Control of attenuation and amplification in foward and feedback paths for power control for cartesian amplifiers
AssigneeLinear Modulation Technology Limited
InventorsWilliam J. Whitmarsh, Simon M. Whittle, Ian S. Parry
Life of this patent
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Abstract
A Cartesian amplifier is provided with a means of controlling its output power comprising a controllable attenuator in the amplifier forward path and a controllable amplifier in the feedback path. A control signal representing the required power level is applied to the attenuator and controllable amplifier and, in response thereto, the degrees of attenuation and amplification are varied in inverse proportion to one another.
Claims13
A power amplifier comprising an input terminal for receiving an input signal to be amplified, a forward amplification path connected to said input terminal and having a power amplifier output stage having an output, a feedback path from the output of said power amplifier output stage for feeding back a feedback signal proportional to the output signal of the output of the power amplifier output stage and having a variable gain amplifier for amplifying the feedback signal, difference means for driving the forward amplification path with a difference signal formed as the difference between the input signal to be amplified and the feedback signal and means connected to the forward and feedback paths for controlling the output power of the output stage, comprising control means for controlling, in a coordinated manner, the degree of attenuation of the signals in the forward path and the degree of amplification of the signals in the feedback path, in accordance with the signal representing a required output power level.
A radio transmitter comprising a converter having an output, for frequency translating at least one signal at baseband frequencies to transmission frequencies and at least one power amplifier connected to the output of said converter for power amplifying a signal which has been frequency translated by said converter for radiation via an aerial, the at least one amplifier comprising an input terminal for receiving a signal from the converter to be amplified, a forward amplification path connected to the input terminal and having a power amplifier output stage having an output, a feedback path from the output of the power amplifier output stage and having a variable gain amplifier for amplifying the feedback signal and means connected to the forward and feedback paths for controlling the output power of the output stage, comprising control means for controlling, in a coordinated manner, the degree of attenuation of signals in the forward path and the degree of amplification in the feedback path, in accordance with a signal representing a required output power level.
A radio communication system comprising a number of transceivers, at least one of the transceivers having at least one transmitter and at least one receiver, the at least one transmitter comprising a converter having an output, for frequency translating at least one signal at baseband frequencies to transmission frequencies and at least one power amplifier connected to the output of said converter for power amplifying a signal which has been frequency translated by said converter for radiation via an aerial, the at least one amplifier comprising an input terminal for receiving an input signal, from the converter, to be amplified, a forward amplification path connected to the input terminal and having a power amplifier output stage having an output, a feedback path from the output of said power amplifier output stage for feeding back a feedback signal proportional to the output signal of the output of the power amplifier output stage and having a variable gain amplifier for amplifying the feedback signal, difference means for driving the forward amplification path with a difference signal formed as the difference between the input signal to be amplified and the feedback signal and means for controlling the output power of the output stage, comprising control means for controlling, in a coordinated manner, a degree of attenuation of the signals in the forward path and the degree of amplification of the signals in the feedback path, in accordance with a signal representing a required output power level.
Dependencies are inferred from the claim text.