8.3.2 Ultralow Charge Injection

The MUX50x have a simple transmission gate topology, as shown in Figure 38. 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 38. Transmission Gate Topology

The MUX50x have special charge-injection cancellation circuitry that reduces the source-to-drain charge injection to as low as 0.31 pC at V_S = 0 V, and ±0.9 pC in the full signal range, as shown in Figure 39.

Figure 39. Source-to-Drain Charge Injection

The drain-to-source charge injection becomes important when the device is used as a demultiplexer (demux), where D becomes the input and Sx becomes the output. Figure 40 shows the drain-to-source charge injection across the full signal range.

Figure 40. Drain-to-Source Charge Injection