TS12A12511: about propagation time of TS12A12511

Vera,

Passive CMOS FET switches like the TS12A12511 have single digit ns to ps propagation delay.   The majority of that delay is due to the length of that path which the signal has to travel from one pin to the other.  The longest path in a CMOS FET switch primarily the length of the metal leadframe (pin) and bondwire that attaches to the silicon die.  The actual silicon CMOS FET switch drain to source delay isn't significant compared to the delay due to the length of pins and bond wires of the IC.

What type of signal are you passing through the switch that you are concerned about the propagation delay? 

How did you come to select the TS12A12511 device when there are lower cost options that specify propagation delay tpd?  What do you think about using the SN74LVC1G3157?

Thank you,

Adam