An other highly sensitive point of this architecture is the
signal paths desynchronization effect. This effect is linked
to the fact that signals are differently processed. This delay
mismatch which degrades both ACPR (ACLR) and EVM
values, is mainly due to the passive filter (LC) inserted
between the output of the supply modulated system and the
supply pin of the RF PA. It is demonstrated in [12] that in
the case of a 16QAM 64 subcarriers OFDM modulation, the
disalignment as be to lower than Ts/30, Ts being the symbol
period, to limit ACPR. Thus, it is mandatory to compensate
for these delays using either a production tuning or adaptive
algorithms.