Requirement:
The input (parasitic) capacitance due to the PASA will be .2pf to .3pf, which is similar to that expected external to the PASA (Hybrid and SDD anode node). The bipolar process can minimize noise effectively for such capacitance levels.
Justification:
The device has to meet the input and output capacitance of the connecting external components (SDD in, SCA out) without degrading S/N performance.