Controlled Complementer

This circuit shows how coincidence gates can be used as controlled complementers. These gates invert the input signal (IN) or keep it unaltered depending on the state of the control input (CTL). For the exclusive OR (XOR) gate: If CTL is low the output (XOROUT) follows the state of the input (IN), if CTL is high the output (XOROUT) is the complement of the input (IN). For the exclusive NOR (XNOR) gate: If CTL is low the output (XNOROUT) is the complement of the input (IN), if CTL is high the output (XNOROUT) follows the state of the input (IN).