Level shifter with shoot-through current isolation

Abstract

A level shifter circuit suitable for high voltage applications with shoot-through current isolation is presented. The level shifter receives a first enable signal and receives an input voltage at a first node and supplies an output voltage at a second node. The circuit provides the output voltage from the input voltage in response to the first enable signal being asserted and sets the output node to a low voltage value when the first enable signal is de-asserted. The level shifting circuit includes a depletion type NMOS transistor, having a gate connected to the output node, and a PMOS transistor, having a gate connected to the first enable signal. It also includes a first resistive element that is distinct from the NMOS and PMOS transistors. The NMOS transistor, the PMOS transistor and the first resistive elements are connected in series between the first and second nodes, with the NMOS transistor being connected to the first node. The level shifter further includes a discharge circuit connected to the second node and to receive a second enable signal. The second enable signal is asserted when the first enable signal is de-asserted and is asserted when the first enable signal is de-asserted, and the discharge circuit connects the second node to the low voltage value when the second enable signal is asserted and isolates the second node from ground when the second enable signal is de-asserted.