An apparatus comprising: a first supply node; a second supply node; a first transistor coupled to the first supply node, the first transistor is to provide a first current which is complementary to absolute temperature (CTAT); a second transistor coupled to the first supply node, the second transistor is to provide a second current which is proportional to absolute temperature (PTAT); a resistive device coupled in series at a node with the first and second transistors, and coupled to the second supply node, wherein the node is to sum the CTAT and the PTAT currents.