Amplifiers – With semiconductor amplifying device – Including frequency-responsive means in the signal...
Reexamination Certificate
2002-03-28
2003-06-03
Mottola, Steven J. (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including frequency-responsive means in the signal...
C330S292000
Reexamination Certificate
active
06573797
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a high-frequency power amplifier, and relates, more particularly, to a class C power amplifier that uses a transistor as an amplifying element.
BACKGROUND ART
Among various kinds of digital modulations that are used for mobile communications or the like, there is a constant amplitude modulation system. In this constant amplitude modulation system, it is possible to use a class C power amplification. As is known well, class C power amplification is a system that has highest power amplification efficiency.
In other words, in general, while class A power amplification efficiency and class B power amplification efficiency are 50% and 70% respectively, class C power amplification efficiency is almost 100%.
However, the above 100% is an ideal value, and an actual value is far from this value. Further, in a high-frequency band of a several 100 MHz or above, to which the present invention refers, this value is much lower, and is about 50%, in reality. Generally known catalogs of amplifiers also show such a low value.
The fact that this power amplification efficiency is as low as about 50% in the high-frequency class C power amplifier has been reported as attributable to internal constants of transistors that form main portions of this amplifier. However, there has been a problem that, because of such low efficiency, the power consumption and the thermal loss of the high-frequency class C power amplifier are large.
DISCLOSURE OF THE INVENTION
In the light of the above problems, a cause of the low power amplification efficiency will be analyzed in the present invention. Further, it is an object of the present invention to provide a high-frequency power amplifier that can increase a realistic value from the conventional value of about 50% to about 70%.
In order to achieve the above object of the present invention, a current absorbing unit which absorbs a higher-harmonic frequency current contained in a signal of a fundamental wave (a fundamental amplification frequency) at which an amplifying element operates, is connected to an input side of the amplifying element.
REFERENCES:
patent: 5159287 (1992-10-01), Furutani et al.
patent: 5969575 (1999-10-01), Helms
patent: 6211738 (2001-04-01), Hecht
patent: 6300827 (2001-10-01), King
patent: 8-321727 (1996-12-01), None
patent: 9-83275 (1997-03-01), None
Fujitsu Limited
Katten Muchin Zavis & Rosenman
Mottola Steven J.
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