Step Recovery Diode Research Articles

Evaluation of DSRD-based pulsers for a Dielectric Wall Accelerator

Silicon (Si) drift step recovery diodes (DSRD) are opening switches that form the basis for nanosecond-scale high voltage (HV) pulsers. These pulsers are crucial to the operation of a dielectric wall accelerator (DWA), a compact particle accelerator design for proton beam radiation therapy. For the DWA to operate properly, the pulser must generate HV pulses with fast rise times and widths on the order of 1 ns at an operating frequency above 1 kHz. Several pulser designs are available that can optimally drive DSRDs. The purpose of this study is to investigate the capabilities of two DSRD-based pulsers in the context of the DWA and the required pulse parameters. The first pulser is based on a magnetic saturation transformer (MST) and a DRSD. The second pulser considered is a multi-module MOSFET-DSRD-based pulser. Additionally, Sentaurus TCAD simulations are used to study the influence of the Si DSRD doping profile on the output pulse shape. The MST-DSRD-based pulser is able to generate higher amplitude pulses than the MOSFET-DSRD-based pulser with a single module (9645 V and 1807 V, respectively). However, the multi-module MOSFET-DSRD-based pulser achieves the maximum pulse amplitude (10.9 kV) compared to MST-DSRD-based pulser (9645 V). The MOSFET-DSRD-based pulser also generates pulses with shorter pulse widths compared to the MST-DSRD-based pulser (minimum of 3 ns vs. minimum of 8.36 ns, respectively). With no compression stage, the MOSFET-DSRD-based pulser (with more than one module) generates pulses with consistently faster rise times (≤3.06 ns) compared to the MST-DSRD-based pulser (≤4.31 ns). With a compression stage, the rise times were comparable between the two pulsers (MOSFET-DSRD: 1.66 ns and MST-DSRD: 1.48 ns). Both pulsers are able to operate at 1 kHz and the MOSFET-DSRD-based pulser up to 10 kHz. Parasitic capacitance and coupling between modules of the MOSFET-DSRD-based pulser affect the pulse through their influence on the forward and reverse pumping duration. Simulations show that the p region of the DSRD should be larger than the n doped region. Simulations including a parasitic capacitance, modelling the electrical connections to the DSRD, reduce the pulse amplitude. Simulations of the pulsers incorporating SiC DSRDs show a reduction in the pulse amplitude and a widening of the pulse width in comparison to the Si DSRDs.

Collaborative Design of Pulsed-Power Generator Based on SiC Drift Step Recovery Diode

Collaborative Design of Pulsed-Power Generator Based on SiC Drift Step Recovery Diode

A solid-state pulse power sub-nanosecond SiC DSRD-based generator with high-voltage and high repetition frequency for pulse discharge water treatment

Water treatment is one of the most important issues for all walks of life around the world. The unique advantages of the solid-state power electronic pulses in water treatment make it attractive and promising in practical applications. The output voltage, rising time, repetition rate, and peak power of output pulses have a significant impact on the effectiveness of water treatment. Especially in pulse electric field treatment and pulse discharge treatment, the pulse with fast rising time achieves the advantage of generating plasma without corona, which can avoid water heating effect and greatly improve the efficiency of the pulse generator. High repetition rate can significantly reduce the peak power requirement of the pulse in water treatment application, making the equipment smaller and improving the power density. Therefore, the study developed a high-voltage high frequency sub-nanosecond pulse power generator (PPG) system for wastewater treatment. It adopts SiC DSRD (Drift Step Recovery Diode) solid-state switches and realize modular design, which can achieve high performance and can be flexible expanded according to the requirements of water treatment capacity. Finally, an expandable high-voltage PPG for water treatment is built. The output parameters of the PPG include output pulse voltage range from 1 to 5.28 kV, rise time <600 ps (20%–90%), repetition up to 1 MHz. The experiment results of PPG application for pulse discharge water treatment is presented. The results indicate that the proposed generator achieves high-efficiency degradation of 4-Chlorophenol (4-CP), which is one of the most common chlorophenol compounds in wastewater. From experiment, the homemade system can degrade 450 mL waste water containing 500 mg/L 4-CP in 35 min, with a degradation rate of 98%. Thereby, the requirement for electric field intensity decreased. Through the further quantitative analysis, the impact of frequency, voltage, and electrode spacing on the degradation effect of 4-CP is confirmed.

Investigation of Prepulse of SiC Drift Step Recovery Diode in Fast Interruption Process

Investigation of Prepulse of SiC Drift Step Recovery Diode in Fast Interruption Process

Harnessing ultrawideband technology for enhanced communication and radar detection

This article explores the field of pulse dynamics in functional materials with an emphasis on their use in ultrawideband technology and its significance in high-frequency situations. For thirty years, a great deal of attention in the scientific and technical literature has focused on the production of high-power Gaussian pulses, which are necessary to improve radar detection capabilities. Most notably, using avalanche transistors in conjunction with Step Recovery Diodes has been shown to be an effective way to build pulse generators that support narrow pulse widths. Also describes the complex transistor-based circuitry used to generate pulses, which is based on the avalanche mode principle and requires careful pulse shaping. The balun device is a key component of this technology since it optimizes signal integrity by converting asymmetrical pulses into balanced ones. Step Recovery Diodes are also essential for fine-tuning pulse edges, which guarantees accurate temporal properties that improve communication efficiency. This article offers insights into the transformational potential of UWB technology by offering a thorough review of the technology, including prospective applications and regulatory implications. UWB technology is ready to completely transform the field, from making old communication paradigms obsolete to bringing in a new era of unheard-of communication capabilities. All things considered, this work advances our understanding of UWB technology and pulse dynamics in a sophisticated way, making it an invaluable tool for engineers, researchers, and legislators.

Residual phase noise measurements of elements of the radio frequency path of radiometric receivers

In this work, the measurement of the residual phase noise of amplifiers and frequency multipliers using frequency doublers and step recovery diodes, were performed utilizing the interferometric method. The results obtained showed the possibility of using the interferometric method in measuring the phase noise of radio frequency paths of radiometric receivers. The measured values of residual phase noise can be used to evaluate the characteristics of the radio frequency paths of receivers.

Low-cost dual-comb spectrometer for CO2 monitoring based on gain-switched semiconductor lasers

Dual-comb spectroscopy (DCS) is an emerging technique that has attracted the attention of the research community due to its fast data acquisition and high-spectral resolution properties. Despite its versatility and mechanical stability, the complexity and cost of high performance DCS are still experimentally challenging. We propose a simple and compact DCS system that significantly reduces system costs by incorporating three low-cost key components: direct digital synthesizers and step recovery diodes in the signal generator to operate the lasers under gain-switching regime, and a software-defined radio as a digitizer. The viability of this configuration is demonstrated by performing DCS measurements of carbon dioxide (CO2), with a standard deviation of residual error of only ∼ 0.01. These results will pave the way to the commercial availability of compact, high-resolution DCS systems.

Генератор пар импульсов противоположной полярности с повышенной мощностью с применением сумматора на нерегулярно-включенных полосковых линиях

A pulse pair generator with a subnanosecond front is considered, in which pulses of opposite polarity are created by separate generators, and then supplied to the bridge combiner of the original design (on suspended striplines). For the first time in devices of this type, an output power of 18 watts was achieved. A distinctive feature of this structure is that a half of the power of the generators is dissipated on the ballast resistor (due to the alternating appearance of pulses at the inputs of the combiner). To partially compensate for this effect, a half-standard (25 ohms) input resistance of the adder is selected. In the current circuit of generators it leads to an increase in power takeoff from them. The generators themselves are made on step recovery diodes (SRD) according to a scheme close to the traditional one, but differ by a diode circuit at the output, which eliminates penetration of parasitic lobes of a pulse of opposite polarity to the output and protects the SRD from the action of the pulse of the neighboring generator. The shaper is used in experiments to study nonlinear scattering.

New concept of two-cascade energy compression systems based on drift step recovery diodes

A new concept of effective high-voltage nanosecond pulse generators based on two compression cascades of drift step recovery diodes (DSRDs) is presented. The main advantage of the proposed approach arises from the decoupling of the operation cycles of DSRD cascades while using a single primary switch. This greatly improves the overall efficiency of the system. The first DSRD cascade operates with low pulse current densities. Its operation cycles can be extended resulting in an increase of the compression factor and pulse energy, whereas the loss level is kept at a minimum. The second DSRD cascade operates with high current densities, but the duration of its cycles can be chosen much shorter which ensures good efficiency too. Furthermore, an extension of the working cycle of the first DSRD cascade makes the requirement for the primary switch milder so that even relatively slow low-voltage switches can be employed.

Ultra‐wideband microwave imaging for breast tumor screening using step recovery diode‐based pulse generator

SummaryThe feasibility of a multistatic imaging system built on step recovery diode (SRD)‐based pulse generator for microwave breast cancer detection is investigated to develop a low‐cost and portable non‐invasive screening device in the future. The system consists of a pulse generator, an antenna array, and a sampling oscilloscope, in which the pulse generator generates monocycle pulse with a frequency bandwidth from 510 MHz to 6.1 GHz. Experiments are performed on a breast phantom made up of a breast model using 3D printing technology and soybean oil as internal filler, without the usage of any coupling medium. Four identical omnidirectional antennas sequentially transmit ultra‐wideband (UWB) signal and collect signals scattered inside the breast phantom, and then, the interior image of the phantom is reconstructed by background subtraction method and delay and sum (DAS) imaging algorithm. The system can successfully detect and distinguish a variety of test scenarios including cancerous breast phantom containing target with different size and different depth made by iron ball and bacon and healthy breast phantom. The smallest detectable target is 3 mm bacon, with signal to clutter ratio (SCR) and signal to mean ratio (SMR) metrics of 1.63 and 7.79 dB, respectively, and positioning error and relative error of 2.2 mm and 1.7%, respectively. It proves that the proposed time‐domain imaging system is promising for scaling up the detection range of early breast cancer.

Impact of temperature on dynamic characteristics of 4H-silicon carbide drift step recovery diodes

Silicon carbide (SiC) has advantages in high-temperature applications due to its high thermal conductivity and intrinsic temperature. However, the temperature also affects its physical properties thus the electrical characteristics of SiC-based devices. In this paper, the impact of temperature on the dynamic characteristics of 4H-SiC drift step recovery diode (DSRD) is studied. Both the pulse experiments and the two-dimensional numerical simulations are conducted at variable input voltage (Vin). The results show that both the peak value (Vpeak) of the output pulse voltage and the rising rate (dV/dt) of the pulse front decrease with the increased temperature. As the temperature rises from 25 °C to 125 °C, the Vpeak decreases from 1224 V to 820 V at Vin = 120 V, with a decrease ratio of 33 %. The dV/dt decreases from 214 V/ns to 92 V/ns at Vin = 100 V, with a decrease ratio of 57 %. The main reason for this phenomenon is that the increase in temperature leads to a significant decrease in carrier mobility. This work is of certain reference significance for the application of 4H-SiC DSRD in high-temperature situations.

Characteristics comparison of SiC and Si drift step recovery diode

In order to evaluate the prospects of drift step recovery diode (DSRD) based on Silicon Carbide (SiC) in pulsed power field, the characteristics of DSRD based on SiC and Silicon (Si) are compared. The simulation model of the circuit based on Sentaurus TCAD is established and a trigger circuit using the saturated transformer is adopted. The simulation results show that under the same conditions, SiC DSRD has advantages in the aspect of rise time and it is less affected by pedestal effect, which is detrimental to the pulse quality and produces energy loss. The advantage of Si DSRD is that the amplitude of the output pulse voltage is high. By testing the voltage and the rise time of the output pulse, the influence of different factors including turns ratio and input voltage are discussed. For single chip of SiC DSRD with 5 kV blocking voltage, the turns ratio of transformer should be 1:5 to ensure that the parasitic inductance of transformer is low and the input voltage should be more than 500 V to guarantee that the magnetic core can be saturated. For Si DSRD stacked in series, the rise time and the width of output pulse is relatively stable and have little correlation with the changes of the input voltage, the forward pumping time and the circuit parameters. The experiment proves that SiC DSRD and Si DSRD have the advantages of the rise time and the output pulse voltage, respectively, which is consistent with the simulation results.

A compact ultra-wideband sub-nanosecond pulse generator with step recovery diodes

This article presents a compact ultra-wideband (UWB) sub-nanosecond monocycle pulse generator. The proposed circuit has a simple structure and low cost, and its core components are step recovery diodes (SRDs). It is composed of a power supply circuit, pulse drive circuit, short pulse-forming circuit, and pulse-shaping circuit. A transistor-based drive circuit is used to generate a drive pulse with sharp fall time. Then, a sub-nanosecond pulse width is realized through the combination of two SRDs in series and parallel. Finally, a monocycle pulse is directly formed by the inductance-based differentiator. This design achieves a full pulse width of 406 ps with a 260 mV peak-to-peak amplitude and a −10 dB bandwidth of 510 MHz to 6.1 GHz at a pulse repetition frequency of 10 MHz square waveform. The symmetry and ringing level are 96.9% and −25.3 dB, respectively, providing good symmetry and low ringing with a circuit size of 55 × 15 mm. In actual experiments, two identical UWB antennas with appropriate bandwidth are used to radiate a monopulse to breast phantoms. The results and uncertainty analyses of the test system show that there are distinguishable differences under diverse tumor phantoms and locations, proving that the proposed pulse generator is attractive for the application of UWB breast cancer detection.

Design of an ultra‐wideband picosecond pulse generator based on step recovery diodes with an improved SPICE model

SummaryThis article proposed an ultra‐wideband ultra‐short picosecond pulse generator based on step recovery diodes (SRDs). The equivalent circuit model of SRD is analyzed, and an improved nonlinear simulation program with integrated circuit emphasis (SPICE) model is presented for appropriate circuit simulation in Advanced Design System (ADS) software. An external direct current (DC) voltage source is added to bias the SRD. In this article, a conventional shunt SRD topology configuration is developed to generate the Gaussian pulse. According to the measured data, the Gaussian pulse duration for the shunt SRD pulse generator is 210 ps, with the full width at half‐maximum (FWHM) of 110 ps, and the ringing level is −7.8 dB. Moreover, to further improve the tail ringing level, an SRD's mixed topology configuration is introduced and fabricated. The experimental results indicate that the two SRD mixed pulse generator has a pulse duration of 220 ps with FWHM of 120 ps, validating the reasonability of the improved SRD nonlinear SPICE model in ADS. Additionally, there is a considerable improvement in the ringing level of −11.4 dB.

Time-expanded φOTDR using low-frequency electronics.

Time expanded phase-sensitive optical time-domain reflectometry (TE-φOTDR) is a recently reported technique for distributed optical fiber sensing based on the interference of two mutually coherent optical frequency combs. This approach enables distributed acoustic sensing with centimeter resolution while keeping the detection bandwidth in the megahertz range. In this paper, we demonstrate that TE-φOTDR can be realized with low-frequency electronics for both signal generation and detection. This achievement is possible thanks to the use of a couple of electro-optic comb generators driven by commercially available step recovery diodes. These components are fed by radio frequencies that are orders of magnitude lower than those involved in the signals so far originated by ultrafast waveform generation. The result is a simple, compact, low-cost and potentially field-deployable sensor that works without resorting to any decoding algorithm. Besides, high-resolution distributed sensing is carried out with no need of coding strategies or enhanced backscatter fibers. To check the capabilities of our system, we perform distributed strain sensing over a range of 20 m. The spatial resolution is 3 cm and the acoustic sampling rate can be increased up to 200 Hz. This performance reveals the prospective of the proposed approach for field applications, including structural health monitoring.

Design of a Low-Cost UWB Time-Domain Radar System for Subcentimeter Image Resolution

The design and development of a hybrid Gaussian pulse radar transceiver, including transmitter and receiver, is presented. The transmitter is realized using a transistor-based square pulse generator, a tunable step recovery diode (SRD) Gaussian pulse-shaping network, and a differentiator. The SRD circuit design is modified using a high-pass filter to have a low ringing and narrow pulsewidth. The output pulse with a broadband amplifier has a power of 500 mW, at a pulse repetition frequency (PRF) of 10 MHz, and tunable pulsewidth ranges from 56 to 300 ps. A 90° coupler is configured to convert the Gaussian pulse into a monopulse. Then, a transmitter antenna is used to radiate the pulse, and a separate receiving antenna is used to receive the reflected pulse. The receiver is comprised of a local Gaussian pulse generator, a radio frequency mixer (RF-mixer) accompanied by a low-pass filter (LPF), a low-frequency amplifier (LFA), and an analog-to-digital converter (ADC). The RF-mixer is used for expanding the receiving pulse from the receiving antenna by a factor of 100000. The LPF and LFA are used to detect the envelope of the output of the RF-mixer and amplify it. The ADC is interposed between the LFA and a processor to digitize the expanded pulse for data processing. The validity and reliability of the digitized expanded pulse compared to those received using a sampling oscilloscope are 93% in agreement, which is remarkable. A version of the system is also developed for a single-antenna operation by utilizing an ultrawideband (UWB) coupler as a semicirculator. Both the systems are compared, and the benefits of each are illustrated. The flexibility and performance of the designs are analyzed. The proposed system demonstrates subcentimeter imaging capabilities.

A High-Performance UWB Gaussian Pulse Generator: Analysis and Design

This article aims to investigate the limitations on the amplitude of the conventional step recovery diode (SRD)-based Gaussian pulse transmitter and techniques to overcome the limits. The operation of the modified design is examined and compared with a conventional configuration. The results show a considerable increase in the pulse amplitude. The high pulse amplitude of the modified configuration represents an increase in the transmitter’s output power and its improved probing range. The Gaussian pulse is converted into the first derivative Gaussian pulse using a 90° broadband coupler as a differentiator and a semi-differentiator delay line circuit with balanced stubs. The output monopulse generated using the balanced stub delay line has more symmetric sidelobes with narrower pulsewidth than the 90° couplers. Experimental results have shown the high performance of the proposed transmitter over the conventional designs in terms of pulse amplitude and symmetry.

A Generator of Powerful Nanosecond Pulses Based on a Module of Drift Step Recovery Diodes and a Module of Shock-Ionized Dynistors

A Generator of Powerful Nanosecond Pulses Based on a Module of Drift Step Recovery Diodes and a Module of Shock-Ionized Dynistors

Influence of DSRD Operation Cycle on the Output Pulse Parameters

Drift step recovery diodes (DSRDs) are semiconductor opening switches designed for the forming of high-voltage nanosecond pulses. DSRD-based circuit includes inductive energy storage and works as a high-efficient compression stage of the tens to hundreds of nanoseconds input pulse down to nanosecond or subnanosecond range output pulse. Despite the well-investigated physical principles, a lot of published DSRD simulations, and practical DSRD-based pulsers, the fundamental research aimed at optimization of DSRD circuit has not been conducted yet. The present letter shows the result of extensive experiments elucidating the maximum voltage rise rate, pulse compression ratio, energy losses, and prepulse amplitude in DSRD circuits. The explicit definitions of DSRD pulse parameters, which are vital for the optimization process, are suggested for the first time. It is demonstrated that optimizations of different parameters contradict each other, and there is no universal optimal solution. The compromise should be found for each application using the recommendations presented in the letter.

Application of Nonlinear Transmission Lines for Picosecond Pulse Sharpening

The amplitude and width of the ultrashort pulses depend on the performance of the generator’s electronic elements. The usage of step recovery diodes (SRDs) with picosecond switching time can lead to a significant increase in device cost. In this letter, nonlinear transmission line (NLTL) was built and tested using commercial-off-the-shelf components to improve the performance of the generator that is based on inexpensive diodes. The method to control output pulse duration by keeping the constant amplitude was proposed. Measurement results show that generated ultrashort pulse can be compressed using NLTLs and the output amplitude of the compressed pulse is 54 V and the duration is 240 ps.