A power control method for a voltage controlled power amplifier and circuitry used in the method

Abstract

Abstract In a digital radio telephone transmitter an output pulse with e.g. cos²-shaped edges is produced by a voltage controlled power amplifier (1). When known control loop circuitry is used, the power (Pout) of the output pulse will rise almost step-wise at the beginning of the pulse, which leads to the spreading of the spectrum and to rise time delays of the output pulse with respect to the control pulse (TXC) at different power levels. According to the invention a good cos²-shape of the output pulse (Pout) and its tracking of the control pulse (TXC) almost without delay is achieved so that a squarewave pulse (Vp) is added to the control voltage (V2) of the power amplifier (1), the pulse (Vp) starting and ending substantially at the same time as the control pulse (TXC). In a preferred embodiment the squarewave pulse (Vp) is added to the control voltage (V2) only during that time when the control voltage (V2) is below that value, at which the the control loop begins to operate.

Inventors

• 👤 Risto Väisänen

Bibliographic Details