Input stage resistant against negative voltage swings

Abstract

Apparatus () comprising a level shifter () connectable to a signal input () for receiving an input signal (s(t)) with a negative signal swing. The level shifter () provides for a DC shift of the input signal (s(t)) to provide an output signal (r(t)) with positive signal swing. The level shifter () comprises an amplifier () with a first input (), a second input (), and an output (). A first capacitor (C), a second capacitor (C), a reference voltage supply (), and a transistor () serving as a switch, are arranged in a network as follows: the first capacitor (C) is arranged between the signal input () and the first input (), the second capacitor (C) is arranged in a feedback-loop () between the output () and the first input (), and the reference voltage supply () is connected to the second input (). The transistor () is arranged in a branch () that bridges the second capacitor (C), whereby a control signal (CNTRL) is applicable to a gate () of the transistor () in order to allow the level shifter () to be reset from time to time.