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Abstract

The present invention relates to a device and a method in a transmitter stage in a radio transmitter for modulating and amplifying an information signal for further transmission through a radio channel. The transmitter stage in the radio transmitter comprises a converting device (5) PCH, an amplifier control device (8) PAC, a power detector (13) and a power amplifier (2). Examples of the problems solved by the present invention are difficulties in reducing the power consumption, non-linearities in the output signal when using non-linear amplifiers in radio transmitters, and achieving a high signal-to-noise ratio in the output signal without connecting filter arrangements after such an amplifier. The solution according to the inventive method and device utilizes an information signal which has in earlier steps been divided in its polar components: a phase reference component signal (E.sub.phr) and an amplitude component signal (A.sub.amp). The phase reference component phase modulates a low noise high power signal source which has a constant amplitude. The amplitude of the obtained signal is then formed in an amplifier, which is controllable with the amplitude component signal (A.sub.amp). Its current consumption is registered and compared to a control value for the current. The amplifier is controlled towards this control value.

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First Claim