Impact of Non-idealities on the Performance of Delta-Sigma/Manchester-modulated Microwave signals

The effects of non-idealities including clock jitter, rise/fall-time mismatch of a pulse, and pulse-amplitude-level non-linearity on conventional delta-sigma-only and Manchester/delta-sigma-modulated microwave signals are studied. According to the experimental and simulation results, the Manchester/delta-sigma scheme is more vulnerable to jitter than the conventional delta-sigma scheme due to the higher number of pulse transitions by Manchester codes. It is found that, however, because of the repetitive (or multi-pulse) nature, the Manchester/delta-sigma system shows better signal quality performance against a rise and fall time asymmetry. This is mainly because the Manchester pulse waveform is more similar to a return-to-zero format where every encoded bit has both rising and falling edges and is therefore immune to the waveform asymmetry.