Patent ID: RE42532

Claim:
A power supply, comprising: a DC to DC buck pulse width modulator converter circuit having an input, a high side output and a low side output; a high side switch electrically connected intermediate a common output node and a voltage supply, said high side switch configured for controlling a flow of current therethrough dependent at least in part upon said high side output; a low side switch electrically connected intermediate said common output node and ground, said low side switch configured for controlling a flow of current therethrough dependent at least in part upon said low side output; a virtual ground amplifier having a first input, a second input and an output, said second input electrically connected to ground potential; a current feedback resistor electrically connected intermediate said common output node and said first input of said virtual ground amplifier; a variable impedance component electrically connected to said output of said virtual ground amplifier and to said first input of said virtual ground amplifier, said variable impedance component configured to vary in impedance dependent at least in part upon said output of said virtual ground amplifier; and a sample and hold circuit electrically connected intermediate said DC to DC buck pulse width modulator converter circuit and said variable impedance component, said sample and hold circuit configured to source a virtual ground current through said variable impedance component and to sample and hold said virtual ground current.