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Delay because of MUX

Question asked by Suneel on Apr 5, 2011
Latest reply on Apr 18, 2011 by DeepV

HI All,

 

I want to measure delay between input and output in sample by sample processing in DSP system. The system is something like this.

 

ADC --> MUX  --> DSP21479 --> DAC

 

 

The Use of MUX in the system is to select one among the different inputs.The MUX  i am using is ADG1404. The truth table of the MUX is

 

 

EN A1 A0  S1 S2 S3 S4
0    X   X   Off Off Off Off
1    0   0   On Off Off Off
1    0   1   Off On Off Off
1    1   0   Off Off On Off
1    1   1   Off Off Off On
I have enabled MUX in my system and made it as static. i.e always state S1will be  selected(A1 =0 A2 =0).
I am running sample by sample system and ADC, DAC are running at 800KHZ. With this rate i am expecting as maximum of two samples delay(i.e 2.5usec) from input to output. But when i measure the delay i am getting around 7.5 usecs.( i.e 6 samples).
I am not sure  from where these extra four samples of delay is coming from.
WIll there be any delay because of MUX.
Thanks,
Suneel.

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