This SPIE-PW paper by Handel and Sherif presents analytical calculation of the quantum 1/f coherence parameter for HFETs. The research develops mathematical formulas for quantifying the coherence length and coherence parameter that characterize the transition between coherent and conventional quantum 1/f noise regimes in heterostructure field-effect transistors, providing theoretical tools for predicting noise behavior as a function of device geometry, temperature, and bias conditions in advanced semiconductor devices.