A signal transmitter may include a waveform synthesis circuit and a signal transmission circuit. The waveform synthesis circuit may store values of a reference waveform for a selected channel of the signal transmitter, and use the stored values to generate values of reference waveforms for one or more other channels of the signal transmitter. The waveform synthesis circuit may further include a sampling boost circuit to generate one or more additional values for the reference waveforms. The waveform transmission circuit may generate signals for the channels of the signal transmitter based at least in part on the values of the reference waveforms, and transmit the signals via one or more antennas.