Bias supply selection circuit, method of operation thereof and power supply employing the same

摘要

The present invention provides a bias supply selection circuit employable with a linear regulating device configured to provide a first bias supply voltage and a main bias supply stage configured to provide a second bias supply voltage. In one embodiment, the bias supply selection circuit includes a voltage monitoring circuit configured to monitor a level of the second bias supply voltage and to provide a control voltage proportional to the level. Additionally, the bias supply selection circuit includes a controllable switching circuit, coupled to the voltage monitoring circuit, configured to select the second bias supply voltage by deactivating the linear regulating device when the control voltage reaches a predetermined value.