Class D Amp power supply 'pumping'?

[jszair]

Is this pumping the result of large transient current flow through power supply resistance? Isn't that same for full or half bridge?

https://www.analog.com/library/analogDialogue/archives/40-06/class_d.html

The power supply voltage buses of half-bridge circuits can be “pumped” beyond their nominal values by large inductor currents from the LC filter. The dV/dt of the pumping transient can be limited by adding large decoupling capacitors between VDD and VSS. Full-bridge circuits do not suffer from bus pumping, because inductor current flowing into one of the half-bridges flows out of the other one, creating a local current loop that minimally disturbs the power supplies.

 

[crutschow]

The pumping is the result of the inductor inductance, not the resistance. The inductor stores energy when the current flows and tends to keep the current flowing after the bridge changes polarity, until the inductive energy is dissipated. It is this energy transferred back the power supply that is the source of the pumping. It's similar to the way a boost regulator can increase its output voltage above the input voltage.