I have a pulse width modulator thats composed of a triangular wave generator and a comparator. This outputs a pulse width modulated signal, whose duty cycle I set by changing the comparator's V- voltage. I have measured the rise and fall times of my output waveform and they are 27uS (for both). I have been told by someone that such a slow waveform will cause power losses in the MOSFET I am using to drive a simple, small, DC Motor. I was told that this because with with a slow rise/fall time, the current and voltage waveforms overlap by a small bit and since P=VI, this causes power loss. Is this true? I'm skeptical because I don't understand why current and voltage are out of phase in the first - is this because the motor is an inductive load?