A voltage doubler circuit supports operation in both a positive voltage boosting mode to positively boost voltage from a first node to a second node and a negative voltage boosting mode to negatively boost voltage from the second node to the first node. The voltage doubler circuit is formed by transistors of a same conductivity type that share a common bulk that is not tied to a source of any of the voltage doubler circuit transistors. A bias generator circuit is coupled to receive a first voltage from the first node and second voltage from the second node. The bias generator circuit operates to apply a lower one of the first and second voltages to the common bulk.