216results about How to "Reduce conduction loss" patented technology

The invention belongs to the technical field of crystal growth, and provides a low-resistivity silicon carbide single crystal growth method and system and a single crystal, silicon carbide powder is uniformly paved at the bottom of a graphite crucible, metal carbide material particles are uniformly paved on the surface of the silicon carbide powder, and silicon carbide seed crystals are adhered to the top of the graphite crucible; the graphite crucible is sealed, and the interior of the graphite crucible is vacuumized; heating the graphite crucible subjected to vacuumizing treatment, filling carrier gas into the graphite crucible, then slowly replacing the carrier gas with doped source gas, slowly increasing the growth pressure to a set pressure, and growing a buffer layer; after the growth of the buffer layer is completed, changing the growth condition to grow the heavily doped silicon carbide single crystal; and after the growth of the crystal is completed, cooling the graphite crucible subjected to vacuumizing treatment, so that the crystal is naturally cooled, and the low-resistivity silicon carbide single crystal is obtained. The doping concentration of the silicon carbide single crystal can be improved, and the resistivity of the silicon carbide material can be reduced.

According to the SGT MOSFET of the Low-k material and the preparation method of the SGT MOSFET, a gate insulating layer of the SGT MOSFET is deposited by adopting the Low-k material based on carbon-doped silicon oxide, and an oxide layer on the side wall of a shielding gate adopts an ONO structure, so that on one hand, the capacitance effect of a device can be reduced through the Low-k material under the condition that the physical thickness of the insulating layer is kept unchanged and electric leakage is not influenced, and the performance of the device is improved; the performance of the device is improved; and on the other hand, the compactness of the silicon nitride layer is high, and the side wall and the bottom of the shield gate polycrystalline silicon are protected by the silicon nitride layer, so that the on resistance of the device is further reduced and the conduction loss of the device is reduced by improving the doping concentration of the epitaxial layer on the basis of not reducing the breakdown voltage. Meanwhile, by controlling the depth of the oxide layer and the silicon nitride layer which are etched on the side wall of the groove, the silicon nitride layer is far away from the grid polycrystalline silicon, and the reliability of the device is improved.

The invention provides a control method of a power conversion circuit, power conversion equipment and a power supply system. The control method can obtain a target inner phase shift duty ratio corresponding to the highest voltage matching degree according to the real-time direct-current voltage and the real-time alternating-current voltage, and obtain a reference outer phase shift duty ratio according to the real-time direct-current voltage, the real-time alternating-current voltage, the target inner phase shift duty ratio, preset target alternating-current power and power transmission constraint conditions. Adjusting a reference outer phase shift duty ratio according to the real-time alternating current and a preset target alternating current to obtain a target outer phase shift duty ratio, and obtaining a target switching frequency according to the real-time direct current voltage, the real-time alternating current voltage, the target inner phase shift duty ratio, the reference outer phase shift duty ratio, the target alternating current power and a switching frequency constraint condition, and controlling power transmission of the power conversion circuit according to the target switching frequency, the target inner phase shift duty ratio and the target outer phase shift duty ratio. According to the method, the transmission efficiency of the power conversion circuit can be improved, and the current stress can be reduced.

The invention provides an electric field enhancement type shield gate MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), which comprises a substrate, an epitaxial layer formed on the substrate, a gate trench formed on a cellular region on the epitaxial layer, and a first gate dielectric layer formed at the bottom of the gate trench and a first polycrystalline silicon layer located in the first gate dielectric layer, a P-type epitaxial layer is formed on the first gate dielectric layer and the first polycrystalline silicon layer, and an isolation dielectric layer is formed on the P-type epitaxial layer; a second gate dielectric layer is formed on the side wall of the residual gate trench, and a second polycrystalline silicon layer is formed in the residual gate trench; a well region and a source region of a cellular region are formed on the epitaxial layer, and a contact hole dielectric layer is formed on the epitaxial layer; and contact holes communicated with the well region are formed on the contact hole dielectric layer and the epitaxial layer below the contact hole dielectric layer. By adding the shield grid P-type epitaxial layer, the electric field intensity in the middle of the drift region is effectively improved, the breakdown voltage is improved, and meanwhile, the conduction loss can be further reduced by adjusting epitaxy.

The utility model provides a miniature POCT (Point of Care Testing) detection device. Miniature POCT detection equipment comprises a control module, a shell and a top cover, the shell is used for containing a reaction tube, a top cover heating module is arranged in the top cover, and the top cover heating module is configured to be in contact connection with a reaction tube cover when the shell and the top cover are closed and can heat the reaction tube cover during contact connection. According to the equipment, the top cover heating module is arranged, so that the reaction tube cover can be heated. Therefore, the temperature of the upper half part of the reaction tube can be adjusted, and when the lower half part of the reaction tube is heated to react by the heating module and water vapor evaporated in the reaction tube rises to the reaction tube cover, the water vapor cannot be pre-cooled and condensed on the reaction tube cover due to the small difference between the temperature of the reaction tube cover and the reaction temperature of the reaction tube; therefore, the precision and the accuracy of the equipment during the experiment are integrally improved.

The invention provides a varied doping high-reliability planar gate silicon carbide VDMOS and a preparation method thereof, and the method comprises the steps: depositing metal on the lower side surface of a silicon carbide substrate, and forming a drain metal layer; epitaxially growing on the upper side surface of the silicon carbide substrate to form a drift layer; a barrier layer is formed, etching and ion implantation are carried out, and a first N-type region, a second N-type region and a P-type well region are formed; a barrier layer is formed again, etching and ion implantation are carried out, and an N-type source region is formed; a barrier layer is formed again, etching and ion implantation are carried out, and a third N-type region is formed; a barrier layer is formed again, and a gate dielectric layer is formed through etching and deposition; and re-forming a barrier layer, etching, depositing metal, forming a gate metal layer and a source metal layer, and removing the barrier layer to complete preparation. The transverse layout of the on-resistance of the device is accurately controlled, so that the current is uniformly distributed in the device, heat concentration is avoided, and the reliability of the device is improved.

The invention discloses a planar gate dual-control electrode 4H-SiC composite transistor structure which comprises a plurality of cell structures connected in parallel, each cell structure comprises an n buffer layer on a 4H-SiC n + substrate, an n-drift region, an n carrier expansion layer and p body regions in the two sides of the n carrier expansion layer, each p body region is of a mesa structure, an n + source region and a p + region are arranged in the upper part and the lower part, and a gap is formed between the n + source region and the p + region; gate oxide layers and polycrystalline silicon layers are arranged on the surfaces of the n carrier expansion layer, the p body regions on the two sides and part of the n + source region; a plane grid G is arranged on the surface of the polycrystalline silicon layer; a source S is arranged on the surface of the n + source region; a base B is arranged on the surface of the p + region; a drain electrode D is arranged on the back surface of the 4H-SiC n + substrate; the cellular structure is in bilateral symmetry with the planar grid G as the axis, equivalently, the VDMOS and the BJT are connected in parallel, the VDMOS is located in the center, and the BJT is located on the outer side. According to the invention, the conduction loss of the device can be reduced, the anti-short-circuit capability is improved, and the influence of a body diode is eliminated.

The invention relates to a switching tube driving voltage control circuit and method and a power converter. The switch tube driving voltage control circuit in one aspect is used for being connected with each switch tube in the power converter and comprises a sampling circuit, a first feedback circuit, a power supply circuit and a driving circuit, and the first sampling circuit is used for sampling alternating current side voltage of a power conversion circuit to obtain target sampling voltage; the first feedback circuit is used for processing according to a first mapping relation based on the target sampling voltage to obtain a target feedback voltage; the power supply circuit is used for outputting target power supply voltage based on the target feedback voltage; and the driving circuit is used for outputting target driving voltage based on the target power supply voltage so as to drive conduction of the switching tube. By adopting the switching tube driving voltage control circuit, the conversion efficiency of the power converter can be improved.

The invention discloses a field effect transistor, which comprises a drain electrode positioned on a bottom layer; the substrate is located on the drain electrode; the semiconductor layer of the first conductive type is located on the substrate; a source region of the first conductivity type on the semiconductor layer of the first conductivity type; a gate trench extending from the source region of the first conductivity type into the semiconductor layer of the first conductivity type, the gate trench including a gate electrode and a shield gate electrode; the insulating dielectric layer is arranged on the gate trench and the source region of the first conductivity type; a source electrode having a first portion in Schottky contact with the semiconductor layer of the first conductivity type and a second portion in ohmic contact with the source region of the first conductivity type; wherein the semiconductor layer of the first conductivity type is divided into three regions from top to bottom, the doping concentration of the second doped region is gradually changed or uniformly doped, and the doping concentration is higher than that of the other two regions. Distribution of an electric field can be optimized, so that the electric field is distributed in a rectangular shape, voltage resistance of the device is improved, and on resistance of the device is reduced.

The invention discloses a semiconductor structure and a forming method thereof. The structure comprises a substrate; the storage gate structure is located on part of the surface of the substrate, the storage gate structure comprises a tunneling oxide layer, a charge trapping layer located on the tunneling oxide layer, a barrier layer located on the charge trapping layer and a gate layer located on the surface of the barrier layer, and the dielectric constant of the barrier layer is larger than that of the charge trapping layer; and the source doped region and the drain doped region are respectively positioned in the substrate at the two sides of the storage gate structure, so that the diffusion of electrons in the gate layer into the charge trapping layer is reduced, the back gate electron injection effect is favorably inhibited, and the performance of the storage device is favorably improved.

The invention provides a modulation mode switching synchronous rectification soft switching buck type constant voltage power supply which comprises an input filter circuit, a power inductor L1, an output filter circuit, a main switch tube Q1, a synchronous rectification tube Q2 and a control circuit. The left end of the power inductor L1 is connected to the source electrode of the main switch tube Q1 and the drain electrode of the synchronous rectifier tube Q2, the right end of the power inductor L1 is connected to the positive electrode of the output capacitor, the drain electrode of the main switch tube Q1 is connected to the positive electrode of the input capacitor, and the source electrode of the synchronous rectifier tube Q2 is connected to a reference ground through a power inductor current sampling resistor RS1; and the control circuit respectively controls the on-off states of the main switch tube Q1 and the synchronous rectifier tube Q2 so as to realize zero-voltage conduction of the synchronous rectifier tube Q2. Through the characteristics of different modulation modes, light-load and heavy-load modulation mode switching and synchronous rectifier tube soft switching are realized, and the loss of the switching power supply under different conditions is reduced.

The invention discloses a hybrid half-frequency modulation method, system and device for a dual-active bridge DC-DC converter and a medium. The method comprises the following steps: judging a working mode of a current working point of the dual-active bridge DC-DC converter according to the transmission power p, the input voltage Vin and the output voltage Vo of the dual-active bridge DC-DC converter; the modulation type is determined according to the working mode of the current working point of the dual-active bridge DC-DC converter, and the modulation type comprises three-phase shift (TPS) modulation, secondary side half-frequency modulation, primary side half-frequency modulation and double-side half-frequency modulation; according to the method, the system, the equipment and the medium, the problems of large inductive current stress and low efficiency of the DAB converter in a wide voltage range and a full power section can be effectively solved.

The invention provides a drain feedback and source feedback combined forced resonance flyback constant current power supply, which relates to the technical field of switching power supplies and comprises a transformer T1, an RCD clamping circuit, a first switching tube Q1, a second switching tube Q2 and a control circuit, and the control circuit is used for providing a first control signal and a second control signal to respectively control the switching state of the first switching tube and the switching state of the second switching tube so as to realize zero-voltage conduction of the first switching tube. Through the characteristic of the forced resonance auxiliary circuit, the characteristic of soft switching of the first switching tube is realized, and the switching loss is greatly reduced; meanwhile, the mode of combining drain electrode feedback and source electrode feedback is used, the size of the converter is reduced, the production cost is reduced, and the sampling precision is improved.

The invention provides a driving circuit, a motor driving chip, a motor control device and electric equipment. The driving circuit comprises a power device unit and a power device driving circuit, wherein the power device unit comprises a first silicon-based power device, a first silicon carbide power device, a second silicon-based power device and a second silicon carbide power device; the power device driving circuit is used for driving the first silicon carbide power device to be switched on in a switch-on stage and a switch-off stage of the power device unit and driving the first silicon-based power device to be switched on in the switch-on stage of the power device unit when the power device unit is used as an output loop of a power signal; and when the power device unit is used as an input loop of a power signal, the second silicon carbide power device is driven to be switched on in the switching-on stage and the switching-off stage of the power device unit, and the second silicon-based power device is driven to be switched on in the switching-on stage of the power device unit. The driving circuit can reduce the switching loss of the power device and prolong the service life of the power device.

The invention provides a driving circuit for driving an input power tube in a charge pump, the input power tube of the charge pump is an NMOS tube, conduction loss is reduced, a source electrode of the input power tube receives input voltage, and a drain electrode of the input power tube is coupled to a first end of a flying capacitor; a grid electrode of a high-end source-following NMOS tube of the driving circuit receives adjustable reference voltage, a drain electrode of the high-end source-following NMOS tube is coupled to an output end of the charge pump, a source electrode of the high-end source-following NMOS tube is coupled to a drain electrode of a low-end source-following NMOS tube, a source electrode of the low-end source-following NMOS tube is coupled to a drain electrode of a pull-down NMOS tube, a grid electrode of the low-end source-following NMOS tube is coupled to a grid electrode of the pull-down NMOS tube, and the grid electrode of the pull-down NMOS tube is coupled to the output end of the charge pump. The grid electrode of the pull-down NMOS tube further receives an input power tube control signal through the driver, the source electrode of the pull-down NMOS tube is coupled to the first end of the flying capacitor, and the drain electrode of the pull-down NMOS tube is further coupled to the grid electrode of the input power tube. And the driving circuit directly receives the input voltage, so that the area of the charge pump is reduced.

The invention discloses a frequency multiplication soft switching control method and controller for a six-tube Buck-Boost converter, and belongs to the field of power electronic conversion and control, and the method comprises the steps: enabling the switching frequency of a two-level bridge arm in the converter to be twice of the switching frequency of a three-level bridge arm by taking two inductive current periods as a switching period for the six-tube Buck-Boost converter, and enabling the switching frequency of the three-level bridge arm to be twice of the switching frequency of the three-level bridge arm; a switching time sequence for realizing soft switching of a full switching device under a wide input voltage range and a load is designed, and the phase shift angle and the duty ratio of each switch are calculated by taking the pulse minimization of inductive current as a target and taking the soft switching of each switching tube as a constraint. According to the method, zero-voltage switching-on of the full switching device under frequency multiplication of the switching frequency of the six-tube Buck-Boost two-level bridge arm can be realized, and the working efficiency of the converter is improved.

The invention relates to a welding machine control method and system. The welding machine control method comprises the following steps: acquiring current information of each converter module; determining current sharing control parameters based on the current information; and a driving control signal of the welding machine is adjusted according to the current sharing control parameters, and the adjusted driving control signal is output. The driving control signals are adjusted according to the current sharing control parameters, independent regulation and control of the converter modules (for example, independent regulation and control of the output currents of the converter modules) are achieved, balanced current distribution among the converter modules is achieved, the problem of current imbalance in a parallel topology structure of the welding machine is effectively solved, and the service life of the welding machine is prolonged. And meanwhile, rapid and stable current-sharing control on each converter module in the welding machine under a high-frequency switching condition is ensured, so that the conduction loss and the switching loss of the welding machine are reduced, the transient current peak is reduced, the service life of the welding machine is prolonged, and the safety and the reliability of welding equipment are improved.

The invention discloses a photovoltaic grid-connected inverter and a modulation method and device thereof, a medium, equipment and a product, the inverter comprises a direct current source, an inverter network, a filter inductor and a power grid, and the inverter network comprises a flying capacitor, a first power switch tube, a second power switch tube, a third power switch tube, a fourth power switch tube and a fifth power switch tube; the positive electrode of the DC source is connected with the collectors of the first power switch tube and the third power switch tube, and the negative electrode is connected with the emitter of the second power switch tube, the collector of the fifth power switch tube and the power grid. The positive electrode of the flying capacitor is connected with the emitter of the first power switch tube and the collector of the second power switch tube, and the negative electrode is connected with the emitter of the third power switch tube, the collector of the fourth power switch tube and the filter inductor. Through insertion of a fifth power switch tube and a flying capacitor, when the photovoltaic grid-connected inverter is in a follow current mode, a direct current source and an alternating current power grid are decoupled, and common-mode voltage is kept unchanged to suppress leakage current.

The application provides an inverse-conducting insulated gate bipolar transistor and a preparation method thereof, and belongs to the technical field of power semiconductor devices, and comprises: a first groove is a gate groove, a second groove is an emitter groove, and a third groove is an ineffective gate groove; in the lateral direction parallel to the cell surface, the first groove, the second groove and the third groove are sequentially and spacedly arranged, and the first groove and the second groove are connected through a fourth groove, and the fourth groove is a gate groove; in the longitudinal direction, the second groove is located between two adjacent fourth grooves. The beneficial effects are as follows: the gate groove and the ineffective gate groove are connected through the lateral gate groove, the forward conduction voltage drop and the conduction loss of the device are reduced; the current channel is increased, the current distribution is more uniform, the heat loss is reduced, the reliability and the power density of the device are improved; the emitter groove is used for repeatedly arranging the polysilicon gate and the metal gate in the lateral and longitudinal directions, the regularly arranged diodes and Schottky diodes are formed, and the reverse diode current distribution is more uniform.

The application discloses a kind of modular multilevel converter thermal balance control method and system based on dynamic retention factor, for the thermal imbalance problem of flexible direct current transmission modular multilevel converter, propose thermal-electricity collaborative control method based on dynamic retention factor (DRF), break through the limitation of traditional capacitor voltage balancing strategy.Capacitor voltage tolerance boundary (rated value ±5%~10%) is set, combined with real-time temperature feedback to build dynamic weight adjustment mechanism, collect IGBT junction temperature to calculate normalized temperature deviation value, generate dynamic retention coefficient, and then obtain the corrected capacitor voltage, in charging mode, low-temperature module is preferentially put into in ascending order, in discharging mode, high-temperature module is preferentially put into in descending order;Further integrate model predictive control (MPC), based on thermal model rolling solution minimization temperature difference objective function, adjust dynamic adjustment coefficient ΔK.The scheme can effectively solve the problem of small-capacitor module thermal fatigue early decline, provide high reliability technical support for high-voltage high-power new energy grid-connected equipment.

The application discloses a totem pole power factor correction circuit, a control method, a device and equipment, the circuit includes a rectifier module, a reactor, a capacitor module, a control module and a switching module, the input end of the rectifier module is connected with an alternating current power supply, and the output end of the rectifier module is used for being connected with a load; the capacitor module is connected with the output end, and includes a first capacitor and a second capacitor in series connection, and the first connection point of the first capacitor and the second capacitor is connected with the alternating current power supply through the switching module; by setting the control module, the rectifier module and the switching module can be controlled according to load parameters, so that the totem pole power factor correction circuit is switched to a synchronous rectification mode or a non-controlled rectification mode, so that the totem pole power factor correction circuit can reduce loss and save resources under the condition that load parameters change, and the circuit efficiency is ensured. The application can be widely applied in the technical field of control.

The utility model discloses a flyback power supply circuit. The flyback power supply circuit comprises a driving chip; the first end of the linear voltage stabilizing sub-circuit is electrically connected with the input power supply end, the second end of the linear voltage stabilizing sub-circuit is electrically connected with the power input end of the driving chip, the third end of the linear voltage stabilizing sub-circuit is electrically connected with the grounding end, and the linear voltage stabilizing sub-circuit is used for maintaining the potential of the power input end of the driving chip; the driving chip responds to the potential of the power supply input end of the driving chip and outputs a driving signal; the voltage transformation module comprises a primary winding and a secondary winding, the first end of the primary winding is electrically connected with the input power supply end, and the secondary winding is electrically connected with the output power supply end; and the switch module responds to enable level conduction of the driving signal output by the driving signal output end, and communicates the primary winding with the grounding end. According to the flyback power supply circuit provided by the embodiment of the invention, the conduction resistance of the switch module can be maintained in a better interval, so that the conduction loss of the switch module is reduced.

The invention provides a PSR flyback conversion circuit, a constant current control method and a power system.The circuit comprises a primary winding circuit, a secondary winding circuit and an auxiliary winding circuit, and the auxiliary winding circuit is a voltage sensing loop used for PSR; the switch tube control unit of the primary winding circuit is configured as follows: when the voltage of the second end of the power switch tube of the primary winding circuit is greater than or equal to a constant current reference voltage, the circuit enters a constant current output mode; and when the circuit enters the constant current output mode, at least setting an excitation reset time ratio based on a first voltage value sensed by the auxiliary winding circuit, the set excitation reset time ratio being greater than or equal to 0.5. Therefore, when the input voltage is far larger than the output reflection voltage N * Vo, it is guaranteed that the secondary winding circuit can output the correspondingly set constant current, the primary and secondary RMS current of the PSR flyback conversion circuit is reduced by increasing the excitation reset time ratio, and then the conduction loss is reduced, and the efficiency is improved.

The application provides a semiconductor device manufacturing method and a semiconductor device. The method comprises the following steps: providing a semiconductor substrate, a first trench is formed in the semiconductor substrate, a field oxide layer is formed on the side wall and the bottom wall of the first trench, so that a space outside the surface of the field oxide layer in the first trench forms a second trench, and the first conductive material is filled in the second trench. The field oxide layer of the side wall of the first trench is removed to a first set depth to form a third trench. A barrier layer is formed on the bottom wall of the third trench, a gate oxide layer is formed on the side wall of the third trench, at least two separated gates are formed in the space outside the surface of the gate oxide layer in the third trench, the barrier layer is removed, and the gap between the separated gates is filled. Then, the space between the bottom of the separated gate and the upper surface of the field oxide layer forms an air layer. Due to the introduction of the air layer, the gate leakage capacitance and the gate-source capacitance are reduced, the switching loss and the conduction loss are reduced, and the opening rate of the device is improved.

The invention discloses a trench gate SiC MOSFET chip and a manufacturing method thereof.The trench gate SiC MOSFET chip uses a composite trench gate structure, the thicknesses of gate oxide layers at the bottom and the side wall of a trench can be controlled respectively, the gate oxide layer at the bottom of the trench at the position where the electric field intensity is large is thickened, and therefore the long-term reliability of a device in the using process is improved, and the reliability of the device is improved. And a thin gate oxide layer is reserved on the side wall groove part, so that the channel resistance and the conduction loss of the device can be reduced. Therefore, the channel resistance and the conduction loss can be effectively reduced while the high reliability of the device is ensured.

The present invention provides a surface acoustic wave ridge waveguide and an integrated device based on an aluminum nitride film. The surface acoustic wave waveguide of the present invention comprises at least a substrate and a piezoelectric film, wherein the piezoelectric film is arranged on the substrate, the width of the piezoelectric film is not less than the thickness of the piezoelectric film; the piezoelectric film comprises a piezoelectric material; and the piezoelectric film further comprises a ridge structure. The surface acoustic wave waveguide of the present invention presents approximately isotropy within the plane, and when the extension direction of the piezoelectric film is bent at an angle, it can ensure that the conduction mode of the surface acoustic wave does not change substantially, thereby reducing the conduction loss of the surface acoustic wave. The surface acoustic wave waveguide of the present invention is more conducive to obtaining a high-performance integrated acoustic circuit, and is preferably used to prepare basic components of integrated acoustic circuits such as SAW beam splitters and ring resonators.

The application relates to the technical field of ocean exploration measurement, and discloses a Doppler log power supply control method and system based on hierarchical intelligent control, which comprises the following steps: acquiring and adaptively filtering original electrical and environmental signals by using a multi-parameter dynamic detection module; performing integration autoregressive moving average model identification based on load current sampling data by using a load adaptive adjustment module, and outputting predicted load current values; combining the prediction results to generate a feedforward instruction, so as to adjust the target switching frequency, duty cycle and working mode of a direct-current-to-direct-current conversion circuit; and using a stability verification layer to evaluate control loop indexes in real time based on a linear periodic time-varying Nyquist criterion, and sending an instruction change control parameter or a warning threshold at an instability critical point. The application improves the power conversion efficiency and dynamic response lag problem under a variable load environment, and improves the anti-disturbance capability and operation reliability of a Doppler log power supply system.

The present invention relates to the field of semiconductor technology, and in particular to a trench PMOS tube, which comprises: a P-type substrate, a P-type epitaxial layer, a cell region and a terminal region surrounding the cell region; the P-type epitaxial layer is located on the P-type substrate; the cell region and the terminal region are located on the P-type epitaxial layer; the cell trench of the cell region comprises a cell groove, a gate oxide layer and a gate polysilicon; the gate oxide layer is located on the bottom and sidewall of the cell groove, and the gate polysilicon is filled in the space formed by the gate oxide layer, wherein the gate oxide layer is a boron-rich oxide layer, and the boron-rich oxide layer is formed by injecting boron ions into the oxide layer. The PMOS tube has the advantages of low on-resistance, high avalanche withstand EAS capability and low voltage creep, thereby improving reliability.

This application discloses a low-power underwater acoustic communication system for underwater navigation and ranging, relating to the field of underwater communication technology. It includes a digital signal processing platform for preprocessing the digital baseband signal to be transmitted to obtain a single-ended analog signal; a transmitting circuit module, comprising at least: a power amplification unit; the power amplification unit being a single chip integrating a PWM modulation circuit, a drive amplification circuit, and a power amplification circuit, wherein the power amplification unit sequentially performs PWM modulation, drive amplification, and power amplification on the single-ended analog signal to output a target amplified signal; and an underwater acoustic transducer for converting the target amplified signal into an acoustic signal and transmitting it into the water medium. This application can reduce energy loss during signal transmission.

The present invention discloses a high PF brushless DC motor drive system based on a bridgeless buck PFC converter, and relates to the technical field of brushless DC motor drive systems; the brushless DC motor drive system comprises a rear-stage inverter, a brushless DC motor and a front-stage bridgeless buck PFC converter; the topological structure of the front-stage bridgeless buck PFC converter comprises a buck conversion unit, a buck-boost conversion unit and an intermediate bus capacitor C o The buck conversion unit includes a switch tube S1 and a rectifier diode D R1 , diode D1, and inductor L1 are used for power conversion in the negative half cycle of AC input; the buck-boost conversion unit includes switch tube S2, rectifier diode D R2 , diode D2, and inductor L2 are used for power conversion in the positive half cycle of AC input; the front-stage bridgeless buck PFC converter realizes positive and negative bipolar AC input and unipolar DC output through buck conversion unit and buck-boost conversion unit; by controlling the output voltage V o , realizing closed-loop control of brushless DC motor speed.