LMX2820EVM: PFD Polarity can't be changed from negative mode to positve mode when the internal VCO is used

Hi, PLL team

we are using the LMX2820EVM board, the polarity of PFD can't be switched between positive and negative mode when the internal PFD and VCO are used. 

From the datasheet, there is a description about that the internal VCO operates under negative Vtune, thus for a passive loop filter the polarity setting as negative is ok. For some reason, I will use the inverted integrator active loop filter, thus the PFD polarity should be set as positive. 

When using the TICO Pro software to control the LMX2820 EVM board, the polarity of PFD can't be changed, when the internal VCO are used.

I wonder if the PFD polarity can't be changed when the internal VCO is used or just the TICO Pro software has limited this kind of usage.

I also wonder how to set the PFD polarity if the active loop filter is used. As the LMX2820 datasheet in 7.3.3 chapter just mentions that the polarity of the phase detector can be changed to suit for active loop filter, but I can't find more information about how to set.

Thanks

Chad