1,721,121 research outputs found
A 0.756-ppm/°C Time-Domain-Based Curvature-Compensated Bandgap Reference
No full textThis paper proposes a time-domain-based architecture for implementing a bandgap reference: indeed, the proportional-to-absolute-temperature (PTAT) voltage is provided by subtracting the gate-to-source voltages (VGS) generated in two subsequent phases by the same diode-connected NMOS device, operating in subthreshold region and biased at different currents. As the same transistor is employed in both phases for the PTAT voltage generation, mismatch effects are inherently reduced. The proposed bandgap reference combines the PTAT and the complementary-to-absolute-temperature (CTAT) voltages by means of a switched capacitor difference amplifier and, if required, includes a dedicated sampling and filtering circuit. It features 5-bits trimming and implements curvature compensation through the addition of an integrated resistor with appropriate temperature dependence to the CTAT branch. The proposed bandgap reference circuit was designed in a standard 130-nm CMOS process and was extensively simulated in Cadence Virtuoso, achieving a worst-case 0.756-ppm/degrees C temperature coefficient
Analysis of Parasitic Effects in Filamentary-Switching Memristive Memories Using an Approximated Verilog-A Memristor Model
No full text
Advances in PPG Sensors Data Acquisition with Light-to-Digital Converters: A Review
No full textLight-to-digital converters (LDCs) are essential components in photoplethysmography (PPG) readout chains. Over the past decade, PPG sensors have gathered increased interest due to their non-invasiveness and employment in a wide variety of applications. Among these are cardiovascular monitoring, brain mapping, glucose sensing, skin cancer detection, ozone pollutant sensing, and commercial fitness tracking devices. This article offers a review of recent developments in PPG monitoring, with a specific focus on LDCs. The critical challenges, such as light-emitting diode (LED) power consumption, low perfusion index (PI), ambient light interference, and motion artifacts (MAs), are discussed in detail. Different sampling methods (uniform aggressive, compressive, and event-driven) are analyzed to provide an overview of the mitigation techniques of the LED power consumption issue. Moreover, specific circuit solutions to overcome the remaining challenges are explored within the power consumption and signal quality trade space. Recent advances in LDCs employing on-chip photodetectors (PDs) and dc cancellation circuits are discussed as they significantly improve the noise performance of the readout and provide a considerable overall power reduction. The article also evaluates state-of-the-art (SoA) circuit design techniques, providing essential considerations and intuitions. Lastly, it outlines future development trends and insights, charting a course for continued innovation in this rapidly evolving field
A 11.3-ppm/°C, two temperature points trimmed current generator for precise RC oscillators
No full textThis paper presents a current generator with trimmed temperature coefficient (TC) to achieve stability over a large temperature range. The proposed circuit is based on the VT-multiplier combined with a metal resistor for temperature compensation and utilizes digital resistor trimming for TC and output current calibration. The circuit has been designed at the transistor level and extensively simulated in a 180-nm BiCMOS process. Simulation results show less than 1% corner and mismatch variation of the nominal 10- μA output current and a remarkably low 11.3-ppm/°C residual temperature coefficient over the range from -40 to 135 °C
A BJT-Based 0.08-mm2 Oversampling SAR Temperature-to-Digital Converter for Thermal Drift Compensation in MEMS Inertial Sensors
No full textThis article describes a BJT-based oversampling successive-approximation-register (SAR) temperature-to-digital converter (TDC) designed for the compensation of thermal drift in high-precision micro-electro-mechanical system (MEMS) inertial sensors, increasingly employed devices in modern motion sensing applications. The system features a fully current-mode processing architecture and combines the low conversion energy advantage of SAR solutions with the resolution refining capability peculiar to Σ Δ modulators. Fabricated in a 180-nm CMOS technology, the TDC occupies a 0.08-mm2 active area and draws 22μA from a 1.8-V supply, resulting in a 2.5-nJ energy per sample according to the proposed temperature-to-digital conversion process. Furthermore, the sensor exhibits a 1.06% worst case inaccuracy in the -20°C to 80 °C temperature range after a first-order trim and offers a 158-mK resolution
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