Low gate drive IGBT enabling direct control through Digital Isolator power

Known to the power industry, there is an increasing functional safety need to isolate delicate control systems from the violent world of the Insulated Gate Bipolar Transistor (IGBT), which has resulted in a growing demand for Digital Isolators. This is where the gate control signal for the IGBT can be coupled across a dielectric barrier, while the barrier itself is capable of withstanding high working voltages and surge events. Preventing the formation of a complete integrated system solution for the end customer is the fact that while the control signal can be coupled across the isolation barrier - the transient power needed to drive the IGBT gate cannot. To solve that problem, this paper describes the development of an innovative IGBT architecture that targets the 1200V voltage node, has a first silicon V CE (SAT) = 2.7V at JC=10Amm −1 , provides latch-up immunity, and critically has gate drive capacitances that are over two orders of magnitude smaller, at 0.58pF for every Amp of IGBT current, relative to conventional IGBT architectures that report values in the range of 70 – 150pFA −1 at 25°C. This low input capacitance opens the door for the gate of this IGBT to be directly powered by integrated magnetically coupled isolation coils. For future work, further optimization of the V CE (SAT), and transient switching times are required.