AbstractThe performance of wide‐band non‐linearly amplified, i.e. power efficient, 2‐, 4‐, 8‐, 16‐ and 32‐level PAM digital cable systems is studied. The effect of amplitude and phase non‐linearities (AM to AM) and (AM to PM) on the error rate performance and on the received eye diagrams is analysed by computer simulations and experimentally. We demonstrate that significant performance improvement could be attained by means of predistortion linearization, prior to the transmit (high power) amplifier, and by simple modification of the threshold decoding levels