Amplifiers – Combined with automatic amplifier disabling switch means
Reexamination Certificate
1999-05-24
2001-03-13
Mottola, Steven J. (Department: 2817)
Amplifiers
Combined with automatic amplifier disabling switch means
C330S133000, C330S140000
Reexamination Certificate
active
06201440
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power amplifier, and in particular, to a power amplifier whose structure is reduced in size.
2. Description of Related Arts
Two kinds of output control systems have been employed for the conventional power amplifiers. In an output control system, as shown in
FIG. 1
, bias voltages of linear amplifiers
3
,
4
and
5
are kept constant to keep their gains constant, and programmably variable gain amplifier
2
is arranged before input terminal
6
of power amplifier
1
, and the magnitude of an input signal applied to power amplifier
1
is changed by variable gain amplifier
2
. In the other system, as shown in
FIG. 2
, the gain of power amplifier
1
is changed by controlling the bias voltage of linear amplifiers
3
,
4
, and
5
.
In the amplification mode of the conventional power amplifier described above, in particular, in an amplitude modulation mode and a phase modulation mode, since the data are transmitted by changing of amplitude component, a distortion produced during the compression of the data by the power amplifier, deteriorates the quality of the data. Therefore, the power amplifier needs to be used in a linear amplification range, which reduces the efficiency of the power amplifier. This is a serious matter to induces a problem that the power amplifier itself or the control system therefor needs to be selected according to the modulation mode of signal.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a power amplifier which does not require to be changed according to the kinds of signals to be amplified.
In order to achieve the object described above, a power amplifier in accordance with the present invention can execute power amplification at least for a mode of signal and comprises at least one amplification path for a mode of signal, means for selectively connecting the amplification path corresponding to an input signal and bias control means for controlling the bias voltage.
Further, it is preferable that the amplification path described above comprises a first amplification path including a first variable gain amplifier and at least one linear amplifier, and a second amplification path having a non-linear amplifier in addition to the first amplification path, that the means of controlling bias voltage described above comprises a wave detector for detecting an output power level and a comparator for outputting the difference between a level of input wave and the output level detected by the wave detector, and that the first variable gain amplifier and the linear amplifiers are employed commonly for the first and second amplification paths by switching to feed the corresponding required bias voltage.
Further, it is preferable that, in the first amplification path described above, the output of the first variable gain amplifier which is controlled to keep a required amplification factor by being controlled its bias voltage through the bias control means described above and the linear amplifiers are kept to maintain an amplification factor at a predetermined level with another bias control means, and that, in the second amplification path, the output of the first variable amplifier is kept to a constant amplification factor at the predetermined level, to apply to the group of amplifiers including the above-stated linear amplifiers and the above-stated non-linear amplifier, which amplify the power to a required output level by being controlled their bias voltages through the output of the bias control means.
Further, the present invention includes a power amplifier further comprising an exterior second variable gain amplifier to which a bias voltage is applied in parallel to the first variable gain amplifier described above and which is connected to the input side of the first variable amplifier described above.
Still further, the present invention includes a power amplifier in which, for an analog signal, a power amplification path after the first variable gain amplifier described above is set to a saturated state and the exterior second variable gain amplifier described above amplifies the analog signal to a high power level by adjusting the bias voltage thereof and outputs it to the power amplification path and the power amplification path amplifies the power of the analog signal, thereby reducing noises in a receiving band when the power of the signal is amplified, and that, for a digital signal, the power amplification path described above is set to a level below the saturated state by adjusting the bias voltage thereof and amplifies the output of the exterior second variable gain amplifier described above.
Furthermore, the present invention includes a power amplifier further comprising an inter-stage filter between the exterior second variable gain amplifier described above and the first variable gain amplifier described above to suppress a noise which is used to occur in the receiver side.
REFERENCES:
patent: 5530923 (1996-06-01), Heinonen et al.
patent: 5841319 (1998-11-01), Sato
patent: 5909643 (1999-06-01), Aihara
patent: 4-948808 (1992-02-01), None
patent: 6-53753 (1994-02-01), None
patent: 6-196955 (1994-04-01), None
patent: 9-148852 (1997-06-01), None
McGuireWoods LLP
Mottola Steven J.
NEC Corporation
LandOfFree
Power amplifier and control circuit thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power amplifier and control circuit thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power amplifier and control circuit thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2517537