At&t Wireless Communications Products Limited

Christopher J Nunn

A method and apparatus for controlling an amplifier power output, in particular, a transmitter RF Amplifier includes a control circuit connected to the RF Amplifier. The control circuit derives a control signal from a shaper circuit and this control signal is applied, together with a feedback signal representative of the flow of dc current through one of the stages of the amplifier, to a comparator to generate an error signal. The error signal is applied to a common amplifier base bias line. Preferably, all of the stages of the error amplifier are in a saturated state so that the effect of the error signal on the bias line causes the amplification envelope of the transistors in the amplifier to follow the error signal, thus generating a pulsed output signal having an envelope shape corresponding to the control signal.

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Winchester, United Kingdom

Christopher J Nunn