Charge injection Q(inj) is the amount of charge coupled during switching from the digital input to the switch output. The amount of charge coupled to the switch output is a function of the gate-drain capacitance and is a level change caused by stray capacitance associated with the NMOS and PMOS transistors that make up the analog switch. Typically CMOS switches and multiplexers are designed using a PMOS and NMOS device in parallel. For both devices to have the same RON, the PMOS device can be up to three times the size of the NMOS device. Hence, the gate-drain capacitance associated with the PMOS device is about three times that of the NMOS device and therefore the associated stray capacitance is approximately three times that of the NMOS device for typical switches found in the marketplace.