Amplifiers – With amplifier bypass means
Patent
1995-03-28
1997-07-01
Mullins, James B.
Amplifiers
With amplifier bypass means
330 52, H03F 132
Patent
active
056442688
ABSTRACT:
To reduce the size and power dissipation of a feed-forward amplifier, two identical high power amplifiers in a quadrature combined configuration function both as the main amplifier and as the error amplifier. The feed-forward amplifier has two control loops to increase amplifier linearity and reduce intermodulation distortion. A first loop is provided to subtract a properly scaled and delayed sample of the amplifier input spectrum from a scaled and phase shifted sample of its output spectrum which contains intermodulation distortion. The result of this subtraction (if the samples are maintained at the same amplitude and 180 degrees out of phase) is a signal rich in the intermodulation products of the amplifier. A differential phase-amplitude comparator which compares the signals prior to and after amplification and generates control signals for amplitude and phase trimmers for the signal prior to the amplifier and thus maintains the required equal amplitude and 180 degree phase relationship required for carrier cancellation. A second loop is provided to reduce distortion of the error signal due to effects of the amplifier.
REFERENCES:
patent: 4629996 (1986-12-01), Watanabe et al.
patent: 5130663 (1992-07-01), Tattersall, Jr.
patent: 5157345 (1992-10-01), Kenington et al.
patent: 5334946 (1994-08-01), Kenington et al.
Kenington, et al., RF Linear Amplifier Design, Centre for Communications Research, University of Bristol, United Kingdom, undated (after Jun. 1993 reference), pp. 1-10.
Brochure of Centre for Communications Research, Narrowband Amplifier Design, University of Bristol, United Kingdom, undated.
Brochure of British Technology Group Ltd., Broadband Linear Power Amplifier, London, United Kingdom, undated, 2 pages.
Mullins James B.
Spectrian, Inc.
Woodward Henry K.
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