Generation Method of a Driving Signal for a Dual-Mode Supply Modulator in a 3-level Envelope Delta-Sigma Modulator Transmitter

A generation method of a driving signal for a dual-mode supply modulator (DMSM) that supplies dual dc supply voltages to a power amplifier (PA) in a 3-level envelope delta-sigma modulator (EDSM) transmitter is proposed and confirmed by simulation and measurement. This method is feasible in terms that it generates a DMSM driving signal of trackable speed by the DMSM through a real-time operation in the digital domain. Also, this method is suitable in terms that an intended relation between the DMSM driving signal and the output of a 3-level EDSM can be obtained, provided the design parameter of a lowpass delta-sigma modulator (LPDSM), out of band gain, is kept low (similar to 1.5). And, it is also shown that this condition for the design parameter of a LPDSM is not a limitation because it does not degrade the performance of the 3-level EDSM.