Amplifiers – With plural amplifier channels – Amplifying different frequencies in different channels
Reexamination Certificate
2000-01-24
2001-06-19
Mottola, Steven J. (Department: 2817)
Amplifiers
With plural amplifier channels
Amplifying different frequencies in different channels
C330S010000
Reexamination Certificate
active
06249183
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a high-efficiency amplifying device.
High-efficiency amplifying devices as such have been known for some time, particularly if they are embodied as so-called class F amplifiers, e.g. see also “Solid State Radio Engineering” by Kraus and Bastian, John Wiley and Sons, New York, Section 14-4 Class F Amplification. It is essential for amplifiers with class F operation that resonance devices for a basic frequency and at least one harmonic be connected on the output side. As a rule, only twice or three times the basic frequency is used as a harmonic (e.g., RF Design, May 1996, pp 79-84: “An Introduction to class F Power Amplifiers” by F. H. Raab).
High-efficiency amplifying devices are of particular interest for accumulatoroperated or battery-operated devices with high frequencies, such as mobile telephones, so as to allow for long operating times with the limited energy supply.
A high-efficiency amplifying device for the 8-GHz band is described in the IEEE MTT-S Digest 1996, pp 689-692. For this device, a trapeze-shaped half-wave signal is generated in a pre-amplification stage, located in front of the power amplifying unit, from a sine-shaped input signal as a drive signal for the power amplifying unit, meaning a field-effect transistor. The 3
rd
and the 5
th
harmonic, 3fo and 5fo, are used in addition to the basic frequency in order to generate the trapezoid shape. In the report “High Efficiency Harmonic Control Amplifier” by Ingruber, Pritzel and Magerl, delivered during the IEEE MTT-S Intern. Symposium on Microwaves 1996, an amplifying device is described in which signal shares are generated in a preselection stage during the 2
nd
harmonic in addition to the basic frequency from the input signal. These signal shares are used for the drive signal to achieve an approximately half-wave shape for the drive signal.
Arrangements with harmonics in the drive signal of the power amplifying unit have the advantage that a high degree of efficiency is achieved without over-modulating the power amplifier.
The disadvantage of devices with harmonics in the drive signal of the power amplifying unit is the appearance of intermodulation products in the output signal, resulting from generated harmonics. The intermodulation products in the basic frequency cannot be suppressed by the basic-frequency band-pass filter on the output side.
U.S. Pat. No.-A-3,755,754 discloses a high-efficiency amplifying device, in which a drive signal for an active power amplifying unit is derived in a preselection stage from an input signal, in such a way that the drive signal contains signal shares for the basic frequency of the input signal and the at least one harmonic of this basic frequency, wherein the amplification characteristic of the preselection stage has an inverse phasefrequency characteristic to the power amplifier for the basic frequency.
A high efficiency amplifying device is also known from EP-A 0 252 364 where the amplification characteristic of the preselection stage has a signal-expanding course for the signal share in the basic frequency.
It is the object of the present invention to provide a high-efficiency amplifying device, which supplies good signal amplification with low disturbance and high linearity while requiring little expenditure.
SUMMARY OF THE INVENTION
The above object generally is achieved according to the present invention by a high-efficiency amplifying device, in which a drive signal for an active power amplifying unit is derived in a preselection stage from an input signal, such that the drive signal comprises signal shares with the basic frequency of the input signal and at least one harmonic of this basic frequency, and wherein the amplification characteristic of the preselection stage has a signal-expanding course for the signal share of the basic frequency and/or has an inverse phase-frequency characteristic to the power amplifying device for the basic frequency, and the signal share of the at least one harmonic is frequency selectively coupled out of the preamplification element output signal and is combined once more with the signal share of the basic frequency with an expanding amplification characteristic. Advantageous embodiments and modifications of the invention are disclosed and claimed.
The amplifying device according to the invention permits the operation of the active power amplifying unit in a non-linear characteristic range that is advantageous for the total degree of effectiveness. It also keeps the signal distortions low by compensating for the most part the intermodulation products generated around the basic frequency through the opposing phase influence of the signal-expanding characteristic of the preselection stage and/or the inverse phase-frequency characteristic.
The signal-expanding characteristic preferably is realized through forming the difference between an intermediate signal, generated based on a signal-compressing characteristic, and a non-distorted input signal. The signal shares for the at least one harmonic are preferably derived from the signal mixture, which develops in the preselection stage as a result of the non-linear characteristic.
In special cases, the linearity of the power amplifier can be improved through injection of the 2
nd
and 3
rd
harmonic.
The invention is illustrated in further detail below with the aid of exemplary embodiments and by referring to the Figures.
REFERENCES:
patent: 3755754 (1973-08-01), Putz
patent: 4376916 (1983-03-01), Glaberson
patent: 4450417 (1984-05-01), Folkmann
patent: 5510752 (1996-04-01), Gagon
patent: 196 37 582 (1997-03-01), None
patent: 0 047 825 (1982-03-01), None
patent: 0 252 364 (1988-01-01), None
patent: 0 255 652 (1988-02-01), None
patent: 0 330 774 (1989-09-01), None
patent: 2 158 625 (1985-11-01), None
patent: 5110357 (1993-04-01), None
patent: 063338728A (1994-12-01), None
Bosch Wolfgang
Petz Felix Anton
Daimler-Chrysler AG
Kunitz Norman N.
Mottola Steven J.
Venable
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