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In this work we have improved the original MG thermalsimulation flow Fig. 1 and developed the fully automatedelectro-thermal analysis scheme.II.METHODOLOGY OF AUTOMATIC COUPLING BETASOFT ANDANALOG DESIGNERThe disadvantages explained before were eliminated innew automatic interaction pattern (see Fig. 2).The original interaction pattern (Fig. 1) was added withnew program named TransPower. On Fig. 2 it is outlinedwith dotted line. Dotted arrows on Fig. 2 show automaticdata transmission carried out by TransPower. ThusTransPower eliminates manual data transmissions andprovides coupled electro-thermal simulation.TransPower acquires information from three types of files:first, files exported by Expedition PCB for BETAsoft andfiles created by BETAsoft simulation engine; second, jobfiles for circuit simulation and results of such a simulation inAnalog Designer; third, binary schematic file from DesignCapture.Electro-thermal simulation procedure of TransPower isexplained below:1. Analog Designer job file review, getting powercomponent list (arrow #1, see Fig. 2);2. forming new job file for Analog Designer simulation toacquire power data (arrow #2, see Fig. 2);3. expanding component list with results of AnalogDesigner simulation (arrow #3, see Fig. 2);4. library component list extraction from BETAsoftlibrary file (exported by Expedition PCB – arrow #4,see Fig. 2);5. association components from power component list(formed on stage 3) and with those from librarycomponent list (formed on stage 4) using schematic filefrom Design Capture (arrow #5, see Fig. 2);6. testing whether component power dissipation acquiredon step 3 differs from one acquired in previous cycle ofthis algorithm by more than accuracy (5 milliwatt), ifyes power of the components is transferred toBETAsoft library file by association formed on step 5(arrow #6, see Fig. 2), if no TransPower will stopsimulation, because it has converged;7. acquisition component temperature from BETAsoftsimulation for component list (arrow #7, see Fig. 2);8. testing whether component temperature acquired onstep 7 differs from one acquired in previous algorithmcycle by more than accuracy (0.2 ºC), if yes24-26 September 2008, Rome, Italytemperature is used to form new job file for AnalogDesigner by association formed on step 5 (arrow #7,see Fig. 2), if no TransPower will stop simulation,because it has converged;9. jump to stage 3.The procedure stops when power or temperature changesare less than accuracy specified in two sequential cycles (seesteps 6 and 8).III. APPLICATION EXAMPLEThe effectiveness of developed scheme Fig. 2 isdemonstrated in the example of power amplifier PCBelectro-thermal design. The circuit schematic of poweramplifier is shown in Fig. 3. It consists of 27 componentsand dissipates the total power about 5 W. Circuit simulationmodel was prepared in Analog Designer. PCB placementand routing were made in Expedition PCB (see Fig. 4),board size is 50x50 mm 2 . Four transistors (Q4, Q5, Q6, andQ7) were placed on the back side of the board (see dottedlines in Fig. 4).Fig. 5 shows the 2D temperature distributions on front andback sides of the board simulated by BETAsoft in originalFig. 1 (a) and improved Fig. 2 (b) schemes.Comparing the results we can see the maximum error27 ºC in one-step thermal simulation carried out by originalMG flow Fig. 1. More accurate results using original patternmight be gained by second cycle of electro-thermalsimulation (the maximum difference in 5-7 ºC), but beingmanual in original pattern it is extremely time-consuming.Time consumption of different simulation runs (see theTable 1) shows the great gain for suggested fully automatedprocedure Fig. 2.Type ofsimulationThermal manual(old version)Electro-thermalmanual(old version)Electro-thermalautomatic(new version)TABLE 1TIME CONSUMPTION OF DIFFERENT SIMULATION RUNSNumber ofiterationMax. temperatureerrorDesigncompletion time1 27 ºC 20 min.2 5-7 ºC 55 min.6 (until converge) 0.2 ºC 22 sec.©EDA Publishing/THERMINIC 2008 77ISBN: 978-2-35500-008-9