A Pulse Current Source for Transient Thermal Impedance Measurement With Low Nonthermal Switching Transient Effects

The accurate evaluation of thermal characteristics is crucial for the high-reliability operation of semiconductor devices. During transient thermal impedance measurements (TTIM), the nonthermal switching transient effects (NSTE) between the high-power heating phase and the low-power measurement phase obscure the early-stage heat dissipation characteristics of the device, causing a delay in junction temperature (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub>) measurement and compromising the accuracy of TTIM. To address this issue, the proposed current source provides an additional current path during nonthermal switching transients, which autonomously deactivates without external control circuits. The accelerated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> measurement enabled by this method effectively reduces thermal estimation errors. First, a detailed analysis reveals the underlying mechanisms of NSTE. Then, a novel pulse current source is proposed, integrating a transient compensation circuit to eliminate adjustment delay and reduce parasitic capacitance charging time. Finally, the effectiveness of the proposed method is validated on the Simcenter MicReD Power Tester platform. Experimental results indicate that the proposed method reduces <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">j</sub> measurement delay from 500 μs to below 100 μs under milliamp-level current conditions. It can reduce the relative error of the steady-state thermal resistance by an order of magnitude for low-capacity power devices.