The present invention relates to a polar modulation apparatus and method, in which an in-phase and a quadrature-phase signal are processed in the analog domain to generate an analog signal corresponding to a derivative of a phase component of said polar- modulated signal. The analog signal is then input to a control input of a controlled oscillator (40). As an example, the processing may be basedon a differentiate - and - multiply algorithm in the analog domain. Thereby, phase and envelope signals are generated in the analog domain and bandwidth enlargement due to the processing of the polarsignals and corresponding aliasing can be prevented to obtain a highly accurate polar-modulated output signal.