Patent ID: 7646258

Claim:
An integrated circuit for digitally synthesizing a signal for FM transmission with a complex variable frequency digital IF signal, the integrated circuit comprising: a baseband audio processing block that is arranged to generate a first digital signal and a second digital signal in response to a left signal and a right signal, wherein the first digital signal is associated with a sum of the left signal and the right signal, and wherein the second digital signal is associated with a difference between the left signal and the right signal; a composite baseband generator block that is arranged to generate a signed digital composite baseband signal in response to the first digital signal, the second digital signal, and a pilot level; an up-sampler that is arranged to generate a digital sign extended frequency in response to the signed digital composite baseband signal such that the digital sign extended frequency has reduced alias components relative to the FM transmission; a station map that is arranged to generate a digital channel offset in response to a digitally represented base frequency number and a digitally represented station frequency number; a summer that is arranged to generate a digital level-translated composite signal as a sum of the digital channel offset and the digital signed digital composite baseband signal; a numerically controlled oscillator that is arranged to generate a phase signal in response to the digital level-translated composite signal; and a complex rotator that is arranged to generate the complex variable frequency digital IF signal in response to the phase signal and a transmit level that is specified by an in-phase input.