Efficient G-band digital communications using continuous phase modulation

The use of continuous phase modulation (CPM) for digital communications at G-band (216 GHz) has been investigated and demonstrated. The unique combination of constant envelope and multi-level symbol-maps of CPM offer the advantages of simultaneous high power-efficiency and spectral-efficiency. A transmitter/receiver communication link consisting of an I/Q modulator followed by a multiplier is used to generate 16-level CPM waveforms at 216 GHz. Waveforms with minimal distortion at the full saturated power of the transmitter were demonstrated without output power backoff. The system architecture provides an efficient technique for generating high power digital waveform, thus extending the link distance. The technique is ideal for upper millimeter-wave and terahertz communications where output power is limited.