Chang Soo Kwak

Thermal characterization of MMIC by numerical analysis

Thermal resistances (R/sub th/) of monolithic microwave integrated circuits (MMIC) for the Ka-band communications satellites transponder, which is being developed by ETRI, have been calculated by the finite element method (FEM). Through the analyses of finite element models with or without selective metal layers, additional MMICs thermal characteristics have been found and a reasonably simplified finite element modeling method for MMIC has been introduced. Parametric studies on the relations between the total gate width or the power dissipation and the thermal resistance were performed. With the parametric study results, an equation for calculating the thermal resistance of an MMIC showing error of 6% or less has been developed.

Numerical analysis and IR scan test for thermal resistance of GaAs MMIC in a communications satellite

Thermal resistance of a 3 GHz power amplifier MMIC has been calculated with finite element (FE) analyses. Through comparative FE analyses it has been found that a carrier for infrared (IR) scan test should have high thermal conductivity if it is for measuring thermal resistance of an MMIC only. IR scan results showed that the FE analysis provided temperature distribution quite close to the real and, also, that IR scans could not measure the maximum channel temperature because of not enough resolution. Consequently it has been proved that the FE method can provide more realistic thermal resistance of an MMIC than IR scan test when the gate length is smaller than IR scanners resolution as well as when the gate is screened by an airbridge.