Power Integrations

Vertical gallium nitride (GaN) field effect transistors (FETs) are presented herein. A vertical GaN FET includes cylindrical trench gates arranged in a hexagonal array to form vertical FET channels. At the surface of the vertical GaN FET is a source layer formed in a GaN epitaxial layer and over a GaN substrate. A channel may be formed between the cylindrical gates in the form of a "GaN pillar"; and FET characteristics, including threshold voltage, may be determined, at least in part by a trench nearest neighbor distance. Accordingly, the trench nearest neighbor distance may be selected so that the vertical GaN FET operates as either an enhancement mode or a depletion mode transistor.

A power converter controller with commands based on pulse pattern recognition is described. In one embodiment, a control system for a power converter includes a first switching circuit having a first controller, and a second switching circuit having a second controller. The second controller is configured to generate a pattern of pulses in a transmitted signal U<TX>. The pattern of pulses in the transmitted signal U<TX> corresponds to a predetermined command. The first controller is configured to receive a pattern of pulses in a received signal U<RX>. The first controller includes a pattern filter configured for: comparing the pattern of pulses in the received signal U<RX> with an expected pattern, and, when the pattern of pulses in the received signal U<RX> corresponds to the expected pattern, asserting the predetermined command.

An electrical system includes an insulating substrate; a magnetic coupler comprising coils disposed on opposites sides of the insulating substrate, wherein the coils are at least partially aligned such that a magnetic field generated by current flow through a first of the coils induces an electromotive force in a second of the coils; and a capacitive coupler having plates disposed on opposites sides of the insulating substrate, wherein the plates comprises elongate conductors that are coupled together without forming loops and arranged at least partially beneath or in an interior of the coils of the magnetic coupler on the insulating substrate

The circuits and methods of the present disclosure control the active off-time (high side switch on-time) to ensure the magnetization energy release and resonant capacitor energy release in an asymmetrical half-bridge (AHB) converter finish at the same time and all the stored energy is delivered to the output in each switching cycle. Multiple, parallel, techniques to control the high side switch on-time are illustrated. One is to track the volt-seconds applied during the storage cycle and allow the active release off-time to be limited to the same volt-seconds. A second option is to provide a high side switch on-time that is proportional to the on-time of the low side switch in that switching cycle. A third option is to provide a maximum high side switch on-time that can be programmed to ensure the high side on-time is equal to or smaller than half of the resonant period.

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An interface circuit using mirrored current feedback to reduce input impedance is disclosed herein. According to the teachings herein, the interface circuit includes a current mirror and an input circuit path. Shunt feedback via a return circuit path provides a mirrored current to an interface input thereby reducing an input impedance of the interface circuit. By virtue of shunt feedback, the input impedance of the interface circuit is reduced relative to the impedance of the input circuit path. In this manner, input impedance of the interface circuit may be reduced without changing the impedance of the input circuit path.

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