IWR1642: Decrease Chirp BW by decreasing "ADC Valid Start Time" parameter

Hi,

My current configurations for the IWR1443 and IWR1642 has the same value 

for the "ADC Valid Start Time" parameter which is 7 micro seconds.

Is it possible to decrease this value to zero or to a number close to zero in order

to decrease the Tx BW?

according to the following diagram it should decrease it:

Thanks,

Boaz