Detailed analysis of device behaviour on the zero-temperature coefficient (ZTC) points for microwave GaAs based high-electron mobility transistor is presented by means of on-wafer measurements over the temperatures between -40 and 150 degrees C. This zero temperature coefficient points found not only in the transfer and transconductance curve but also in intrinsic transconductance g(mo), output conductance g(ds), small signal gain S-21, and minimum noise figure NFmin also exhibits ZTC. It is found that the zero temperature coefficients points are impacted by both threshold voltage and drain bias. The transfer current base, ZTCI(ds) moved from 0.1 V to -0.2 V of V-gs trace and transconductance based, ZTC(gm) moved from -0.3 V to -0.6 V of V-gs trace with the drain bias, V-ds varies from 1 V to 5 V. The behaviour of some intrinsic equivalent circuit parameters along with cut-off frequency, f(t) at both ZTC bias points opens some crucial insight and opportunities in microwave device design for low and high temperature applications.