A circuit including control logic; and configurable impedance logic, operatively coupled to the control logic, comprising a configurable transistor structure operative to selectively change from a high impedance mode where the configurable transistor structure is configurable as a plurality of series connected diodes having their cathodes coupled together, and a low impedance mode where the configurable transistor structure is configurable to include a plurality of cascoded transistors. The circuit may further include at least one control signal line from the control logic to the configurable impedance logic, where the control signal line is operative to provide a control signal for configuring the configurable impedance logic.