Self-grounded circuitry comprising: (a) a first signal channel conducting a first output signal on a first output conductor; (b) a charge pump powered by a first reference voltage and producing a control voltage signal on a control conductor, the control voltage signal having a first value if the first reference voltage is at a first level and having a second value if the first reference voltage is at a second level, wherein the first level is lower than the second level and the first value is lower than the second value; (c) a ground switch circuit including a first depletion mode transistor having a source coupled to the first output conductor, a gate coupled to receive the control voltage signal, and a drain coupled to a second reference voltage, the first depletion mode transistor having a first well region, a first parasitic diode including a PN junction between the source and the first well region, a second parasitic diode including a PN junction between the drain and the first well region, and a third parasitic diode including a PN junction between the first well region and a substrate ajoining the first well region; and (d) a first negative voltage protection circuit including 1) a first depletion mode protection transistor having a drain coupled to the first well region, a source coupled to a source of a second depletion mode protection transistor having a drain coupled to the first output conductor, the first and second depletion mode protection transistors each having a gate coupled to the control conductor, well regions of the first and second depletion mode protection transistors being connected to their sources, respectively, and 2) a level-shifting circuit coupled between the first well region and the control conductor. (a) a first signal channel conducting a first output signal on a first output conductor; (b) a charge pump powered by a first reference voltage and producing a control voltage signal on a control conductor, the control voltage signal having a first value if the first reference voltage is at a first level and having a second value if the first reference voltage is at a second level, wherein the first level is lower than the second level and the first value is lower than the second value; (c) a ground switch circuit including a first depletion mode transistor having a source coupled to the first output conductor, a gate coupled to receive the control voltage signal, and a drain coupled to a second reference voltage, the first depletion mode transistor having a first well region, a first parasitic diode including a PN junction between the source and the first well region, a second parasitic diode including a PN junction between the drain and the first well region, and a third parasitic diode including a PN junction between the first well region and a substrate ajoining the first well region; and (d) a first negative voltage protection circuit including 1) a first depletion mode protection transistor having a drain coupled to the first well region, a source coupled to a source of a second depletion mode protection transistor having a drain coupled to the first output conductor, the first and second depletion mode protection transistors each having a gate coupled to the control conductor, well regions of the first and second depletion mode protection transistors being connected to their sources, respectively, and 2) a level-shifting circuit coupled between the first well region and the control conductor. 1) a first depletion mode protection transistor having a drain coupled to the first well region, a source coupled to a source of a second depletion mode protection transistor having a drain coupled to the first output conductor, the first and second depletion mode protection transistors each having a gate coupled to the control conductor, well regions of the first and second depletion mode protection transistors being connected to their sources, respectively, and 2) a level-shifting circuit coupled between the first well region and the control conductor.