Figure 7-1 shows how the TMUX7219 has a transmission gate topology. Any mismatch in the stray capacitance associated with the NMOS and PMOS causes an output level change whenever the switch is opened or closed.

Figure 7-1 Transmission Gate Topology

The TMUX7219 contains specialized architecture to reduce charge injection on the source (Sx). To further reduce charge injection in a sensitive application, a compensation capacitor (Cp) can be added on the drain (D). This will ensure that excess charge from the switch transition will be pushed into the compensation capacitor on the drain (D) instead of the source (Sx). As a general rule, Cp should be 20× larger than the equivalent load capacitance on the source (Sx). Figure 7-2 shows charge injection variation with source voltage with different compensation capacitors on the drain side.

Figure 7-2 Charge Injection Compensation