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Posts: 9
Registered: ‎02-07-2012

DC out from FMC150 using ML605 reference design



I have been using the reference design for ML605 board. I have a couple of questions:

1. I need to transmit a low bandwidth (zero-IF) signal with a DC offset as it is positive all through. But I noticed that DC offset is getting lost in FMC150 as it may have a DC blocking Capacitor at the output. Is there any way I can bypass this/any other filter to achieve this?
2. One more issue is that I need to calculate the Power ( I^2+Q^2, where I and Q correspond to real and imaginary parts of a complex WCDMA sample)  in dBW/dBmW which requires logarithm of the value.   I and Q are fixed point(sintegers at the output of 3 rd interpolating filter in the reference design) values & I have been trying to use the arc tangent hyperbolic function of CORDIC core to get an approximation to logarithm. Is this what is usually done ? Please let me know if there is a better approach. It's a very crucial aspect of our problem as I need to build up a LUT based on the values.
Thanks in advance,