A first bias charge is provided to first bias region at a first level of an electronic device, the first bias region directly underlying a first transistor having a channel region at a second level that is electrically isolated from the first bias region. A voltage threshold of the first transistor is based upon the first bias charge. A second bias charge is provided to second bias region at the first level of an electronic device, the second bias region directly underlying a second transistor having a channel region at a second level that is electrically isolated from the first bias region. A voltage threshold of the second transistor is based upon the second bias charge.