The switching function inside this device is done by means of a pair of P and N-channel MOSFETs connected in-parallel. This combination allows analog signals to flow in either direction through the switch, just like its mechanical equivalent. When the control input is off, the gate N-channel FET is off. Since the P-channel gets its control signal from an inverter, it is also off. Therefore, no signal can pass through the switch. When the control input is on, the gate of the N-channel FET is on and the P-channel FET is zero, so both paths are on and the signal can flow either way through the switch.