DAC38J84: about 'Small Fractional Delay' function

Min hu,

The small fractional delay is just a FIR filter with programmable coefficients. The coefficients are given in the datasheet. It is meant for delaying either I or Q with respect to the other (Q or I) to correct a fixed time delay mismatch. The other signal goes through a matched delay line to match the group delay of the FIR filter. The attached zip file contains the config files for the DAC GUI so you do not have to manually type them in.

This TI design (http://www.ti.com/lit/ug/tidu673/tidu673.pdf) contains a section on using the fractional delay for sideband suppression (section 3.6).

Regards,

Jim

Fractional Filters.zip