The transition frequency of an inverter can vary with the transconductance of its internal transistors as a function of temperature and bias level. To maintain consistent transition frequency across temperatures, and therefore reduce the phase noise variation introduced by the inverter, systems, methods, and circuits are disclosed for biasing the inverter with a temperature varying current such that the transconductance of transistors remains constant across temperatures, while maintaining the lowest possible power consumption to do so. Various embodiments can include using current sources that have proportional-to-absolute-temperature (PTAT) devices.