A structure includes a negative temperature coefficient (NTC) resistor for use in gallium nitride (GaN) technology. The NTC resistor includes a p-type doped GaN (pGaN) layer, and a gallium nitride (GaN) heterojunction structure under the pGaN layer. The GaN heterojunction structure includes a barrier layer and a channel layer. An isolation region extends across an interface of the barrier layer and the channel layer, and a first metal electrode is on the pGaN layer spaced from a second metal electrode on the pGaN layer. The NTC resistor can be used as a temperature compensated reference in a structure providing a temperature detection circuit. The temperature detection circuit includes an enhancement mode HEMT sharing parts with the NTC resistor and includes temperature independent current sources including depletion mode HEMTs.