Today’s ATC systems typically rely on sensing DUT’s temperature to close the control loop. However, to react on a temperature change it usually takes a long time for the ATC system to pull the temperature back to the preset value. In this presentation the author will describe a new architecture of DUT ATC system, and with the features available on UltraFLEXplus ’s DCVS instruments, user can calculate the heat power of the DUT in real time and be able to control a Near-DUT-Heater to generate more or less heat based off the electrical power going into the DUT. By doing this, system can maintain the total heat generated by both DUT and extra heater at a constant rate, consequently the temperature shall not fluctuate as much as before without the extra design. As a result, the 3rd party closed-loop ATC system shall be able to maintain DUT temperature much easier and much more accurate.