An RFID-Based Self-Biased 40 nm Low Power LDO Regulator for IoT Applications.

There are emerging applications, like bridge structural health monitoring, continuous patient condition and outdoor aiding of the elderly and the disabled, where Internet of things (IoT) nodes are used with very limited accessibility and no connection to the main supply network. They may also be exposed to harsh environmental conditions. These are applications where power and available area constraints are of great concern. In this paper, we design a 1.1 V low dropout (LDO) linear regulator in 40 nm technology to be embedded in IoT nodes. To address these constraints, we used state-of-the-art, variability-aware resistor-less sub-threshold biased CMOS-only ultra low power consumption configurations having low active area. The proposed LDO is internally compensated with embedded 18 pF Miller and 10 pF load capacitances. It can supply 1 mA maximum load current with 0.8 uA quiescent current. The dropout voltage of the regulator is 200 mV with minimum input voltage of 1.3 V. The efficiency of the regulator is 84%, which is about 99% of the maximum achievable efficiency for a 200 mV dropout voltage. The whole circuit, consisting of the embedded voltage reference and the Miller and load capacitances, takes less than 0.007 mm2 of the die size with 1 µW power consumption.

Simple method to generate calibrated synthetic smoke-like atmospheres at microscopic scale.

Artificial smokes focusing on macroscopic or fluid properties of smoke have been available for a long time. This paper presents a simple method to generate fully customizable smoke-like atmospheres at microscopic scale (i.e. considering their constituent particles as discrete elements) using a different approach. Synthetic, reproducible media can be generated combining monodisperse microspheres with known geometrical and optical properties conveniently parameterized. The method is presented as a proof-of-concept, highlighting the design decisions along with their implications. Practical issues such as aerosol nebulization, particle carrier selection or the features of the medium chamber where the smoke-like atmosphere is to be tested are analyzed. A comparison between methanol and ethanol as carriers for polystyrene microsphere nebulization is also made. The method could be the seed for the obtention of standard reference media for calibration or standardized characterization of not only smoke detectors and exhaust smoke sensors but also other instruments relying on optical properties of dispersive media (dust in PV panels, public lighting, etc.).

Self-controlled multilevel writing architecture for fast training in neuromorphic RRAM applications.

Memristor crossbar arrays naturally accelerate neural networks applications by carrying out parallel multiply-add operations. Due to the abrupt SET operation characterizing most RRAM devices, on-chip training usually requires either from iterative write/read stages, large and variation-sensitive circuitry, or both, to achieve multilevel capabilities. This paper presents a self-controlled architecture to program multilevel devices with a short and fixed operation duration. We rely on an ad hoc scheme to self-control the abrupt SET, choking the writing stimulus as the cell addresses the desired level. To achieve this goal, we make use of the voltage divider concept by placing a variable resistive load in series with the target cell. We validated the proposal against thorough simulations using RRAM cells fitting extremely fast physical devices and a commercial 40 nm CMOS technology, both exhibiting variability. For every case the proposed architecture allowed progressive and almost-linear resistive levels in each [Formula: see text] and [Formula: see text] crossbars structures.

Democratizing science with the aid of parametric design and additive manufacturing: Design and fabrication of a versatile and low-cost optical instrument for scattering measurement.

This paper focuses on the application of rapid prototyping techniques using additive manufacturing in combination with parametric design to create low-cost, yet accurate and reliable instruments. The methodology followed makes it possible to make instruments with a degree of customization until now available only to a narrow audience, helping democratize science. The proposal discusses a holistic design-for-manufacturing approach that comprises advanced modeling techniques, open-source design strategies, and an optimization algorithm using free parametric software for both professional and educational purposes. The design and fabrication of an instrument for scattering measurement is used as a case of study to present the previous concepts.

A self-timed multipurpose delay sensor for Field Programmable Gate Arrays (FPGAs).

This paper presents a novel self-timed multi-purpose sensor especially conceived for Field Programmable Gate Arrays (FPGAs). The aim of the sensor is to measure performance variations during the life-cycle of the device, such as process variability, critical path timing and temperature variations. The proposed topology, through the use of both combinational and sequential FPGA elements, amplifies the time of a signal traversing a delay chain to produce a pulse whose width is the sensor's measurement. The sensor is fully self-timed, avoiding the need for clock distribution networks and eliminating the limitations imposed by the system clock. One single off- or on-chip time-to-digital converter is able to perform digitization of several sensors in a single operation. These features allow for a simplified approach for designers wanting to intertwine a multi-purpose sensor network with their application logic. Employed as a temperature sensor, it has been measured to have an error of  ±0.67 °C, over the range of 20-100 °C, employing 20 logic elements with a 2-point calibration.

A 0.0016 mm² 0.64 nJ leakage-based CMOS temperature sensor.

This paper presents a CMOS temperature sensor based on the thermal dependencies of the leakage currents targeting the 65 nm node. To compensate for the effect of process fluctuations, the proposed sensor realizes the ratio of two measures of the time it takes a capacitor to discharge through a transistor in the subthreshold regime. Furthermore, a novel charging mechanism for the capacitor is proposed to further increase the robustness against fabrication variability. The sensor, including digitization and interfacing, occupies 0.0016 mm² and has an energy consumption of 47.7-633 pJ per sample. The resolution of the sensor is 0.28 °C, and the 3σ inaccuracy over the range 40-110 °C is 1.17 °C.