Performance characterisation of a microwave transistor for the maximum output power and the required noise

The performance characterisation of a microwave transistor is carried out rigorously based on the linear circuit and noise theories, subject to the maximum output power and the predetermined input termination. For this purpose, the transducer gain G_T is maximised analytically with respect to the input termination Z_S for the output port matched, provided that Z_S meets the noise figure requirement F_req ⩾ F_min remaining within the unconditionally stable working area (USWA). Analysis is made in the z-parameter domain which facilitates a single unique crescent conditional stability configuration to replace the eight different, rather complicated stability configurations in the S-parameter domain. Finally, the compromise relations between the gain, noise figure for the output port matched are obtained with typical design configurations depending on the operation conditions of a selected high technology transistor. Incompatible noise and gain requirements can also be observed in their design configurations. Furthermore the cross-relations among the bias condition (VDS, IDS) and ingredients of the performance {F_req ⩾ F_min, V_out = 1, G_T ⩽ G_Tmax} triplets and together with their terminations {Z_S, Z_L = Z^*_out(Z_S)} can be formed basis for "Performance Data Sheets" of microwave transistors to be employed for the amplifier designs of maximum output power and low noise.