Patent ID: 8143944
Filing Date: 2012-03-27
Classification: H03F

Abstract:
1. An apparatus comprising: a class-D amplifier having a low-side recycling mode, a pair of low-side NMOS transistors, and a pair of output terminals; a sample-and-hold (S/H) circuit that is coupled to the pair of output terminals, wherein the S/H circuit samples a voltage on each of the pair of output terminals of the class-D amplifier when its associated low-side NMOS transistor is actuated; a current generator that is coupled to the S/H circuit, wherein the current generator uses the voltages on the pair of output terminals sampled by the S/H circuit to minor the drain-source voltages of the pair of low-side NMOS transistors on a pair of sense transistors, and wherein the drain-source voltages mirrored on the pair of sense transistors generates a pair of sense currents; and a current-to-voltage (I-to-V) converter that is coupled to the current generator so as to convert the sense currents to a sense voltage.