Fast MOSFET Research Articles

Speed-Power Efficient Novel CMOS Unary-to-Ternary Encoder

A new full-custom design of Unary-to-Ternary-Encoder (UTE) using standard Enhancement-Type-Metal–Oxide-Semiconductor-Field-Effect-Transistor reporting low-PDP (Power-Delay-Product) and low-area is presented. The inherent pass characteristic of the E-MOS-transistor is exploited here to develop the proposed Ternary-Encoder. Theoretical aspects along with the operation of proposed 9:2 and 27:3 UTE are discussed. The complete UTE is designed and optimized on 32 nm standard CMOS technology at 0.9 V supply-rail and 27°C. Ternary digits “0”, “1” and “2” are represented with 0 V, 0.45 V and 0.9 V respectively. The proposed design is validated through extensive T-Spice front-end transient simulations with all possible test patterns. The layout of the proposed design is completed on 32 nm Single-Poly-Double-Metal (SPDM) CMOS--Technology. After DRC and LVS post-layout simulation with extracted parasitic and 1 fF load, is carried out. The valuated performance of the 9:2 UTE is next compared with a recent candidate design to this end, from open literature to benchmark. The Power-Delay-Product (PDP) of proposed UTE is measured by applying ±10% supply variation from nominal on slow, typical and fast MOSFET at −40°C, 27°C and 85°C. Finally, the speed-power characteristic of the proposed 9:2 UTE is explored under different load conditions from 1 to 10 fF.

Ultrafast Switching of SiC MOSFETs for High-Voltage Pulsed-Power Circuits

Due to their fast switching capabilities, silicon carbide (SiC) MOSFETs are increasingly used in high-voltage pulsed-power circuits where fast and flexible high-voltage pulses are required (e.g. for plasma-processing applications), such as in our solid-state Impedance-matched Marx generator. The turn-on time of SiC MOSFETs mainly depends on the gate-driving technique and its implementation. Therefore, many studies focus on SiC MOSFET gate-driving methods. In this article, a gate-boosting driving method that was previously proposed for IGBTs is optimized for SiC MOSFETs and applied to a very fast MOSFET to reduce turn-on time as much as possible. A prototype of the optimized gate-boosting driver was built and tested to assess its performance. The test results validate the effectiveness of the optimized gate-driving method and showed that a MOSFET turn-on time of below 2 ns is achievable at a high operating voltage and moderate current and below 3 ns for a wider range of load-current and operating-voltage conditions. Furthermore, current rise rates of 38.7 kA/μs at 356-A load current are possible. All these results are considerably faster than ever demonstrated before.

Two Transistors Voltage-Measurement-Based Test Structure for Fast MOSFET Device Mismatch Characterization

This work presents a test structure targeted to measure MOSFET mismatches with a fast method. It relies on two single-spot voltage measurements in order to extract $\Delta V_{TH}$ and $\Delta \beta / \beta $ separately. The new methodology gives a theoretical increase in the measurement speed of 30x (23.17x in practice). The coefficient of determination ( $R^{2}$ ) of the linear regression analysis is used to compare standalone transistor measurements against the new proposed methodology. The correlation in the data demonstrates values not less than 0.94 ( $R^{2}\geq0.94$ ). The test structure can reproduce parameter correlations, and it is capable of extracting MOSFET mismatch design parameters, such as Pelgrom’s $A_{V_{TH}}$ , with an error of 2% and $A_{\beta }$ , with a negligible error. The experimental data presented herein are taken from measurements in prototypes fabricated in a 65nm CMOS bulk process. The whole circuit is composed of 16 2D addressable DUT device matrices, each having 256 same-size closely-placed MOSFET devices, totaling 4,096 MOS devices used in single-type (NMOS) transistor array.

A fast MOSFET rf switch for low-field NMR and MRI.

TRansmit Array Spatial Encoding (TRASE) MRI uses trains of rf pulses alternately produced by distinct transmit coils. Commonly used coil switching involving PIN diodes is too slow for low- and ultra-low-field MRI and would introduce wait times between pulses typically as long as each individual pulse in a few mT. A MOSFET-based rf switch is described and characterised. Up to hundreds of kHz, it allows for sub-μs switching of rf currents from a single amplifier to several coils with sufficient isolation ratio and negligible delay between pulses. Additionally, current switching at null current and maximum voltage can be used to abruptly stop or start pulses in series-tuned rf coils, therefore avoiding the rise and fall times associated with the Q-factors. RF energy can be efficiently stored in tuning capacitors for times as long as several seconds. Besides TRASE MRI, this energy storage approach may find applications in fast repeated spin-echo experiments. Here, a threefold acceleration of TRASE phase-encoding is demonstrated when MOSFET switches are used instead of fast reed relays.

A Microcontroller-Based Modular Pulsed H.V. Power Supply: Design, Implementation, and Tests on DBD-Based Plasmas

This paper is devoted to the design, implementation, and test of a low cost, modular, and reliable pulsed high-voltage (HV) converter (dc chopper). The distinct characteristics of the present prototype refer to: adjustable voltage amplitude up to 7 kV, amplitude drop less than 4‰ for $2 \times 10$ A output peak current at 5 kHz, adjustable pulse frequency up to 5 kHz, adjustable duty cycle between 1% and 10%, rising/falling time around 100 ns, and jitter about 10 ns. In principle, 1-kV modules based on a fast MOSFET each are combined in series to form a completely modular push–pull switch configuration. Contrary to sophisticated optical fiber-based insulation techniques, the driving low-voltage stage of the power supply is magnetically coupled to the HV stage. The low-voltage stage defines and schedules the HV pulses by means of a microcontroller. The 7 kV is equally distributed along MOSFETs due to balancing networks of passive components. Zener diodes in parallel with MOSFETs provide sufficient protection against overvoltages. The power supply has been successfully tested on dielectric-barrier discharge-based plasmas which have nowadays continuous technological interest.

Step-Down dc-dc Converter for Low Temperature Plasma

This paper presents a step down converter with a high speed rectifier and filter for Argon plasma torches. Buck circuit with a high frequency pulse width modulation control and very fast MOSFET transistor were used for switching. For Argon (Ar) gas Plasma Torches, and by increasing the pulse width, the average output voltage has modified from 80 V up to 100 V. The frequency of the designed step down converter was steady at 20 KHz.

Sensing Power MOSFET Junction Temperature Using Circuit Output Current Ringing Decay

Junction temperature $(T_{j})$ sensing requirements for fast MOSFET junction temperature control and high-power fast switching power converter protection are not easily met with nonintrusive techniques. This paper presents a noninvasive circuit-model-based sensing method suitable for a high-bandwidth hard-switching converter power MOSFET junction temperature estimation without any additional temperature detector. For the purpose of demonstrating MOSFET junction temperature sensing, a chopper circuit is used. The ringing superimposed with a circuit load current is used for MOSFET junction temperature estimation. A “gate drive- $R_{\rm DS-on}{-}L{-}C$ ” resonant model is implemented, indicating the mechanism of power MOSFET turn-on dynamics. Modeling includes the gate-drive output parasitics, power MOSFET intrinsic parameters, PCB parasitics, and load parasitics. To evaluate the methodology, LTspice simulation and experimental results are studied.

Design Considerations for a Fast Stacked-MOSFET Switch

For fast pulse generators using pulse-forming lines for energy storage, a fast MOSFET is employed as switch. It needs to have the capability of switching on the current within a short rise time. Fast switching of MOSFET requires the gate driver next to MOSFET in order to minimize the inductance. To increase the voltage switching capability of a MOSFET switch, several MOSFETs are switched in series. For such a configuration, a synchronous switching of MOSFETs is crucial. Hence, the gate drive circuitry needs to be designed to have equal propagation delay for each MOSFET. The circuitry for two stages of a stacked MOSFET switch including power supply and trigger circuit is designed, set up, and tested. The paper describes some design considerations and shows the results of some first tests.

Development of high voltage power supply for the KSTAR 170 GHz ECH and CD system

A 3.6MW (66kV/55A) DC power supply system was developed for the 170GHz EC H&CD system in KSTAR. The power supply system consists of a cathode power supply (CPS), an anode power supply (APS) and a body power supply (BPS). The cathode power supply is capable of supplying a maximum voltage of −66kV and a current of 55A to the cathode with respect to the collector using pulse step modulation (PSM). The high voltage switching system for the cathode is made by a fast MOS-FET solid-state switch which can turn off the high voltage to the cathode within 3μs in the occurrence of gyrotron faults. The APS is a voltage divider system consisting of a fixed resistor and zener diode units with the capability of 60kV stand-off voltage. The anode voltage with respect to the cathode is controlled in a range of 0–60kV by turning the MOS-FET switches connected in parallel to each zener diode on and off. For high frequency current modulation of the gyrotron, the parallel discharge switch is introduced between the cathode and anode in order to clamp the charged voltage in the stray capacitance. The BPS is a DC power supply with the capability of 50kV/160mA. The nominal operation parameter of BPS was 23kV and 10mA, respectively, and the voltage output is regulated with a stability of 0.025% of the rated voltage. The series MOS-FET solid-state switch is used for on/off modulation in the body voltage sychronizing with anode voltage. The parallel discharge switch is also introduced between the body and collector for high frequency RF modulation. This paper describes the key features of the high voltage power supply system of the KSTAR 170GHz gyrotron as well as the test results of the power supply.

Analysis of an Ultrafast MOSFET Based Pockels Cell Driver

Analysis of fast MOSFET based High voltage switch for High Voltage Electro-Optic Devices is presented. Single MOSFET connection is considered by using Laplace transformation. Based on executed mathematical transforms, directions of improvement ways for typical engineering solutions are analyzed. Improvement directions including fastest operation, optical losses minimization, optical behaviors improvement, cost reducing, size and weight decreasing are considered. Modern Optical Arrangements of an Electro-Optic Shutter Schematic are compared. Different schematic designs of Q-Switch Drivers for Pockels Cell are presented. Parameters of constructed based on presented analysis Q-Switch Driver are given.

Theoretical analysis and simulation for avoiding antenna oscillations without distributed resistance

The so-called Wu and King antenna pattern is widely used in GPR because of its simple design and construction features. The main disadvantage is its limited efficiency due to transmitter energy losses which occur through lumped resistors. Based on the analysis of the electromagnetic field behaviour across the antenna, it is possible to replace the effect of the resistors by either storing the energy of the electric pulses, or damp them by means of one matched resistor, which will theoretically improve the efficiency of the antenna. In this paper we provide a theoretical analysis using a modified transmission line model together with simulation based on delayed potentials among other electromagnetic software, and measurement results using an impulse transmitter with fast MOSFET switches and a matched resistor that support this idea.

Photovoltaic‐powered piston‐type water pump controlled by a linear motor

AbstractThis paper presents a unique technique to control a photovoltaic (PV)‐powered piston‐type water pump. the method uses a linear motor mounted directly onto the piston rod of the pump. This linear motor method replaces the traditional piston‐type water pump, which employs a DC motor with a bulky gear mechanism to convert the rotational motion of the motor to linear motion for the piston.The electric circuit used to control the linear motor employs a four‐quadrant chopper, which uses four fast MOSFETs and a simple logic circuit for the switching.The experimental results show that the PV‐powered linear motor system can be used as an alternative to the PV‐powered DC motor gear system.

Fast gating of a windowless dual-multichannel-plate-intensified array detector

A technique for rapid gating of the gain of a windowless dual-multichannel-plate-intensified array detector is described. A DC bias applied to the plates allows effective switching of the gain with a relatively low-voltage (500 V) pulse. The pulse is generated by discharging 50 Omega transmission lines through a single fast MOSFET. The pulser characteristics and the dependence of the intensifier sensitivity on the applied voltage are discussed. The apparatus was used to obtain time-resolved extreme ultraviolet spectra with an optical aperture time of about 5 ns.