Apparatus and methods are disclosed for providing a bias. A main diode has first and second terminals that connect to a high voltage (HV) line and to an HV regulated line, respectively. The main diode provides a voltage on the HV regulated line lower than a voltage of the HV line. A first current mirror provides a first current. The current mirror connects to the first terminal of the main diode and the HV regulated line. A second current mirror provides a second current. The second current mirror connects to the HV line, the first current mirror, and a low-voltage (LV) line. An impedance is between the LV line and the HV regulated line. A voltage differential between the HV regulated line and the LV line below a low-voltage threshold, and a voltage differential between the HV regulated line and the HV line above the low-voltage threshold are provided.