Amplifiers – With semiconductor amplifying device – Including particular power supply circuitry
Reexamination Certificate
2000-03-24
2002-09-17
Mottola, Steven J. (Department: 2817)
Amplifiers
With semiconductor amplifying device
Including particular power supply circuitry
C330S129000
Reexamination Certificate
active
06452457
ABSTRACT:
DESCRIPTION
The present invention relates to an electronic apparatus comprising:
a power amplifier for producing a transmit power, formed by:
a final stage having a supply input for receiving a supply power,
a measuring circuit for measuring an electrical magnitude applied to said supply input,
a variable power supply circuit controlled by said measuring circuit for controlling the said transmit power.
The invention also relates to an amplifier suitable for such an apparatus.
The invention finds applications notably in mobile radiotelephony devices for which reduced power consumptions are required to lengthen the discharge period of the accumulator that feeds these devices. The high-frequency transmission amplifier consumes much energy. It is thus interesting to use high-efficiency power amplifier classes. This is the case with class D and others.
U.S. Pat. No. 5,497,125 describes a power amplifier of this type whose output power is controlled on the basis of a measurement of the power consumption. However, in this known amplifier there is a risk that there is non-negligible power dissipation in the current measuring circuit. Furthermore, the change of output power is effected via a variable gain preamplifier that also consumes a little energy.
The present invention proposes an apparatus of the type defined in the opening paragraph which offers reduced power consumption of the control circuit and is largely immune to noise.
Therefore, such an apparatus is characterized in that the said variable power supply circuit comprises:
a switched-mode power supply circuit having a switched-mode control input for defining its output voltage.
The idea of the invention is to utilize a switched-mode power supply that has the best efficiency.
An important characteristic feature of the invention comprises that said variable power supply circuit further includes a series power supply circuit that has a series control input for defining its output voltage and to which is connected a slaved circuit, so that the voltage difference between the input and the output of the series power supply circuit is minimized. This characteristic feature makes that the series pass transistor which is included in series power supply circuits works to saturation and thus has little energy consumption. Furthermore, the advantage is obtained that the switching noises of the switched-mode power supply are filtered without too much energy consumption.
These and other aspects of the invention are apparent from and will be elucidated, by way of non-limitative example, with reference to the embodiment(s) described hereinafter.
REFERENCES:
patent: 5115203 (1992-05-01), Krett et al.
patent: 5497125 (1996-03-01), Royds
patent: 6081161 (2000-06-01), Dacus et al.
patent: 0558793 (1993-09-01), None
patent: 9-181536 (1997-07-01), None
Ham Radio Outlet Winter 1999 Catalog pp. 72-73, Oct. 15, 1999.
Koninklijke Philips Electronics , N.V.
Le Pennec Gwenaelle
Mottola Steven J.
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