A digital amplifier and method are provided to convert digital base-band
signals to a pair of digital switching waveforms switching at a carrier
frequency to create a modulated RF signal. The digital amplifier contains
variable frequency suppressed carrier PWM generators that produce
in-phase and quadrature-phase differential signals, a mixer that combines
the differential signals, a decoder that decodes the combined signals,
and a power stage that receives signals from the decoder and provides an
amplified signal at the carrier frequency using switches. The mixer
combines the differential signals such that only one of the differential
signals is output in a period. The carrier generators have integral noise
shaping and use a random period signal to re-distribute quantization
noise to a band outside an RF band of interest and reduce EMI of the RF
signal.