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Soluble guanylate cyclase (sGC) modulation has been scrutinized in several disease states including heart failure (HF). Recently, it was shown that an sGC modulator improved HF-related hospitalization significantly, though, there was no benefit related to mortality. Herein, a comprehensive meta-analysis of randomized controlled trials (RCTs) for sGC modulation in HF patients was provided in agreement with the PRISMA statement. A total of 10 RCTs yielding 12 papers were included. There were 7526 patients with heart failure of each phenotype, 4253 in the sGC modulator group and 3273 in the placebo group. Use of sGC modulators in HF patients yielded no significant difference in the risk of all-cause mortality compared to placebo (RR = 0.97, 95% CI 0.88–1.08, p = 0.62). The use of sGC modulators was associated with a trend toward a considerable but non-significant increase in the incidence of SAEs (RR = 1.10, 95% CI 0.99–1.22, p = 0.07), as well as an increased incidence of hypotension and anemia. There was an overall neutral effect of sGC modulation on NT-proBNP levels, 6MWD and mortality, at a cost of slight increase in hypotension and anemia. Of note, the improvement in EQ-5D-based quality of life was significant. Hence, the benefit seems to be driven by distinctive domains of quality of life. [ABSTRACT FROM AUTHOR]

Existing video object segmentation (VOS) methods based on matching techniques commonly employ a reference set comprising historical segmented frames, referred to as 'memory frames', to facilitate the segmentation process. However, these methods suffer from the following limitations: (i) Inherent segmentation errors in memory frames can propagate and accumulate errors when utilized as templates for subsequent segmentation. (ii) The non-local matching technique employed in top-leading solutions often fails to incorporate positional information, potentially leading to incorrect matching. In this paper, we introduce the Modulated Memory Network (MMN) for VOS. Our MMN enhances matching-based VOS methods in the following ways: (i) Introducing an Importance Modulator, which adjusts memory frames using adaptive weight maps generated based on the segmentation confidence associated with each frame. (ii) Incorporating a Position Modulator that encodes spatial and temporal positional information for both memory frames and the current frame. The proposed modulator improves matching accuracy by embedding positional information. Meanwhile, the Importance Modulator mitigates error propagation and accumulation by incorporating confidence-based modulation. Through extensive experimentation, we demonstrate the effectiveness of our proposed MMN, which also achieves promising performance on VOS benchmarks. [ABSTRACT FROM AUTHOR]

High data rate coverage, security, and energy efficiency will play a key role in the continued performance scaling of next-generation mobile systems. Dense, small mobile cells based on a novel network architecture are part of the answer. Motivated by the recent mounting interest in free-space optical (FSO) technologies, this paper addresses a novel mobile fronthaul network architecture based on FSO, spread spectrum codes, and graphene modulators for the creation of dense small cells. The network uses an energy-efficient graphene modulator to send data bits to be coded with spread codes for achieving higher security before their transmission to remote units via high-speed FSO transmitters. Analytical results show the new fronthaul mobile network can accommodate up to 32 remote antennas under error-free transmissions with forward error correction. Furthermore, the modulator is optimized to provide maximum efficiency in terms of energy consumption per bit. The optimization procedure is carried out by optimizing both the amount of graphene used on the ring resonator and the modulator's design. The optimized graphene modulator is used in the new fronthaul network and requires as low as 4.6 fJ/bit while enabling high-speed performance up to 42.6 GHz and remarkably using one-quarter of graphene only. [ABSTRACT FROM AUTHOR]

In this paper, we propose an optically controlling broadband terahertz modulator of a layer-dependent PtSe2 nanofilm based on a high-resistance silicon substrate. Through optical pump and terahertz probe system, the results show that compared with 6-, 10-, and 20-layer films, a 3-layer PtSe2 nanofilm has better surface photoconductivity in the terahertz band and has a higher plasma frequency ωp of 0.23 THz and a lower scattering time τs of 70 fs by Drude–Smith fitting. By the terahertz time-domain spectroscopy system, the broadband amplitude modulation of a 3-layer PtSe2 film in the range of 0.1–1.6 THz was obtained, and the modulation depth reached 50.9% at a pump density of 2.5 W/cm2. This work proves that PtSe2 nanofilm devices are suitable for terahertz modulators. [ABSTRACT FROM AUTHOR]

Sirtuins (SIRTs) represent a class of nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylases that exert a crucial role in cellular signal transduction and various biological processes. The mammalian sirtuins family encompasses SIRT1 to SIRT7, exhibiting therapeutic potential in counteracting cellular aging, modulating metabolism, responding to oxidative stress, inhibiting tumors, and improving cellular microenvironment. These enzymes are intricately linked to the occurrence and treatment of diverse pathological conditions, including cancer, autoimmune diseases, and cardiovascular disorders. Given the significance of histone modification in gene expression and chromatin structure, maintaining the equilibrium of the sirtuins family is imperative for disease prevention and health restoration. Mounting evidence suggests that modulators of SIRTs play a crucial role in treating various diseases and maintaining physiological balance. This review delves into the molecular structure and regulatory functions of the sirtuins family, reviews the classification and historical evolution of SIRTs modulators, offers a systematic overview of existing SIRTs modulation strategies, and elucidates the regulatory mechanisms of SIRTs modulators (agonists and inhibitors) and their clinical applications. The article concludes by summarizing the challenges encountered in SIRTs modulator research and offering insights into future research directions. [Display omitted] • Sirtuins (SIRTs), as key regulatory factors in cellular processes, are deeply involved in many life processes. • SIRTs modulators have shown great potential in treating various diseases and maintaining physiological balance. • The field of SIRTs and its modulators is developing very rapidly. This paper fills the gap in the research summary of SIRTs modulators in time, and provides valuable insights into the challenges encountered in the research field. [ABSTRACT FROM AUTHOR]

In this paper, a dynamically tunable triple plasmon-induced transparency (PIT) is numerically investigated in a simple monolayer graphene- patterned structure. The structure is composed of five graphene strips and a silicon substrate. Electric field distributions show that the triple PIT effect is originated from the strong destructive interference between three bright modes and one dark mode, coupled mode theory (CMT) is utilized to confirm the finite-difference-time-domain (FDTD) simulation. Results show the maximum figure of merit (FOM) and sensitivity can reach 15.88 and 0.91 THz/RIU. A on-to-off electro-optical modulator is realized by tuning the Fermi levels of the graphene, the modulation degrees of amplitude are 79.3 %, 87.1 %, 70.5 %, 79.2 %, and 84.3 %, corresponding to 2.35 terahertz (THz), 3.12THz, 3.58 THz, 3.91THz, and 4.31 THz, respectively. In addition, the effect of polarized angle on the transmission spectra was studied in detail. A multi-frequency polarization modulator can also be realized with modulation degrees of amplitude (MDA) of 77.6 %, 85.9 %, and 93.7 % at 2.09 THz, 2.82 THz, and 3.59 THz, respectively, and the corresponding polarization extinction ratio (PER) are 6.5 dB, 8.5 dB, and 12.1 dB, respectively. Therefore, the results of the paper are significant to the design of multi-frequency, terahertz sensors, slow light, and modulators. [Display omitted] • Multi frequency electro-optic modulator and polarization modulator can be realized. • Compared with three-layer graphene PIT structure , the present structure is simpler. • The RI sensitivity, modulation degrees of amplitude, extinction ratio are excellent. [ABSTRACT FROM AUTHOR]

Three-phase interior permanent magnet synchronous motor (IPMSM) drive systems have gotten widely used recently in various applications due to their speed regulation characteristics and high power density. Compared with classical field-oriented control (FOC) and flux-weakening control, model predictive control (MPC) technique is more efficient and effective in achieving excellent performance without complicated controller tuning, but with explicit constraints. Yet, the optimum application of the MPC algorithm in a machine control system is still in the exploratory stage. In order to lower the current and torque ripples, this paper retains a modulator, but replaces all the proportional integrate control loops, which are contained in the conventional FOC systems with a single MPC controller. Moreover, we adopt a brand-new linearization approach to tackle the strong coupled nonlinear IPMSM mathematical model, obtaining an improved linear plant model, which is suitable for the motor with constant load torque. When it comes to flux-weakening control, the required d-axis current is calculated, after which it is used as the input of the proposed MPC controller, abandoning the previous natural field weakening method. Finally, for the purpose of lowering the dynamic speed and current overshoot, a further constraint in the change rate of manipulated variables is discussed. The improved control algorithm has been verified in both simulation and experiment. [ABSTRACT FROM AUTHOR]

CMOS RF switches support watt-level RF output power while enabling signal processing with high speed. Typically, RF FET switches offer a tradeoff between a power handling and modulation bandwidth. This paper investigates the cause of compression in a FET switch, and the analysis suggests the optimization of the gate driving impedance for a stacked-FET switch. A design methodology is presented to realize watt-level power handling with high fractional bandwidth (FBW). The measurements demonstrate a BPSK modulator that can handle up to 10 W with wide FBW. The high-power, low-insertion loss, and high-modulation bandwidth demonstrate record performance. [ABSTRACT FROM AUTHOR]

Quantum Dot (QD) Optical Modulators can provide high speed modulation in low cost indirect bandgap materials. Si based optical modulators can be realized with the inclusion of self-assembled Ge QDs to provide low cost, high speed CMOS compatible optical devices. In this paper, we present the optical characterization of a novel Ge-QD Si-SiO2 based waveguide for use in as an optical modulator. Optical performance figures of merit are investigated including insertion loss (IL) measurements, and Wavelength dependent loss (WDL). We present a multimode waveguide fabricated with conventional CMOS processing. The waveguide provides 4.43dB/cm loss and individual discrete absorption regimes corresponding to the unique minibands produced by superlattice properties of the self-assembled Ge QDs in the IR regime. Absorption properties of the Ge QDs are demonstrated and verified against the QD superlattice bandgap model. Analysis and simulation is presented to qualitatively compare the QD bandgap energies with the reported optical properties. The QD functionalized structure demonstrates the fundamental optical principles of a QD waveguide, setting the foundation for a active modulation testing of this QD based optical modulator. [ABSTRACT FROM AUTHOR]

In this paper, a second-order asynchronous delta-sigma modulator is proposed based on the active-RC integrators. The operational transconductance amplifiers used in the integrators are improved by employing a class-AB structure with bulk-driven input drivers and quasi-floating gate method in subthreshold region. These circuitry approaches provide better linearity, signal-to-noise ratio and speed for the integrators and hence an overall improvement in the performance of the modulator. Mathematical analyses of the second-order modulator confirm a higher center frequency compared to a first-order one. The increased center frequency transfers redundancy distortions to higher frequencies, which results in wider input bandwidth and better linearity. The proposed ASDM designed in TSMC 130 nm CMOS Technology with a center frequency of 1.73 kHz at supply voltage of 250 mV with a signal-to-noise-plus-distortion ratio of 67.3 dB and the power consumption of 30 nW. [ABSTRACT FROM AUTHOR]

The majority of techniques that deal with the mitigation of in-phase and quadrature-phase (I/Q) imbalance at the transmitter (pre-compensation) require long training sequences, reducing the throughput of the system. These techniques also require a feedback path, which adds more complexity and cost to the transmitter architecture. Blind estimation techniques are attractive for avoiding the use of long training sequences. In this paper, we propose a blind frequency-independent I/Q imbalance compensation method based on the maximum likelihood (ML) estimation of the imbalance parameters of a transceiver. A closed-form joint probability density function (PDF) for the imbalanced I and Q signals is derived and validated. ML estimation is then used to estimate the imbalance parameters using the derived joint PDF of the output I and Q signals. Various figures of merit have been used to evaluate the efficacy of the proposed approach using extensive computer simulations and measurements. Additionally, the bit error rate curves show the effectiveness of the proposed method in the presence of the wireless channel and Additive White Gaussian Noise. Real-world experimental results show an image rejection of greater than 30 dB as compared to the uncompensated system. This method has also been found to be robust in the presence of practical system impairments, such as time and phase delay mismatches. [ABSTRACT FROM AUTHOR]

A wideband sub-harmonically pumped (SHP) modulator and demodulator fabricated in 0.15-\mum GaAs pseudomorphic high electron-mobility transistor technology are demonstrated in this paper. The chip is appropriate for emerging 60-GHz multi-gigabit communication applications. Digital modulation degradation resulting from in-phase/quadrature mismatch is effectively minimized by the proposed power-locked loop system. By overcoming the bandwidth limitations and quadrature errors in amplitude and phase, the sideband suppression ratio exhibits broadband performance with the feedback mechanism. By using the SHP mixer structure, the dc offset problem is mitigated because of decreased 2\,\times\, local oscillator leakage. In addition, sub-circuit design considerations and feedback stability are described in this paper. The SHP modulator and demodulator demonstrate flat conversion-gain responses of -\14 \pm \2 dB and -\14 \pm \1 dB, respectively, from 51 to 68 GHz. Properties of multi-gigahertz modulation and demodulation bandwidths show the potentials for gigabit applications. The amplitude and phase imbalances are restricted within 0.3 dB and 5^\circ (\pm\2.5^\circ), respectively, regardless of modulation or demodulation. High data-rate digital modulation and demodulation are successfully performed through 16-QAM and 64-QAM schemes within four channels of the IEEE 802.15.3c standard with outstanding error vector magnitude performances. [ABSTRACT FROM PUBLISHER]

Sub-harmonic modulator and demodulator are presented in this paper using 0.13-μm standard CMOS technology for millimeter-wave (MMW) wireless gigabit direct-conversion systems. To overcome the main problem of local oscillator (LO) leakage in direct-conversion systems, the sub-harmonically pumped scheme is selected in this mixer design. An embedded four-way quadrature divider is utilized in the sub-harmonic Gilbert-cell design to generate quadrature-phases LO signals at MMW frequency. For broadband applications, a broadband matching design formula is provided in this paper to extend the operational frequency range from 35 to 65 GHz. To improve the flatness of conversion loss at high frequency, high-impedance compensation lines are incorporated between the transconductance stage and LO switching quad of the Gilbert-cell mixer to compensate the parasitic capacitance. The sub-harmonic modulator and demodulator exhibit 6 ± 1.5 dB and 7.5 ± 1.5 dB measured conversion loss, respectively, from 35 to 65 GHz. For MMW wireless gigabit applications, the gigabit modulation signal test is successfully performed through the direct-conversion system in this paper. To our knowledge, this is the first demonstration of the MMW CMOS sub-harmonic modulator and demodulator that feature broadband and gigabit applications. [ABSTRACT FROM AUTHOR]

Active rectifiers/inverters are becoming used more and more often in regenerative systems and distributed power systems. Typically, the interface between the grid and rectifier is either an inductor or an LCL-filter. The use of an LCL-filter mitigates the switching ripple injected in the grid by a three-phase active rectifier. However, stability problems can arise in the current control loop. In order to overcome them, a damping resistor can be inserted, at the price of a reduction of efficiency. The use of active damping by means of control may seem attractive but it is often limited by the use of more sensors compared to the standard control and also by a complex tuning procedure of the controllers. This paper introduces a new active damping method that does not require the use of more sensors. It consists of adding a filter on the reference voltage for the modulator. The tuning process of this filter is easily done, for a wide range of sampling frequencies, with the use of genetic algorithms. This method is used only for the optimum choice of the parameters in the filter and an on-line implementation is not needed. Thus the resulting active damping solution does not need new sensors or complex calculations. Moreover, in the paper particular attention is devoted to the susceptibility of the system in a high polluting environment. [ABSTRACT FROM AUTHOR]

This paper proposes a high data rate, low-power, low-voltage design of OTA-based M-ary ASK, FSK and QAM modulator and demodulator circuits. Conventional D/A converter of M-ary circuit has been replaced with the operational transconductance amplifier-based n-bits to 2n level converter which operates with input frequencies up to 2.1 GHz. OTA-based oscillator and PLL is being designed for high speed M-ary FSK. Eye diagram analysis has been carried out, conforming a very low signal distortion. Theoretical analysis of bit error rate has been done. The circuit analysis and simulation results confirm the reliability and accuracy of the design. Effective layouts and die photographs of the proposed designs are also presented. [ABSTRACT FROM AUTHOR]

V2Ic is a ripple-based control with an excellent performance for load transients and reference voltage tracking because it exhibits a feedforward of the load current and the error of the output voltage. However, if V2Ic is modulated with constant frequency, constant on-time or constant off-time, its dynamic response is hindered by delays in the response. This paper proposes a technique that synchronizes the clock of the converter to initialize the duty cycle when a worst-case load transient occurs using the current through the output capacitor to detect load transients. It is exemplified on a V2Ic control but it is applicable to most of controllers as it only acts on the modulator. [ABSTRACT FROM AUTHOR]

This paper presents a high-efficiency 60-GHz on–off keying (OOK) transmitter (TX) designed for wireless network-on-chip applications. Aiming at an intra-chip communication distance of 20 mm, the TX consists of a drive amplifier (DA), a high-speed OOK modulator, and a transformer-coupled voltage-controlled oscillator. For high efficiency, a common-source topology with a drain-to-gate neutralization technique is chosen for the DA. A detailed mathematical design methodology is derived for the neutralization technique. The bulk-driven OOK modulator employs a novel dual feedthrough cancellation technique, resulting in a 30-dB on–off ratio. Fabricated in a 65-nm bulk CMOS process, the TX consumes only 19 mW from a 1-V supply, and occupies an active area of \ 0.077 mm^2. A maximum modulation data rate of 16 Gb/s with 0.75-dBm output power is demonstrated through measurements, which translates to a bit-energy efficiency of 1.2 pJ/bit. [ABSTRACT FROM AUTHOR]

In communication networks, the volume of traffic, the number of connected devices and users continues to grow. As a result, the energy consumption generated by the communication infrastructure has become an important parameter that needs to be carefully considered and optimized both when designing the network and when operating it in real-time. In this paper, the methodology of calculation of complex parameters of energy consumption for transport telecommunication networks is proposed. Unlike the known techniques, the proposed methodology takes into account heterogeneity and multilayer networks. It also takes into account the energy consumption parameter during the downtime of the network equipment in the process of processing the service data blocks, which is quite an important task for improving the accuracy of energy consumption at the stage of implementing the energy-saving network. We also developed simulation software to estimate and manage the energy consumption of the optical transport network using the LabVIEW environment. This software tool allows telecommunication network designers to evaluate energy consumption, which allows them to choose the optimal solution for the desired projects. The use of electro-and acousto-optical devices for optical transport networks is analyzed. We recommended using electro-optical devices for optical modulators and acousto-optical devices for optical switches. The gain from using this combination of optical devices and the parameter of rij electro-optical coefficient and M2 acousto-optical quality parameter found in the paper is about 36.1% relative to the complex criterion of energy consumption. [ABSTRACT FROM AUTHOR]

This paper presents the results of research conducted on board a ship at a customer's request. The devices used during the experimentation, the values obtained and the entailing conclusions will be presented. Measurements were taken over a period of one year. [ABSTRACT FROM AUTHOR]

This paper reports the RF packaging design for electrooptic modulators operating in the millimeter-wave domain and discusses the RF and optical performances of the module. An \LiNbO3 phase modulator has been integrated in a compact housing offering a 1.0-mm RF coaxial input connector. A coplanar waveguide on a low dielectric-loss alumina substrate has been designed to transition the RF field from the connector to the modulator. A RF insertion loss in the 1–2.5-dB range has been measured for the module over the 70–110-GHz bandwidth. A half-wave voltage comprised between 8.6 V at dc and 20 V at 110 GHz was calculated based on the observation of the optical modulation sidebands over the entire 110-GHz bandwidth. The optical insertion loss of the module was measured at 2.8 dB. [ABSTRACT FROM AUTHOR]

The design and measured results of a broad-band direct quadrature phase shift keying (QPSK) modulator and demodulator are described in this paper. The circuits are fabricated using 1-μm GaAs HBT technology. To suppress the local oscillator ( LO) leakage, the double-balanced mixer is selected as the core unit in the modulator/demodulator. An embedded four-way quadrature divider which includes a Lange coupler and two Baluns is utilized in the system to generate quadrature-phase LO signals. As results of a back-to-back test, the system can operate at data rates in excess of 2 Gb/s (1 Gb/s per I and Q channels) at 30 GHz. The supplies of the modulator and demodulator are 5.0 V and 4.5 V with size of 1.35 mm×3.5 mm and 1.36 mm×3.4 mm, respectively. [ABSTRACT FROM AUTHOR]

In this paper, low-voltage evolution and high-speed operation mixer design are presented for millimeter-wave (MMW) CMOS in-phase/quadrature (I/Q) modulator and demodulator. The modified Gilbert-cell mixer architecture, which eliminates the three-level transistors stacking in the conventional Gilbert-cell mixer, can operate at a reduced supply voltage while maintaining reasonable performance. In addition, IF transimpedance amplifier buffer and wideband RF design are introduced to increase the operation speed of the mixer for MMW gigabit wireless transmission link applications. Using a 0.13-\mum CMOS process, the I/Q modulator and demodulator formed with the modified Gilbert-cell mixers are demonstrated at the MMW. Under 1.2-V standard supply voltage, the modulator and demodulator exhibit excellent conversion gain (CG) flatness of -\3.5 \pm \1.5 dB and -\3 \pm \1.5 dB from 41 to 69.5 GHz and 31 to 69 GHz, respectively. For 60-GHz wireless personal area network applications, \pi/4 differential quadrature phase-shift keying, 16 quadrature amplitude modulation, and binary phase-shift keying modulation signal tests are successfully performed through the direct-conversion system. The results show that the presented monolithic microwave integrated circuits can operate at low-voltage and low-power while providing good CG and high data rate, even up to multigigabit. [ABSTRACT FROM AUTHOR]

The problems of RF identification are discussed. It is shown that the use of passive transponders is preferable, but weak energy of the system in this case reduces the operation distance and decreases the noise immunity of the system. In this paper, it is proposed to use the homodyne method of selecting the useful signal. This solution allows to increase the energy and the noise immunity of the system (the operation distance is increased). Furthermore, the interrogator can treat several transponders simultaneously. [ABSTRACT FROM AUTHOR]

This paper reports the determination of electrical equivalent circuit of ON/OFF modulator in non-radiative dielectric (NRD) guide configurations at Ka-band. Schottky barrier mixer diode is used to realize this modulator and its characteristics are determined experimentally using vector network analyzer. Full wave FEM simulator HFSS is used to determine an equivalent circuit for the mounted diode and modulator in ON and OFF states. This equivalent circuit is used to qualitatively explain the experimental characteristics of modulator. [ABSTRACT FROM AUTHOR]

RF pulsewidth modulation (PWM) has been proposed as an efficiency improving technique for power amplifiers (PAs) handling varying envelope signals. The core idea is to modulate the varying envelope into a square-wave signal such that the width of each pulse is varied according to the envelope, and any phase in- formation is contained in the timing of the pulses. The square wave signal can give a theoretical efficiency of 100% for the subsequent PA. Such a system differs significantly from a conventional up-conversion and PA and, therefore, a significant design challenge results. The first important step is to generate the PWM signal. This paper demonstrates a functional modulator for Universal Mobile Telecommunications System operating at 2 GHz. The modulator is designed in a GaAs HBT process and uses low-frequency feedback combined with predistortion to obtain a high spectral purity. Measurements show a Universal Mobile Telecommunications System PWM signal with more than 10-dB margin to the modulation mask and an error vector magnitude of less than 1.5% rms (requirement: 17.5%). [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the first implementation of the integrated system-on-package (SOP) 60-GHz gigabit modulator and demodulator on liquid-crystal polymer (LCP). LCP provides an organic low-cost low dielectric-constant platform suitable for millimeter-wave passive design and packaging. Firstly, we demonstrate a 60-GHz planar bandpass ifiter and RF/baseband duplexer as the building blocks of the integrated module. Measurement results show `∼3-dB insertion loss in the bandpass filter, as well as the RF path of the duplexer, and a higher than 30-dB isolation between the baseband and RF outputs. We utilize those building blocks in the design and implemented a hybrid 60-GHz antiparallel diode-pair-based 4 × sub-harmonic mixer suitable for direct up or down conversion. Measurement results indicate a better than 17-dB insertion loss with 1.25-GHz baseband bandwidth for the 4 x mixer. Input 1-dB compression point of -2 dam has been measured. Two sub harmonic mixers are integrated back-to-back to perform the simultaneous binary phase-shift keying modulation and demodulation of the pseudo- random binary sequences. Eye diagrams show a better than 13-dB SNR for a data rate up to 1.5 Gb/s. 40-GHz versions of the 4 × sub harmonic mixer and the back-to-back chain have also been im- plummeted. Hence, we present the first integrated millimeter-wave gigabit SOP modulator and demodulator on LCP. [ABSTRACT FROM AUTHOR]

High-frequency multimegawatt polyphase resonant power conditioning techniques have recently been realized as a result of key component developments, cooperative efforts, research and development funding contracts, and newly applied engineering techniques. The first generation 10-MW pulsed converter-modulators, implemented at Los Alamos National Laboratory, Los Alamos, NM, are now utilized for the Oak Ridge National Laboratory, Oak Ridge, TN, Spallation Neutron Source (SNS) accelerator klystron radio frequency amplifier power systems [1]. Three different styles of polyphase resonant converter-modulators were developed for the SNS application. The various systems operate up to 140-kV, or 11-MW pulses, or up to 1.1 MW average power, all from a direct current input of +/-1.2 kV. The component improvements realized with the SNS effort coupled with new applied engineering techniques have resulted in dramatic changes in overall power conditioning topology. As an example, the 20-kHz high-voltage transformers are less than 1% the size and weight of equivalent 60-Hz versions. With resonant conversion techniques, load protective networks are not required. A shorted load de-tunes the resonance which results in limited power transfer. This provides for power conditioning systems that are inherently self-protective, with automatic fault "ride-through" capabilities. By altering and iterating the Los Alamos design, higher power and continuous wave power conditioning systems can now be realized with improved performance and flexibility. This paper will examine the SNS engineering data, briefly review the underlying theory of polyphase resonant conversion techniques, and apply this knowledge to future system topologies. [ABSTRACT FROM AUTHOR]

This paper presents operational data and parameters of the newest generation of polyphase resonant high voltage converter modulator (HVCM) as developed and delivered to the KAERI 100 MeV "PEFP" accelerator. The KAERI design realizes improvements from the SNS and SLAC designs. The present KAERI system operates two parallel THALES TH2089F 350 MHz klystrons with total power draw of 50 amperes at 105 kV. An additional 3 klystron system operating at 105 kV and 75 A is also being considered for the high energy sections of this accelerator. In these systems, to improve the IGBT switching performance, the HVCMs will be fitted with artificial zero-voltage-switching (ZVS) networks at turn-off. This new method of artificial ZVS should result in a 6 fold reduction of IGBT switching losses. This will improve the HCVM conversion efficiency to better than 95% at full average power, which is 500 kW for the 2 klystron system and 750 kW for the 3 klystron system. The artificial ZVS is accomplished by placing a soft switching capacitor network across the resonant boost transformer primary winding. This low loss snubber circuit reduces the dv/dt across the IGBTs at turn-off. As the transformer input busswork is extremely low inductance (<10 nH), the single network acts like it is across each IGBT collector-emitter terminal of the 4 transistor H-bridge switching network. We will review these topological improvements and the overall system as delivered to the KAERI accelerator with details of the installed operational results. [ABSTRACT FROM AUTHOR]