Full-scale range enhancement in a dual-path pulse width modulation playback system

A method comprising, in a system comprising a digital pulse width modulator subsystem having a tunable digital gain, a first path coupled to an output of the digital pulse width modulator subsystem and configured to drive an open-loop driver stage, and a second path coupled to the output of the digital pulse width modulator subsystem and configured to drive a closed-loop driver stage having a tunable analog gain, wherein the open-loop driver stage and the closed-loop driver stage are powered from a low-dropout (LDO) regulator that generates a supply voltage shared by the open-loop driver stage and the closed-loop driver stage:

• selecting one of the first path and the second path for processing an input signal to generate an output signal based on one or more characteristics of the input signal;
• setting the tunable digital gain to a maximum tunable digital gain and the tunable analog gain to a minimum tunable analog gain to compensate for an LDO attenuation of the LDO regulator when a magnitude of the input signal is lesser than a first threshold magnitude;
• setting the tunable digital gain to a minimum tunable digital gain and the tunable analog gain to a maximum tunable analog gain to compensate for an LDO attenuation of the LDO regulator when a magnitude of the input signal is greater than a second threshold magnitude;
• and
• varying the tunable analog gain and the tunable digital gain to compensate for the LDO attenuation when the magnitude of the input signal is in a range greater than the first threshold magnitude and lesser than the second threshold magnitude by increasing the tunable analog gain and decreasing the tunable digital gain as the magnitude of the input signal increases within the range and decreasing the tunable analog gain and increasing the tunable digital gain as the magnitude of the input signal decreases within the range.