Abstract: An electronic signal processing apparatus has a signal switch with a first and a second transistor of normally-on type, having main current channels coupled between an internal node and a switch input and output, respectively. A diode provides a switchable signal coupling between the internal node and ground. A switch control circuit has a control output that is DC coupled to the main current channel of the first and the second transistor via the internal node to control conduction of the main current channels. The diode is also DC-coupled to the internal node so that a DC potential of a terminal of the diode that controls whether the diode is on or off is determined by a potential of the internal node. The diode is preferably incorporated in the DC current path from the control output to the internal node, so that the diode is forward-biased when a control voltage that makes the main current channels non-conductive is applied.