Q
I am using AD9957, the reference clock is 48MHz, the system clock is 960MHz,
output 60MHz signal(Single Tone Mode), and met a problem.
1. When he configured "Matched Latency Enable " Bit as 1, after power on, the
9957's output isn't stable. Sometimes there is only 60MHz signal(0dBm),
sometimes there are 60MHz,120MHz and 240MHz harmonic frequency, sometimes the
output is 240MHz(forth of 960MHz);
2. When he configured "Matched Latency Enable " Bit as 0, the output is always
correct.
Whether the "Matched Latency Enable " will influence the output? He also want
to more descriptions about "Matched Latency Enable "?
A
The AD9957 and AD9910 are the same die. Bond wires separate the products
functions.
The match latency feature works on the AD9910.
A little about Match latency…...If a user wants to change two or more
parameters (frequency,phase,amplitude) at the same time and also wants that
change coincident at the DDS output, you must set the match latency bit to
logic 1. Otherwise, changes in the parameters will not be coincident.
Apparently, the AD9957 does not support the match latency feature..
The match latency bit should always be set to logic 0.