Current sense cascode amplifier

A current sense amplifier sensing current through a main switch of a converter. The amplifier includes first and second switch devices, an amplifier control circuit, a bias circuit, a current generator circuit, and a sense circuit. The main switch is coupled to an input, phase and control nodes. The first and second switch devices are smaller matching versions of the main switch and are both coupled to the main switch and form first and second nodes. The bias circuit is coupled between second and fourth nodes and the amplifier control circuit is coupled between first and third nodes. The current generator develops a first current through the amplifier control circuit and a second current through the bias circuit. The sense circuit has a current path coupled to the first node and is controlled by the third node to develop a sense voltage indicative of current through the main switch.