Various aspects of the disclosure are directed to circuitry that may be used to shunt current. As may be consistent with one or more embodiments a first circuit has a plurality of alternating p-type and n-type semiconductor regions with respective p-n junctions therebetween, arranged between an anode end and a cathode end. A second ( e.g ., bypass) circuit is connected to one of the alternating p-type and n-type semiconductor regions, and forms a further p-n junction therewith. The second circuit operates to provide carrier flow, which influences operation of the first circuit.