Amplifiers – With control of power supply or bias voltage – With control of input electrode or gain control electrode bias
Patent
1995-05-23
1997-01-28
Mullins, James B.
Amplifiers
With control of power supply or bias voltage
With control of input electrode or gain control electrode bias
330144, 330279, 330284, 455126, H03G 320
Patent
active
055981267
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method and an arrangement for controlling the operation of a high-frequency power amplifier.
In GSM transmitters, for instance, specifications place rigid restrictions also on the operation of the transmitter as well as on switching on and off the transmission power. At power control and especially at switching off and reswitching the power, strict limit values shall be observed, particularly as far as the range of variations in power levels is concerned. When transmission power is switched off at a GSM transmission according to the specifications, it should be possible to reduce the transmission power during idle time slots between frames by at least 70 dB, in practice however by 80 dB, which can be carried out by decreased gain and by using RF range switching means providing an attenuation of about 40 dB, in addition to the 40 dB obtained by the control of the amplifier. One problem with the previous solutions is that the dynamic range of detector means is only about 40 dB.
In some methods and arrangements according to the prior art, the transmission power is switched off by using a switching means positioned in a power switching loop on the input side of an amplifier, in which case the signal path breaks, however, and the detector output remains floating in a way. This generates a control signal undefined in its details in a control means of the input side of the amplifier, which in turn causes problems, i.e. practically a control error in a situation when the transmission power shall be switched on again. A control error may also cause a decrease in attenuation when the power is switched off. This restricts the permitted maximum gain between the detector and the control means as well, which maximum gain determines in turn the accuracy of the output power in an ON state. Some known solutions are disclosed in European Patent Applications 0 481 524, 0 546 693 and 0 397 444, U.S. Pat. No. 5,128,629 and WO 91/12661.
SUMMARY OF THE INVENTION
The method comprises inputting a signal to be amplified to a high-frequency power amplifier in a forward line, generating a sample signal from the forward line on the output side of the high-frequency power amplifier to a feedback line, detecting the sample signal by a detector means, controlling the high-frequency power amplifier via the feedback line by a control means connected to the input side of the high-frequency power amplifier from a gain state to an OFF state by switching off the signal of the forward line and bringing the high-frequency power amplifier from the OFF state back to the gain state by switching on the signal of the forward line.
The arrangement according to the invention comprises a high-frequency power amplifier connected to a forward line and having an input side and an output side, a feedback line between the input side and the output side of the high-frequency power amplifier, a control means connected to the input side of the high-frequency power amplifier and communicating with the feedback line, a sampling means and a detector means connected to the feedback line between the output side and the input side of the high-frequency power amplifier as well as a switching means connected to the forward line for bringing the high-frequency power amplifier to an OFF state controlled by a control signal.
The present solution relates especially to multichannel radio transmitters and how to switch on the transmission power of a high-frequency power amplifier of a radio transmitter and particularly how to switch off the transmission power, i.e., how to bring it to an OFF state. One example of radio transmitters is a base station radio transmitter of a GSM mobile telephone network utilizing a TDMA system, the high-frequency power amplifier of which radio transmitter amplifies the signals to be received from a modulator before these are inputted to an antenna.
The object of this invention is to set forth a novel method and arrangement for controlling the operation of a high-frequency power amplifie
REFERENCES:
patent: 5054116 (1991-10-01), Davidson
patent: 5128629 (1992-07-01), Trinh
Mullins James B.
Nokia Telecommunications Oy
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