Abstract: A power supply includes a first amplifier, a first current stage, and a second current stage. The first amplifier is configured to set an output voltage equal to a fixed input voltage for supplying to a device. The first current stage is configured to source and sink a first range of first output currents and provide a first measurement current representing a first output current. The second current stage is configured to source and sink a second range of second output currents and provide a second measurement current representing a second output current in response to the first range being exceeded. The first output current and the second output current are summed for supplying to the device. The first measurement current and the second measurement current are summed at a node.

Abstract: One aspect of the present disclosure is a control device responsive to control signals for electrically coupling an input node configured for connection to a low impedance source to an output node configured for connection to a transmission line. The control device includes a first controlled impedance device having a pair of controlled nodes connected between the input node and the output node. The first controlled impedance device has a control node for controlling impedance values between the controlled nodes. Also included is a closed loop control circuit connected to the control node of the first controlled impedance device for varying impedance between the controlled nodes continuously over a range of impedance values based on parameters sensed by a parameter sense device. The closed loop control circuit maintains a constant relationship between an output impedance of the control device and transmission line impedance.