At PCIM 2019, imec, a world-leading research and innovation hub in nanoelectronics and digital technologies, announced today that it demonstrated a functional GaN half-bridge monolithically integrated with drivers. Mounted on a buck-convertor test board, the chip converts an input voltage of 48 Volt to an output voltage of 1 Volt, with a pulse width modulation signal of 1 MHz. The achievement leverages on imec’s GaN-on-SOI and GaN-on-QST® technology platforms, reducing parasitic inductance and boosting commutation speed.

Today, GaN power electronics are dominated by off-the-shelf discrete components. Half-bridges –common subcircuits in power systems – are fabricated by separate discrete components, either in separate packages, or integrated in one package, especially for the higher voltage ranges. Realizing half-bridges on chip by using GaN-on-Si technology, is very challenging, especially at high voltages. This is because half-bridges designed on GaN-on-Si technology are limited in performance by a back-gating effect that negatively affects the high-side switch of the half-bridge, and switching noise that disturbs the control circuits.

To unlock the full potential of GaN power technology, imec monolithically co-integrated a half-bridge and drivers in one GaN-IC chip. Complemented by low voltage logic transistors, a suite of passive components for low-ohmic and high-ohmic resistors, and a MIM-capacitor, high-end integrated power systems can be realized on one single die.

Imec’s solution builds on imec’s GaN-on-SOI and GaN-on-QST® technology platforms that allow for a galvanic isolation of the power devices, drivers and control logic, by the buried oxide and oxide-filled deep trench isolation. This isolation scheme not only eliminates the detrimental back-gating effect that negatively affects the high-side switch of the half-bridge, but also reduces the switching noise that disturbs the control circuits. With the design of a co-integrated level shifter for driving the high-side switch, a dead-time controller to avoid overlapping gate input waveforms, and an on-chip pulse-width modulation circuit, highly integrated buck and boost convertors can be fabricated.

To further boost the performance of these monolithic integrated power systems, imec aims to extend its platform with additional co-integrated components, such as Schottky diodes and depletion-mode HEMTs.