Active pull-up and level shifter circuit

An active pull-up circuit which is operated between an upper voltage and a lower voltage and which is configured to pull-up an intermediate node to the upper voltage in reaction to an input voltage of the pull-up circuit falling from the upper voltage to an intermediate voltage;

• wherein the intermediate voltage lies between the upper voltage and the lower voltage;
• wherein the pull-up circuit comprises,
• a first transistor having a source terminal coupled to the upper voltage, a drain terminal coupled to the intermediate node and a gate terminal coupled to the input voltage;
• a load resistance coupling the intermediate node to the lower voltage;
• a second transistor having a source terminal coupled to the upper voltage, a drain terminal coupled to the intermediate node and a gate terminal coupled to a control node;
• and
• control circuitry configured to pull the control node to a voltage level of the intermediate node, subject to the input voltage falling from the upper voltage to the intermediate voltage.