Patent ID: 8457192

Claim:
A switch-modulator for a switched-mode radio-frequency power amplifier, the switch-modulator arranged to map a phase and amplitude of an input complex baseband signal, represented by an I-signal and a Q-signal, onto modulated output pulse sequences, and sample and modulate the I-signal and the Q-signal separately, a modulation comprising a time-shift of pulse positions within a sampling interval, the switch-modulator comprising: a first input to a separate I-signal path in the switch-modulator; a second input to a separate Q-signal path in the switch-modulator; and a third input to a quadrature clock generator in the switch-modulator, the quadrature clock generator being arranged to generate an I-clock signal and a Q-clock signal having a quadrature-shifted phase-relationship in order to delay the modulated I-signal pulse sequence relative to the modulated Q-signal pulse sequence, and to generate a time-shift of the pulse positions in the modulated output pulse sequences.