Abstract: A turn-off circuit for a semiconductor switch includes an element having a variable resistance coupled to a control input of the semiconductor switch, a circuit for generating a control-input reference signal, and a control circuit coupled to adjust a resistance of the element having a variable resistance in response to the control-input reference signal in a closed control loop in order to turn off the semiconductor switch.

Abstract: An energy transfer element that provides galvanic isolation in a power controller is disclosed herein. A magnetic core assembly has an aperture. A first power winding is positioned within the magnetic core assembly. A first communication winding and a second communication winding are positioned within the aperture such that both the first and second communication windings are perpendicular to the first power winding. The magnetic flux density produced by current in the first power winding is perpendicular to the magnetic flux density produced by current in the first communication winding and the second communication winding For a power controller having an input-referenced controller and an output-referenced controller, the energy transfer element provides galvanic isolation between the controllers because the communication windings are electrically insulated from each other and from the magnetic core assembly.

Abstract: Magnetic saturation detectors for power converters are presented herein. An energy transfer element has an input power winding wrapped around a center post. Single or multiple transverse windings are positioned perpendicular to the input power winding and coupled to receive a transverse current that provides a transverse magnetic flux density within the energy transfer element. The transverse magnetic flux density produces a transverse voltage waveform. A voltage detection circuit is configured to receive the transverse voltage waveform and detect a change in the sign of the slope of the transverse voltage waveform. The change in the sign of the slope indicates magnetic saturation. The voltage detection circuit is configured to detect an occurrence of an extremum in the transverse voltage waveform. The extremum indicates the change in the sign of the slope.

Abstract: A power converter, comprising an energy transfer element, an output of the power converter, a power switch, an active clamp circuit, and a first controller. The active clamp circuit comprising a capacitance, a steering diode network coupled to the capacitance and configured to transfer a charge to the capacitance, a clamp switch coupled to the capacitance and configured to transfer the charge stored in the capacitance to the energy transfer element, and an offset element coupled to the clamp switch and configured to provide a path to discharge a capacitance associated with the clamp switch. The first controller configured to output a clamp drive signal to control the turn on and turn off of the clamp switch and a primary drive signal to control the turn on and turn off of the power switch.

Abstract: A power converter comprising an energy transfer element is coupled between an input of the power converter and an output of the power converter. A cascode circuit generates a first sense signal and a second sense signal. A controller controls the switching of the cascode circuit to transfer energy from the input of the power converter to the output of the power converter. The controller comprising a current sense circuit generates a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal. A control circuit generates a control signal in response to the current limit signal and the overcurrent signal. A drive circuit comprising a first stage gate drive circuit generates a drive signal in response to the control signal to reduce EMI, and a second stage of gate drive circuit to enable accurate current sensing of the cascode circuit.

Abstract: A current matching circuit includes a plurality of LED driver circuits. A current to voltage converter circuit is coupled to the plurality of LED driver circuits to generate a plurality of voltage signals. Each one of the plurality of voltage signals is representative of a respective output current through a corresponding one of the plurality of LED driver circuits. A comparison circuit is coupled to the current to voltage converter circuit to compare the plurality of voltage signals. An adjustment circuit is coupled to the comparison circuit and the plurality of LED driver circuits. The adjustment circuit is configured to trim the plurality of LED driver circuits in response to the comparison circuit such that each respective output current through the plurality of LED driver circuits is substantially equal.

Abstract: A controller for a power converter comprising a drive signal generator and drive strength control and a variable strength multi-stage gate driver. The drive signal generator and drive strength control outputs a drive signal to control switching of a power switch and a strength signal to control drive strength of the power switch. The variable strength multi-stage gate driver is configured to turn ON the power switch in response to the drive signal with a first drive strength then a second drive strength when the strength signal is not asserted. The variable strength multi-stage gate driver is configured to turn ON the power switch in response to the drive signal with a third drive strength then the second drive strength when the strength signal is asserted. The second drive strength is stronger than the first drive strength and the first drive strength is stronger than the third drive strength.

Abstract: Systems, devices, and methods for active discharge of an electric drive system for a vehicle includes an inverter having at least one phase leg, wherein a first of the phase legs includes a first power switch, a dc/dc converter configured to generate an internal supply voltage that is regulated with respect to a voltage on a rail , and a gate drive channel configured to drive the first power switch into conductance by applying a relatively high voltage difference during operation of the vehicle and to continue the driving of the first power switch with a relatively lower voltage difference after a signal indicating shut-down or fault. The dc/dc converter is configured to generate the internal supply voltage to have either a relatively high voltage difference with respect to the voltage on the rail or a relatively lower voltage difference with respect to the voltage on the rail.

Abstract: An electric drive system for a vehicle includes an inverter having at least one phase leg, wherein a first of the phase legs includes a first power switch; an internal voltage supply configured to generate an internal supply voltage regulated with respect to a voltage on a rail and a second voltage, wherein the internal voltage supply is configured to reduce a voltage difference between the internal supply voltage and the second voltage in response to a signal indicating a shut-down or a fault; and a gate drive channel configured to drive the first power switch into conductance by applying the voltage difference between the internal supply voltage and the second voltage between a control terminal and a main terminal of the power switch, gate drive channel configured to continue the driving of the first power switch for a time duration after the signal indicating the shut-down or the fault.

Abstract: Capacitance networks for enhancing high voltage operation of high electron mobility transistors (HEMTs) are presented herein. A capacitance network, integrated and/or external, may be provided with a fixed number of capacitively coupled field plates to distribute the electric field in the drift region. The capacitively coupled field plates may advantageously be fabricated on the same metal layer to lower cost; and the capacitance network may be provided to control field plate potentials. The potentials on each field plate may be pre-determined through the capacitance network, resulting in a uniform, and/or a substantially uniform electric field distribution along the drift region.

Abstract: An auxiliary converter coupled to an output of a main power converter comprising an auxiliary switch, a timing circuit, and an energy transfer element. The auxiliary switch coupled to the output of the main power converter. A timing circuit coupled to receive a control signal from a controller of the main power converter, wherein the controller regulates the output of the main power converter, the timing circuit configured to output an auxiliary drive signal to control switching of the auxiliary switch in response to the control signal. The energy transfer element coupled to the auxiliary switch, wherein the energy transfer element is configured to transfer energy from the output of the main power converter to a supply of the controller, the supply provides operational power for the controller of the main power converter.

Abstract: An enhancement mode metal insulator semiconductor high electron mobility transistor (HEMT) is presented herein. By using a polarization stack to replace the traditional barrier layer, a thinner barrier layer (e.g., a thinner layer of AlGaN) may be formed during fabrication to effectuate a low-sheet-resistance two-dimensional electron gas. Advantageously, the thinner (.i.e., less-than-ten nanometers) barrier layer mitigates reactive ion etching (RIE) induced surface damage. This in turn allows the formation of a recessed gate. Additionally, a dual dielectric gate stack may be deposited to further reduce leakage currents and to improve subthreshold slope.

Abstract: Coupled polysilicon guard rings for enhancing breakdown voltage in a power semiconductor device are presented herein. Polysilicon guard rings are disposed above the power device drift region and electrically coupled to power device regions (e.g., device diffusions) so as to spread electric fields associated with an operating voltage. Additionally, PN junctions (i.e., p-type and n-type junctions) are formed within the polysilicon guard rings to operate in reverse bias with a low leakage current between the power device regions (e.g., device diffusions). Low leakage current may advantageously enhance the electric field spreading without deleteriously affecting existing (i.e., normal) power device performance; and enhanced electric field spreading may in turn reduce breakdown-voltage drift.

Abstract: A controller comprising a driver interface referenced to a first reference potential, a drive circuit referenced to a second reference potential, and an inductive coupling. The driver interface comprises a first receiver configured to compare a portion of signals having a first polarity on the first terminal of the inductive coupling with a first threshold, and a second receiver configured to compare a portion of signals having a second polarity on the second terminal of the inductive coupling with a third threshold. The drive circuit comprises a first transmitter configured to drive current in a first direction in the second winding to transmit first signals, and a second transmitter configured to drive current in a second direction in the second winding to transmit second signals, the second direction opposite the first direction.

Abstract: A power conversion system comprising a system controller configured to generate an input signal in response to a system input and a switch controller coupled to the system controller, the switch controller configured to control a power switch. The switch controller comprises a driver interface configured to receive the input signal that indicates whether the power switch should be ON or OFF, the driver interface further configured to transmit one or more current pulses across a galvanic isolation using an inductive coupling. The driver interface further comprises a first local power supply configured to increase an output voltage of the first local power supply when a transmission of current pulses is imminent.

Abstract: A method for making an energy transfer element provides a magnetic core having a gap in a magnetic path, positions in the gap magnetizable material that produces an initial flux density, cures the suspension medium, and wraps one or more power windings around the magnetic path. When the magnetizable material is magnetized, a flux density produced by the magnetized material is offset from the initial flux density. The magnetizable material comprises a mixture of a suspension medium that includes uncured epoxy and magnetizable particles. The magnetizable particles are capable of permanent magnetic properties when magnetized. The particles of magnetic material having magnetic permeability of at least 1000?o. The particles of magnetic material that have a magnetic permeability of at least 1000?o and the particles of magnetizable particles are uniformly distributed in the suspension medium.

Abstract: An energy transfer element comprises a magnetic core having a gap in a magnetic path. Magnetizable material producing an initial flux density is positioned in the gap. One or more power windings is wrapped around the magnetic path. When the magnetizable material is magnetized the flux density produced by the magnetized material is offset from the initial flux density. The core is a toroid magnetic core or is comprised of two core pieces. The magnetizable material is an unmagnetized magnet or a mixture of a suspension medium comprising uncured epoxy and magnetizable particles. The magnetizable particles are selected from a group comprising Neodymium Iron Boron (NdFeB) based materials or Samarium Cobalt (SmCo) based material.

Abstract: An energy transfer element comprises a U-shaped core of powder core, the U-shaped core having two legs and a gap in a magnetic path, a bar comprising magnetizable material positioned in the gap such that the magnetic core and magnetizable material form a rectangular toroid, and one or more power windings wrapped around the magnetic path. The magnetizable material is capable of being magnetized. When the magnetizable material is unmagnetized, the magnetizable material has an initial flux density. When the magnetizable material is magnetized, the flux density produced by the magnetized material is offset from the initial flux density. The magnetizable material is an unmagnetized magnet or a suspension medium such as epoxy with magnetized magnetizable particles and powder core. The magnetizable particles are selected from a group comprising Neodymium Iron Boron (NdFeB) based materials or Samarium Cobalt (SmCo) based material.

Abstract: A method of forming one or more contact regions in a high-voltage field effect transistor (HFET) includes providing a semiconductor material, including a first active layer and a second active layer, with a gate dielectric disposed on a surface of the semiconductor material. A first contact to the semiconductor material is formed that extends through the second active layer into the first active layer, and a passivation layer is deposited, where the gate dielectric is disposed between the passivation layer and the second active layer. An interconnect is formed extending through the first passivation layer and coupled to the first contact. An interlayer dielectric is deposited proximate to the interconnect, and a plug is formed extending into the interlayer dielectric and coupled to the first portion of the interconnect.

Abstract: A controller for a power converter comprising a drive signal generator and drive strength control and a variable strength multi-stage gate driver. The drive signal generator and drive strength control outputs a drive signal to control switching of a power switch and a strength signal to control drive strength of the power switch. The variable strength multi-stage gate driver is configured to turn ON the power switch in response to the drive signal with a first drive strength then a second drive strength when the strength signal is not asserted. The variable strength multi-stage gate driver is configured to turn ON the power switch in response to the drive signal with a third drive strength then the second drive strength when the strength signal is asserted. The second drive strength is stronger than the first drive strength and the first drive strength is stronger than the third drive strength.