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AD9910 frequency sweep initial phase

Question asked by adr.mzg on Dec 8, 2016
Latest reply on Dec 8, 2016 by adr.mzg

Hello, I'm using an AD9910 DDS to generate a triangular frequency sweep continuausly, using the no-dwell mode. In order to test the acquisition system, I'm reading the output with a high speed ADC with SYNC_CLK as input clock and DROVER as acquisition trigger. Reading the datashet I expect that when the ramp reaches the low or the high limit, the phase accumulator clears, so that each sweep should start with a constant phase. However, when inspecting DROVER and the output, the phase seems to be different everytime (see attached oscilloscope captures, where blue is DROVER and yellow the output). Am I missing something? Thanks in advance!