AD8346: SSB phase noise

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Aug 10, 2016
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 I am concerned about the SSB Phase noise and how to improve the
performance. Would you please help to give some advice on this issue?


When we say phase noise at transmit signal, it might be mainly originated from
local, of course some portion would be from non-linearity(harmonics
distortions..) of the modulator. But it is mainly discussed at local. As you
can see below (figure 1), phase noise of local spreads the desired signal. So
if the customer wants to get the phase noise performance mentioned below at
Modulator output, a good local source is required. At modulator, Local
feedthrough and Sideband suppression (USB at below graph) are main parameters.
These LO leakage, sideband suppression and harmonics affect performance like
EVM, ACLR. Baseband offset compensation can be used to reduce LO leakage.
Amplitude and phase compensation can be used to improve sideband suppression.
For this correction, please refer to the application note AN-1039.

Figure 1

Figure 2