Abstract: An electronic switch (80) having a transistor (T) and a diode (D) formed on a substrate (82) is provided. The electronic switch (80) includes a common transistor collector and diode cathode region (81) of a first conductivity type formed in the substrate (82). The switch (80) also includes a transistor base region (83) of a second conductivity type formed in a first section of the collector region (81) and a transistor emitter region (84) of the first conductivity type formed in a section of the base region (83). Additionally, the electronic switch (80) includes a diode anode region (85) formed of the second conductivity type and in a second section of the collector region (81). At least a portion of the anode region (85) is selectively doped with a metallic dopant to provide centers for charge carrier recombination so as to decrease the recovery time of the diode (D).

Abstract: An overvoltage protection circuit for a pair of conductors carrying a balanced signal includes two similar protection elements connected in series between the conductors and two equal value resistors respectively connected in parallel with the elements, so that the junction point of the two elements is at a voltage midway between the voltages on the conductors and the protection elements present equal capacitances to the conductors. A third protection element is connected from the junction point of the two elements to ground to protect against excessive voltages relative to ground on the conductors. The voltage division provided by the resistors may be adjusted to improve the balance of the capacitances presented by the two protection elements.