A method and apparatus for generating an amplitude-modulated signal based on a modulation signal including first and second digital oscillators which are controlled based on first and second phase shifts derived from the modulation signal, and output first and second phase-modulated signals having a...http://www.google.de/patents/US5659272?utm_source=gb-gplus-sharePatent US5659272 - Amplitude modulation method and apparatus using two phase-modulated signals
