IC-friendly line codes for direct-conversion receivers

It is obvious that the offsets that arise in direct-conversion receivers can be canceled by employing DC notch filters after down conversion. However, the overall system performance (BER) will be severely degraded in narrowband systems if the modulation scheme peaks at DC-as is true for most currently-used spectrally-efficient applications. Thus, utilizing modulation formats with a null at DC make notch filtering feasible, but at the expenses of reduced spectral efficiency and detector complexity. We study a series of modulation methods and corresponding detectors. Our goal is to find an optimized system level solution to make direct-conversion receivers a practical solution.