Apparatus and methods for a bias supply circuit to support power supply including a switched-mode voltage converter cascaded with an n-channel-based linear regulator are provided. In an example, a cascaded power supply system can include a switched-mode DC-to-DC power converter, including an input voltage node, a first stage output voltage node, and a bootstrapped floating bias voltage node, and a linear regulator circuit. The linear regulator circuit can include an n-channel field-effect transistor (NFET) pass transistor, including a drain terminal coupled to the first stage output voltage node, a gate terminal, and a source terminal configured to provide a second-stage output voltage, and a gate driver circuit, including a driver output coupled to the gate terminal of the NFET pass transistor, and a high side supply node configured to receive a bias voltage generated from the bootstrapped floating bias voltage node.