Patent ID: 7787563

Claim:
A polar transmitter, comprising: a first input for receiving an amplitude information signal; a second input for receiving an angle information signal; a frequency synthesizer coupled to said second input and operative to generate an angle modulated carrier signal in accordance with said angle information signal; a sigma delta modulator having an associated noise transfer function, said sigma delta modulator coupled to said first input and operative to generate a dithered amplitude signal therefrom and to selectively attenuate said noise transfer function; an amplifier coupled to said frequency synthesizer and said sigma delta modulator, said amplifier operative to control the amplitude of said angle modulated carrier signal in accordance with said dithered amplitude signal; wherein quantization noise exhibited by said amplifier is significantly attenuated at one or more selected frequencies; and wherein said sigma delta modulator comprises: at least one sigma delta stage; a comb filter; and a combiner operative to combine the output of said at least one sigma delta stage and said comb filter.