Abstract: A driver circuit (for example, in a switching power supply or in a Class-D switching amplifier) drives a gate of a switch during a transition with a low output impedance during an initial period and then for the remainder of the transition drives the gate with a midrange output impedance. The switch in turn switches current flow through an inductor. The driver circuit includes a “Drive Node Voltage Dependent Impedance Circuit” (DNVDIC) that couples the gate to a supply voltage node. In one embodiment, there are two resistive current paths through the DNVDIC. A non-linear device in the first current path switches from having a small to a large impedance when a voltage drop across the device falls below a threshold voltage. The resulting increase in impedance of the first current path decreases voltage edge rates and reduces noise, whereas the low initial impedance reduces transition power losses.

Abstract: A driver circuit (for example, in a switching power supply or in a Class-D switching amplifier) drives a gate of a switch during a transition with a low output impedance during an initial period and then for the remainder of the transition drives the gate with a midrange output impedance. The switch in turn switches current flow through an inductor. The driver circuit includes a “Drive Node Voltage Dependent Impedance Circuit” (DNVDIC) that couples the gate to a supply voltage node. In one embodiment, there are two resistive current paths through the DNVDIC. A non-linear device in the first current path switches from having a small to a large impedance when a voltage drop across the device falls below a threshold voltage. The resulting increase in impedance of the first current path decreases voltage edge rates and reduces noise, whereas the low initial impedance reduces transition power losses.