This study presents monolithically integrated power circuits, fabricated in a high-voltage GaN-on-Si heterojunction technology. Different advanced concepts are presented and compared with solutions found in the literature. High switching transition slew rates are demonstrated by means of a monolithic power circuit with integrated gate driver. A highly linear temperature sensor is integrated in a GaN-high-electron-mobility transistor (HEMT) power device for the 600 V class and onstate resistance of 53 mΩ. An area-efficient HEMT structure with integrated freewheeling diodes is presented. This structure is applied in a monolithic multilevel converter chip, as well as in a 600 V class half-bridge chip. The multilevel chip is integrated by an advanced printed circuit board embedding technology and tested in inverter operation with a mains voltage output of 120 V RMS. The performance of the half-bridge is demonstrated in a synchronous buck converter operation from 400 to 200 V and with a switching frequency of 3 MHz.

This work presents a quasi-normally-off gallium nitride (GaN) transistor with positive gate threshold voltage based on depletion-mode technology, suitable for gate drivers or logic circuits. Quasi-normally-off behaviour is achieved by the series connection of multiple Schottky diodes in the source path of an initially normally-on transistor. As opposed to conventional approaches, a novel quasi-normally-off gate driver circuit avoids the static shoot-through current path in the driver final stage and ensures a safe blocking state of a d-mode power switch in case of driver failure with only one negative driver supply voltage. For evaluation a hybrid integrated GaN power module is built, comprising a 2.4 A gate driver and 600 V/ 24 A boost converter switching cell. Measurements of pulsed inductive switching up to 274 V/ 12 A show gate voltage rise and fall times of 5.4 ns and 3.8 ns, boost converter switch node transition times as low as 1.6 ns and 1.2 ns, and maximum slew-rates up to 91 V/ns during turn-on transitions, and up to 177 V/ns during turn-off transitions, respectively

This work reports on a 600 V GaN-on-Si power transistor with monolithic integrated gate driver. The circuit is based on Schottky-gate depletion-mode technology and fabricated on a 2×3 mm² chip. The push-pull gate driver stage implements a quasi-normally-off pull-up transistor, fabricated with monolithic integrated series-connected Schottky diodes for positive voltage-level shifting in the source path of a d-mode HEMT. The measured gate-source threshold voltage of the fabricated quasi-normally-off pull-up transistor is +2.7 V as compared to -2.9 V of the normally-on pull-down transistor. Pulsed-IV measurements determine an effective gate driver resistance of around 2. On-wafer measurements of the power transistor show low off-state leakage-currents up to 600 V blocking voltage with high wafer yield and 150 m on-resistance. Finally, inductive-load switching measurements up to 450 V, 14.3 A show maximum switch node slew-rates during turn-on and turn-off transitions as high as 250 V/ns

This paper presents switching operation of a monolithically integrated half-bridge stage in a 600 V-class GaNon- Si technology. The integrated power chip includes two high performance GaN-HEMTs with integrated freewheeling Schottky diodes, on a total chip area of 4x4 mm². Operation of the half-bridge chip is demonstrated in a soft-switching buck converter at switching frequencies up to 3 MHz, input voltages up to 400 V, and output power up to 250 W

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