. The control arrangement comprises control means which receive information on power in advance. The control arrangement further comprises adaptation means, which form an adaptation factor on the basis of the power information. The control arrangement allows the signal to be amplified to be adapted to different signal paths when the input power level of a power amplifier changes rapidly. The control arrangement is suitable for power amplifiers of base stations in radio systems where the addition of e.g. one channel changes the average power required by a transmitter relatively much. The above-mentioned radio systems include CDMA and multi-carrier radio systems.
REFERENCES:
patent: 4580105 (1986-04-01), Myer
patent: 5157345 (1992-10-01), Kenington et al.
patent: 5334946 (1994-08-01), Kennington et al.
patent: 5742201 (1998-04-01), Eisenberg et al.
patent: 5963091 (1999-10-01), Chen et al.
patent: 2 107 540 A (1983-04-01), None
patent: 97/37427 A1 (1997-10-01), None
Nguyen Patricia
Nokia Networks Oy
Pascal Robert
Pillsbury & Winthrop LLP
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