CLAMPING CIRCUIT TO A REFERENCE VOLTAGE, IN PARTICULAR TO GROUND, SUITABLE TO BE USED IN A TRANSMISSION CHANNEL FOR ULTRASOUND APPLICATIONS

摘要

A clamping circuit (10) to a voltage reference (GND) is described, of the type comprising at least one clamping core (11) connected to an output terminal (HVout) and having a central node (XC) connected to the voltage reference (GND) and in turn including at least one first and one second clamp transistor (MC1; MC2), connected to the central node (XC) and having respective control terminals (XG1, XG2), the clamping core (11) being also connected at the input to a low voltage input driver block (13). Advantageously according to the invention, the clamping core (11) further comprises at least one first switching off transistor (MS1) connected to the output terminal (HVout) and to the first clamp transistor (MC1), as well as a second switching off transistor (MS2) connected to the output terminal (HVout) and to the second clamp transistor (MC2), these first and second clamp transistors (MC1, MC2) being high voltage MOS transistors of complementary type and these first and second switching off transistors (MS1, MS2) being high voltage MOS transistors of complementary type and connected to the first and second clamp transistors (MC1, MC2) by having the respective equivalent or body diodes in anti-series so as to close themselves when the clamping circuit (10) is active and to sustain positive and negative high voltages when the clamping circuit (10) is not active.