Abstract: A gallium nitride (GaN) transistor is provided having a voltage threshold at which the transistor turns ON. The transistor has one or more control electrodes and a gate electrode disposed on a GaN material layer. A bias is applied to the control electrode(s) to prevent shifting of the transistor voltage threshold.

Abstract: A power supply switch for a gallium nitride integrated circuit. The switch includes two or more parallel n-channel transistor switches (FETs). The FETs are controlled by AC gate waveforms of different phases. The use of multiple AC-controlled FETs allows effective DC operation of a bootstrap inverter circuit without requiring a second DC supply voltage.

Abstract: This invention pertains to the design of a novel Gallium Nitride (GaN) High Electron Mobility Transistor (HEMT) with multiple metal contacts to a single contiguous p-GaN island. The invention encompasses various embodiments which introduce innovative mechanisms for threshold voltage (Vth) control through hole injection and removal.

Abstract: A circuit for synchronizing the turn-on/turn-off times of parallel FETs. The circuit includes a plurality of integrated circuits and a synchronizer. Each of the integrated circuits includes a power FET which operates in parallel with the power FETs of the other integrated circuits, and a phase detector. The phase detector receives and compares the phase output signal of the integrated circuit with the phase output signal of another integrated circuit, and provides signals to the synchronizer regarding the relative turn-on times of the power FETs based upon the phase output signals. The synchronizer, in response to the signals from each of the integrated circuits, reduces or increases the turn-on times of the power FETs, thereby synchronizing the turn-on times of the power FETs.

Abstract: A driver circuit for a solid-state relay which includes a split power supply. The positive supply of the split power supply provides a voltage for application to the gate of a power FET for supplying power to a load. The negative supply of the split power supply provides a negative voltage for turning off a control transistor. The control transistor prevents the power FET from conducting power to the load when the driver circuit is turned off. The circuit is particularly adapted for driving a power GaN FET solid state relay. The circuit is provided in a cascaded embodiment to increase the blocking voltage of the solid-state relay.

Abstract: An integrated gate overvoltage protection circuit for protecting the gate of a main field effect transistor (FET). The gate protection circuit includes a blocking FET and a discharge FET connected between the gate and the drain of the main FET. The gate overvoltage protection circuit is configured to turn on both the first FET and the second FET in the event of a fault condition, such that charge from the gate of the main FET is discharged through the first FET and the second FET to the drain of the main FET, thereby protecting the gate of the main FET.

Abstract: A single-ended or differential level-shifting interface for GaN ICs that allows GaN ICs to be controlled with standard low-voltage CMOS level inputs. The logic level shift circuit is based on a resistive network is therefore insensitive to process and temperature variations, making it particularly well suited for implementation in a GaN IC. The resistive network for a single-ended input signal includes a first branch with a voltage divider connected to the input signal. The voltage divider of the first branch provides a level shifted and scaled input signal to the first input of a comparator at the optimal bias point of the comparator. The resistive network also includes a second voltage divider branch with hysteresis for providing a trip voltage to the second input to the comparator, also at the optimal bias point of the comparator. The comparator outputs complementary bipolar level shifted signals corresponding to the input signal.

Abstract: An enhancement mode gallium nitride (GaN) transistor configured to eliminate holes in the gate material under the gate metal. The transistor has four electrodes, namely a drain electrode, a source electrode, a gate electrode and a hole collector electrode. In a preferred embodiment, a negative voltage is applied to the hole collector electrode, attracting holes in the gate material under the gate metal. The attracted holes recombine with electrons supplied by the negative voltage, thereby substantially eliminating the holes.

Abstract: A gate driver circuit which integrates a synchronous bootstrap circuit in an isolation well of an integrated circuit, such that the synchronous bootstrap capacitor connected to the synchronous bootstrap circuit (and to the corresponding switch node of a power converter) can float with the corresponding switch node. Due to this feature, the voltage on one synchronous bootstrapping capacitor can be used to charge the synchronous bootstrapping capacitor of another (higher level) synchronous bootstrap circuit in a separate isolation well connected to a different switch node. As a result, the supply voltages for the synchronous bootstrap circuits in different isolation wells can all be supplied from a single ground referenced supply Vdd.

Abstract: An integrated circuit which includes a GaN FET and a metal-insulator-metal capacitor. The capacitor is fully integrated with a lateral GaN process flow, i.e., the same gate metal layer, field plate metal layer and dielectric layer of the GaN FET are also used to form the bottom plate, insulator and top plate of the capacitor. The top plate is contacted by a conductive via, which extends through the top plate. To increase the voltage breakdown capability of the capacitor of the integrated circuit, a portion of the gate metal layer is formed in the shape of a ring around the conductive via.

Abstract: A physical arrangement of at least two power switches and at least one capacitor in a power loop. At least one of the switches is formed of at least two parallel electronic devices, such as transistors. The arrangement minimizes total power loop impedance and results in approximately equal impedance in each parallel branch of the switch formed of two parallel devices, thereby resulting in approximately equal currents in the switches.

Abstract: A bootstrapping gate driver circuit in which the size of the bootstrap capacitors is reduced. The gate-to-source voltage of the high side (pull-up) FET is pre-driven to an initial voltage (pre-driven voltage) before the bootstrap capacitor releases charge to charge up the gate-to-source voltage of the high side FET. This pre-driven voltage is applied through a pre-driven FET that allows current flow from the supply voltage to charge the gate of the high side FET to the pre-driven voltage. The pre-driven FET is turned on by a turn-on signal that occurs before the bootstrap capacitor releases charge. The pre-driven period (and hence, the pre-driven voltage) is determined from the time that the pre-driven FET begins to turn on, to the time that the bootstrap capacitor starts to release charge.

Abstract: A gallium nitride (GaN) transistor which includes a multi-layer/multi-thickness barrier layer formed of segments of progressively increasing thickness between the gate and drain to progressively increase the 2DEG density in the channel from gate to drain. The GaN gate can be formed on the base barrier layer to produce an enhancement mode device with a positive threshold voltage. By forming the gate over a thicker segment of the barrier layer, a GaN transistor with a less positive threshold voltage, or a depletion mode transistor with a negative threshold voltage, can be produced.

Abstract: A bootstrapping circuit that utilizes multiple pre-charged capacitor voltages and applies the capacitor voltages to the high side FET of a GaN bootstrapping driver. During the pre-charging phase of the bootstrapping driver, multiple capacitors are charged in parallel to the supply voltage. During the driving phase of the bootstrapping driver, the capacitors are connected in series through a number of FETs and connected to the gate terminal of the high side FET of the bootstrapping driver. As a result, the gate-to-source voltage of the high side FET is equal to or greater than the supply voltage during the driving phase, increasing the driving capability of the high side FET and reducing the total required capacitance and die area of the bootstrapping driver.

Abstract: A power supply switch for a gallium nitride integrated circuit. The switch includes two or more parallel n-channel transistor switches (FETs). The FETs are controlled by AC gate waveforms of different phases. The use of multiple AC-controlled FETs allows effective DC operation of a supply switch without requiring a second DC supply voltage.

Abstract: A circuit for synchronizing the turn-on/turn-off times of parallel FETs. The circuit includes a plurality of integrated circuits and a synchronizer. Each of the integrated circuits includes a power FET which operates in parallel with the power FETs of the other integrated circuits, and a phase detector. The phase detector receives and compares the phase output signal of the integrated circuit with the phase output signal of another integrated circuit, and provides signals to the synchronizer regarding the relative turn-on times of the power FETs based upon the phase output signals. The synchronizer, in response to the signals from each of the integrated circuits, reduces or increases the turn-on times of the power FETs, thereby synchronizing the turn-on times of the power FETs.

Abstract: A circuit to enhance the driving capability of conventional inverting bootstrapping GaN drivers. When the inverting driver input is logic high and the driver output is off, the voltage stored on the first bootstrap capacitor for turning on the high side (pull-up) FET of the inverting driver is charged to the full supply voltage using an active charging FET, instead of using a diode or diode-connected FET in a conventional bootstrapping driver. The gate voltage of the active charging FET is bootstrapped to a voltage higher than supply voltage by a second bootstrap capacitor that connects to the inverting driver input, which is at a logic high. The second bootstrap capacitor is charged by an additional diode or diode-connected FET connected to the supply voltage when the inverting driver input is a logic low.

Abstract: An enhancement mode gallium nitride (GaN) transistor with a p-type gate configured to eliminate holes accumulating under the gate metal. The gate has two electrodes, a gate electrode and a hole collector electrode. In a preferred embodiment, a negative voltage is applied to the hole collector electrode, attracting holes accumulating under the gate metal. The attracted holes recombine with electrons supplied by the negative voltage, thereby substantially eliminating the holes.

Abstract: A three-terminal bidirectional GaN FET with a single gate. The device is formed by integrating a single-gate bidirectional GaN FET in parallel with a bidirectional device formed of two back-to-back GaN FETs with a source that is connected to the field plate of the device and does not have a pin-out. Diodes or gate-shorted-to-source FETs are connected between the source without pin-out and the D/S and S/D power terminals of the device. In another embodiment, a single-gate bidirectional GaN FET is provided with diodes or gate-shorted-to-source FETs connected between the substrate and the power terminals of the device.

Abstract: An enhancement mode GaN transistor that includes a multi-region field plate which partially overlaps the gate and partially overlaps a barrier offset layer. The multi-region field plate includes a section of increased height with respect to the channel layer over the portion of the gate nearest the drain contact, and a section of reduced height with respect to the channel layer over the edge or transition of the barrier offset layer, minimizing the peak electric field at the corner of the gate and at the edge or transition of the barrier offset layer.