Patent ID: 6430402
Filing Date: 2002-08-06
Classification: H03F,H03G

Abstract:
An apparatus for transmitting signals over a communications channel, the apparatus comprising:an input signal source; a power amplifier having a data signal input coupled to the input signal source, a control signal input for receiving a control signal for controlling the power output of the power amplifier, and a power input for receiving a current from a power supply; an output power detector, coupled to the output of the amplifier, for generating a power measurement signal representing the power output of the amplifier; a current detector arranged to detect the current received by the power amplifier from the power supply and providing a current measurement signal representative of the current received from the power supply; a digital signal processor coupled to receive the current measurement signal and provide a reference signal dependant on the current measurement signal; a comparator, coupled to receive the reference signal and the power measurement signal, for generating an amplifier control signal; means for coupling the power amplifier output to the communications channel; a controller for increasing a power output of the amplifier in order to determine a current threshold value that limits the reference signal provided by the digital signal processor; and a storage device for storing the current threshold value.