A switching apparatus includes three or more series-connected transistors, and it further includes a balancing network. The balancing network includes a resistor network configured to divide a voltage from a voltage source across the series-connected transistors. The resistor network includes at least two resistive legs connected in parallel. In each resistive leg, two or more resistors are connected in series. The balancing network may further comprise at least one capacitive leg of series-connected capacitors connected across the series-connected transistors, and it may further comprise at least one leg of series-connected avalanche diodes connected across the series-connected transistors for overvoltage protection. In example embodiments, the series-connected transistors are JFETs. In other example embodiments, the series-connected transistors may be HEMTs or GaN transistors.

In one embodiment, an impedance matching network includes a variable reactance circuit having fixed reactance components and corresponding switching circuits. Each switching circuit includes a diode and a driver circuit. The driver circuit includes, coupled in series, a biasing current source positioned to provide a bias current to bias the diode, a first switch, a second switch, and a resistor. For each diode of each switching circuit, the control circuit is configured to receive a value related to a voltage drop on the resistor and, based on the value related to the voltage drop, adjust the bias current being provided by the biasing current source.

The disclosure relates to power semiconductor devices in GaN technology. The disclosure proposes an integrated auxiliary gate terminal (15) and a pulldown network to achieve a normally-off (E-Mode) GaN transistor with threshold voltage higher than 2V, low gate leakage current and enhanced switching performance. The high threshold voltage GaN transistor has a high-voltage active GaN device (205) and a low-voltage auxiliary GaN device (210) wherein the high-voltage GaN device has the gate connected to the source of the integrated auxiliary low-voltage GaN transistor and the drain being the external high-voltage drain terminal and the source being the external source terminal, while the low-voltage auxiliary GaN transistor has the gate (first auxiliary electrode) connected to the drain (second auxiliary electrode) functioning as an external gate terminal. In other embodiments a pull-down network for the switching-off of the high threshold voltage GaN transistor is formed by a diode, a resistor, or a parallel connection of both connected in parallel with the low-voltage auxiliary GaN transistor.

A cascode switch comprising a normally-on semiconductor device comprising a gate, a source and a drain, and a normally-off semiconductor device comprising a gate, a source and a drain. The drain of the normally-off semiconductor device coupled to the normally-on semiconductor device, the source of the normally-on semiconductor device coupled to the drain of the normally-off semiconductor device and the gate of the normally-on semiconductor device coupled to the source of the normally-off semiconductor device. The cascode switch further comprises a leakage current clamp coupled across the normally-off semiconductor device, the leakage current clamp circuit configured to prevent the drain of the normally-off semiconductor from going too high due to leakage current.

A power module includes: a GaN transistor, an NMOS transistor, a first capacitor, a first diode and a second diode. The NMOS transistor is electrically connected to the GaN transistor. A negative electrode of the first capacitor is electrically connected to an anode of the first diode and a gate of the GaN transistor. A cathode of the second diode is electrically connected to a gate of the NMOS transistor. The power module further includes a power module control terminal electrically connected to an anode of the first capacitor and an anode of the second diode.

The present disclosure concerns a method and a circuit for controlling first and second switches electrically in series, wherein one or a plurality of crossings of a voltage threshold by a voltage across the first switch cause a conductive state of the second switch.

Devices having one primary transistor, or a plurality of primary transistors in parallel, protect electrical circuits from overcurrent conditions. Optionally, the devices have only two terminals and require no auxiliary power to operate. In those devices, the voltage drop across the device provides the electrical energy to power the device. A third or fourth terminal can appear in further devices, allowing additional overcurrent and overvoltage monitoring opportunities. Autocatalytic voltage conversion allows certain devices to rapidly limit or block nascent overcurrents.

Devices having one primary transistor, or a plurality of primary transistors in parallel, protect electrical circuits from overcurrent conditions. Optionally, the devices have only two terminals and require no auxiliary power to operate. In those devices, the voltage drop across the device provides the electrical energy to power the device. A third or fourth terminal can appear in further devices, allowing additional overcurrent and overvoltage monitoring opportunities. Autocatalytic voltage conversion allows certain devices to rapidly limit or block nascent overcurrents.

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.

The disclosure relates to power semiconductor devices in GaN technology. The disclosure proposes an integrated auxiliary (double) gate terminal and a pulldown network to achieve a normally-off (E-Mode) GaN transistor with threshold voltage higher than 2V, low gate leakage current and enhanced switching performance. The high threshold voltage GaN transistor has a high-voltage active GaN device and a low-voltage auxiliary GaN device wherein the high-voltage GaN device has the gate connected to the source of the integrated auxiliary low-voltage GaN transistor and the drain being the external high-voltage drain terminal and the source being the external source terminal, while the low-voltage auxiliary GaN transistor has the gate (first auxiliary electrode) connected to the drain (second auxiliary electrode) functioning as an external gate terminal. In other embodiments a pull-down network for the switching-off of the high threshold voltage GaN transistor is formed by additional auxiliary low-voltage GaN transistors and resistive elements connected in parallel or in series with the low-voltage auxiliary GaN transistor.