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- SRAM performance sensorPublication . Semião, Jorge; Santos, Luis; Santos, Marcelino B.As technology advances and becomes increasingly smaller in scale, it makes performance and reliability a constant problem. Effects such as process variations (P), power-supply voltage variations (V), temperature variations (T) and aging (A) variations (PVTA - Process, Voltage, Temperature and Aging) are key parameters that affect circuit's performance and reliability. In today's SoC (System-on-Chip), the memory capacity is gaining importance, due to the need to store more and more data in the chips. The Complementary Metal Oxide Semiconductor (CMOS) memories are the most used in the integrated circuits, within the several types of memories. In this paper, a new performance sensor for SRAM memories is proposed. The purpose is to signalize when PVTA variations change performance above a certain threshold limit, jeopardizing memory operation and signal integrity. Sensor's sensibility to PVTA variations can be changed in run-time, which allows the sensor to be tuned during circuit's life time. Another important feature is that it can be applied locally in key locations, to monitor the online operation of the memory, or globally, by monitoring a dummy memory in pre-defined conditions.
- Multiple-output DC–DC converters: applications and solutionsPublication . Litrán, Salvador P.; Durán, Eladio; Semião, Jorge; Díaz-Martín, CristianMultiple-output DC–DC converters are essential in a multitude of applications where different DC output voltages are required. The interest and importance of this type of multiport configuration is also reflected in that many electronics manufacturers currently develop integrated solutions. Traditionally, the different output voltages required are obtained by means of a transformer with several windings, which are in addition to providing electrical isolation. However, the current trend in the development of multiple-output DC–DC converters follows general aspects, such as low losses, high-power density, and high efficiency, as well as the development of new architectures and control strategies. Certainly, simple structures with a reduced number of components and power switches will be one of the new trends, especially to reduce the size. In this sense, the incorporation of devices with a Wide Band Gap (WBG), particularly Gallium Nitride (GaN) and Silicon Carbide (SiC), will establish future trends, advantages, and disadvantages in the development and applications of multiple-output DC–DC converters. In this paper, we present a review of the most important topics related to multiple-output DC–DC converters based on their main topologies and configurations, applications, solutions, and trends. A wide variety of configurations and topologies of multiple-output DC–DC converters are shown (more than 30), isolated and non-isolated, single and multiple switches, and based on soft and hard switching techniques, which are used in many different applications and solutions.
- Single-switch non-isolated resonant DC-DC converter for single-input dual-output applicationsPublication . Díaz-Martín, Cristian; Durán, Eladio; Litrán, Salvador P.; Álvarez, José Luis; Semião, JorgeThis paper describes a new configuration of Cuk and SEPIC (Single-Ended Primary Converter) ZVS-QR (zero-voltage switching quasi-resonant) combination DC-DC converter for bipolar output with a single switch. The proposed topology employs a single ground-referenced power switch, which simplifies the gate drive design with a single L-C resonant network and provides a bipolar output voltage with good regulation, acceptable efficiency and a step-down/up conversion ratio. This configuration provides dual-output voltage by switching the power switch to zero voltage, which is an interesting alternative for many applications where small size, light weight and high power density are very important aspects. In order to verify its performance, a SEPIC–Cuk Combination ZVS-QR prototype with a cost-effective commercial resonant controller was designed and tested. The experimental results show that the proposed combined topology is suitable for Single-Input Dual-Output (SIDO) applications.
- Single-switch bipolar output DC-DC converter for photovoltaic applicationPublication . Litrán, Salvador P.; Durán, Eladio; Semião, Jorge; Barroso, Rafael S.Bipolar DC grids have become an adequate solution for high-power microgrids. This is mainly due to the fact that this configuration has a greater power transmission capacity. In bipolar DC grids, any distributed generation system can be connected through DC-DC converters, which must have a monopolar input and a bipolar output. In this paper, a DC-DC converter based on the combination of single-ended primary-inductor converter (SEPIC) and C´ uk converters is proposed, to connect a photovoltaic (PV) system to a bipolar DC grid. This topology has, as main advantages, a reduced number of components and a high e ciency. Furthermore, it can contribute to regulate/balance voltage in bipolar DC grids. To control the proposed converter, any of the techniques described in the literature and applied to converters of a single input and single output can be used. An experimental prototype of a DC-DC converter with bipolar output based on the combination of SEPIC and C´ uk converters was developed. On the other hand, a perturb and observe method (P and O) has been applied to control the converter and has allowed maximum power point tracking (MPPT). The combined converter was connected in island mode and in parallel with a bipolar DC microgrid. The obtained results have allowed to verify the behavior of the combined converter with the applied strategy.
- An open hardware electronic controller for motorized rotary injection valves used in Flow Injection AnalysisPublication . Mozo, J. D.; Otero, J. I.; Durán, E.; Semião, JorgeThis work presents the design, development and the implementation of a motorized injection valve used in Flow Injection Analysis. The built prototype has been developed based on the open hardware emergent philosophy, software and firmware, thus helping the development of a free and independent science. This policy creates a platform of open projects that feed each other, contributing to scientific and technological development while sharing knowledge. The proposed design project can be modified to implant it in other devices or projects according to the needs of each one. Also, the open project can be a great help as teaching material in Universities, since open hardware projects are fully described and documented.