Switched-mode amplifiers and devices having such amplifiers include quadrature pulse-width modulation that is based on cartesian (as opposed to polar) coordinates. Two sets of pulses that represent respective in-phase and quadrature components of a conventional cartesian-coordinates input signal can be combined such that the combined set of pulses can be provided to a switched-mode amplifier without nonlinear cartesian-to-polar transformation and its associated wider internal bandwidth and other problems.