The CD4066BMS consists of four independent bilateral switches. A single control signal is required per switch. Both the p and the n device in a given switch are biased on or off simultaneously by the control signal. As shown in Figure 1, the well of the n channel device on each switch is either tied to the input when the switch is on or to VSS when the switch is off. This configuration eliminates the variation of the switch transistor threshold voltage with input signal, and thus keeps the on-state resistance low over the full operating signal range.