Abstract: Circuits and methods of dynamic modulation are disclosed. A dynamic modulator is used to reduce measurable conducted and/or radiated electromagnetic interference (EMI). The dynamic modulator is configured to generate either a set of optimal frequency modulation depths or discrete frequencies or both, and dynamically selects them to use over a series of programmable time durations (dwell time). Together with the utilization of Peak, Average or Quasi-Peak (QP) method of measurement, the dynamic modulator can reduce the spectral amplitude of EMI components, in particular the lower harmonics, to effectively pass regulatory requirements. In alternative embodiments, the dynamic modulator is used in a closed loop system to continuously adjust the frequency and the duty cycle of a PWM signal to reduce conducted and/or radiated EMI.

Abstract: A programmable junction field effect transistor (JFET) with multiple independent gate inputs. A drain, source and a plurality of gate regions for controlling a conductive channel between the source and drain are fabricated in a semiconductor substrate. A first portion the gate regions are coupled to a first gate input and a second portion of the gate regions are coupled to a second gate input. The first and second gate inputs are electrically isolated from each other. The JFET may be programmed by applying a programming voltage to the first gate input and operated by applying a signal to the second gate input.

Abstract: A field effect transistor (FET), in accordance with one embodiment, includes a first semiconductor layer, a first dielectric layer, a second semiconductor layer, a second dielectric layer and a third semiconductor layer. The first dielectric layer may be disposed upon the first semiconductor layer, wherein the first semiconductor layer has a first conductivity type. The second semiconductor layer, having a second conductivity type, may be disposed upon the first dielectric layer. The second dielectric layer may be disposed upon the second semiconductor layer. The third semiconductor layer, having a first conductivity type, may be disposed upon the first semiconductor layer between a first and second portion of the first dielectric layer, a first and second portion of the second semiconductor layer and a first and second portion of the second dielectric layer.

Abstract: A method for fabricating a dual gate structure for JFETs and MESFETs and the associated devices. Trenches are etched in a semiconductor substrate for fabrication of a gate structure for a JFET or MESFET. A sidewall spacer may be formed on the walls of the trenches to adjust the lateral dimension for a first gate. Following the formation of the first gate by implantation or deposition, a buffer region is implanted below the first gate using a complementary dopant and a second sidewall spacer with a thickness that may be the same or greater than the thickness of the first sidewall spacer. Subsequent to the buffer implant, a second gate is implanted beneath the buffer layer using a third sidewall spacer with a greater thickness than the first sidewall spacer.

Abstract: A field effect transistor, in accordance with one embodiment, includes a metal-oxide-semiconductor field effect transistor (MOSFET) having a junction field effect transistor (JFET) embedded as a body diode.

Abstract: A field effect transistor, in accordance with one embodiment, includes a metal-oxide-semiconductor field effect transistor (MOSFET) having a junction field effect transistor (JFET) embedded as a body diode.

Abstract: This invention disclosed a novel method for the reduction the resistance of the drift region by using the minority carrier current injector near the drift region. This current injector is a p-n junction or a p-n junction in connection with a resistor to the gate or the p-n junction in connection with a current limiting device to the gate or a combination of the other devices. The current injecting reduces the chip size especially for the high voltage operations. The deep trench filled with oxide near the current injector is also disclosed as the diverter for redirection of the minority carrier current. The current injectors can also be used to shut off the main current flow of the DMOSFET during reverse bias and injecting minority carriers in the forward bias.

Abstract: This invention disclosed a novel method of fully depleted emitter so that the built-in potential between emitter and the base becomes lower and the charge storage between the emitter and base becomes small. This concept also applies to the diodes or rectifiers. With depleted junction, this result in very fast switching of the diodes and transistors. Another novel structure utilizes the strip base structure to achieve lower on resistance of the bipolar transistor. The emitter region of the strip base can be a normal emitter or depleted emitter.

Abstract: A fast recovery rectifier structure with the combination of Schottky structure to relief the minority carriers during the forward bias condition for the further reduction of the reverse recovery time during switching in addition to the lifetime killer such as Pt, Au, and/or irradiation. This fast recovery rectifier uses unpolished substrates and thick impurity diffusion for low cost production. A reduced p-n junction structure with a heavily doped film is provided to terminate and shorten the p-n junction space charge region. This reduced p-n junction with less total charge in the p-n junction to further improve the reverse recovery time. This reduced p-n junction can be used alone, with the traditional lifetime killer method, with the Schottky structure and/or with the epitaxial substrate.

Abstract: A junction field effect transistor (JFET) with a reduced gate capacitance. A gate definition spacer is formed on the wall of an etched trench to establish the lateral extent of an implanted gate region for a JFET. After implant, the gate is annealed. In addition to controlling the final junction geometry and thereby reducing the junction capacitance by establishing the lateral extent of the implanted gate region, the gate definition spacer also limits the available diffusion paths for the implanted dopant species during anneal. Also, the gate definition spacer defines the walls of a second etched trench that is used to remove a portion of the p-n junction, thereby further reducing the junction capacitance.

Abstract: A method and structure for a composite trench fill for silicon electronic devices. On a planar silicon substrate having a first deposited layer of oxide and a second deposited layer of polysilicon, a trench is etched. Deposition and etch processes using a combination of oxide and polysilicon are used to fabricate a composite trench fill. The trench bottom and a lower portion of the walls are covered with oxide. The remaining portion of the trench volume is filled with polysilicon. The method may be used for junction field effect transistors (JFETs) and metal oxide semiconductor field effect transistors (MOSFETs).

Abstract: JFET and MESFET structures, and processes of making same, for low voltage, high current and high frequency applications. The structures may be used in normally-on (e.g., depletion mode) or normally-off modes. The structures include an oxide layer positioned under the gate region which effectively reduces the junction capacitance (gate to drain) of the structure. For normally off modes, the structures reduce gate current at Vg in forward bias. In one embodiment, a silicide is positioned in part of the gate to reduce gate resistance. The structures are also characterized in that they have a thin gate due to the dipping of the spacer oxide, which can be below 1000 angstroms and this results in fast switching speeds for high frequency applications.

Abstract: A Schottky barrier rectifier, in accordance with embodiments of the present invention, includes a first conductive layer and a semiconductor. The semiconductor includes a first doped region, a second doped region and a plurality of third doped regions. The second doped region is disposed between the first doped region and the first conductive layer. The plurality of third doped regions are disposed in the second doped region. The first doped region of the semiconductor is heavily doped with a first type of dopant (e.g., phosphorous or arsenic). The second doped region is moderately doped with the first type of dopant. The plurality of third doped regions are moderately to heavily doped with a second type of dopant.

Abstract: An etched substrate structure is augmented by conductive material to provide enhanced electrical and/or thermal performance. A semiconductor device substrate comprising active regions defined on a top surface is masked and etched to define a pattern of blind features in a bottom surface of the substrate. A conductive material is then deposited on the surface of the blind features. The replacement of semiconductor material with the conductive material lowers the resistance between the active elements on the top surface and the bottom surface. The blind features may be placed in proximity to parasitic bipolar transistors in order to increase immunity to latchup. During wafer processing, a pattern of grooves aligned opposite to a scribe street pattern may be etched on the wafer back side in order to facilitate the separation of individual devices.

Abstract: A Schottky barrier rectifier, in accordance with embodiments of the present invention, includes a first conductive layer and a semiconductor. The semiconductor includes a first doped region, a second doped region and a plurality of third doped regions. The second doped region is disposed between the first doped region and the first conductive layer. The plurality of third doped regions are disposed in the second doped region. The first doped region of the semiconductor is heavily doped with a first type of dopant (e.g., phosphorous or arsenic). The second doped region is moderately doped with the first type of dopant. The plurality of third doped regions are moderately to heavily doped with a second type of dopant.

Abstract: A multiple doped channel in a multiple doped gate junction field effect transistor. In accordance with a first embodiment of the present invention, a junction field effect transistor (JFET) circuit structure comprises a vertical channel. The vertical channel comprises multiple doping regions. The vertical channel may comprise a first region for enhancement mode operation and a second region for depletion mode operation.

Abstract: An enhancement mode JFET as a switching device in a buck-boost converter circuit combined with a single rectifier diode and an inductor. A control circuit coupled to the gate of the JFET switches the JFET between a current conducting state and a current blocking state. The ratio of converter output voltage to converter input voltage is determined by the ratio of JFET current blocking time to the sum of JFET conduction time and JFET blocking time. This pulse width modulation scheme is thus used to adjust the dc output voltage level.

Abstract: A programmable junction field effect transistor (JFET) with multiple independent gate inputs. A drain, source and a plurality of gate regions for controlling a conductive channel between the source and drain are fabricated in a semiconductor substrate. A first portion the gate regions are coupled to a first gate input and a second portion of the gate regions are coupled to a second gate input. The first and second gate inputs are electrically isolated from each other. The JFET may be programmed by applying a programming voltage to the first gate input and operated by applying a signal to the second gate input.

Abstract: JFET and MESFET structures, and processes of making same, for low voltage, high current and high frequency applications. The structures may be used in normally-on (e.g., depletion mode) or normally-off modes. The structures include an oxide layer positioned under the gate region which effectively reduces the junction capacitance (gate to drain) of the structure. For normally off modes, the structures reduce gate current at Vg in forward bias. In one embodiment, a silicide is positioned in part of the gate to reduce gate resistance. The structures are also characterized in that they have a thin gate due to the dipping of the spacer oxide, which can be below 1000 angstroms and this results in fast switching speeds for high frequency applications.

Abstract: A method for fabricating a dual gate structure for JFETs and MESFETs and the associated devices. Trenches are etched in a semiconductor substrate for fabrication of a gate structure for a JFET or MESFET. A sidewall spacer may be formed on the walls of the trenches to adjust the lateral dimension for a first gate. Following the formation of the first gate by implantation or deposition, a buffer region is implanted below the first gate using a complementary dopant and a second sidewall spacer with a thickness that may be the same or greater than the thickness of the first sidewall spacer. Subsequent to the buffer implant, a second gate is implanted beneath the buffer layer using a third sidewall spacer with a greater thickness than the first sidewall spacer.