We downloaded high power ADS module of A2120D040NR1 and tried to DC dias it in ADS. We followed the reference design with 4.7kOhm resisters to the gates and feed 7.4V and 4.8V to gate1 and gate2 separately. Surprisingly the gate current was only several nA and the drain current was several hundreds mA on stage 1 and 5A on stage 2. We reduced the gate voltages to 2V and the drain currents fell to a reasonable level, while the gate currents are still several nA. Please refer to the attached snapshot of ADS simulation.
The question is: According to the datasheet of A2I20D040NR1 and AN1977 page 2, we should see several mA gate current and correspondingly need higher fixture voltage becasue the thermal tracking transistor is acting like a diode. Why do we not see this result in the simulation? Is it because of the module? We also tried the simulation with A2I20D020NR1/A2I20D060NR1 and they show similar results with nA gate current.