1,720,971 research outputs found
A Compact, Dual Channel Flow-based Differential Pressure Sensor with mPa Resolution and Sub-10 mW Power Consumption
Get PDFIn this work, we propose a single-chip sensor for the detection of two extremely low, independent differential pressures. The operating principle consists in measuring the airflow induced by the pressure through a channel of sub-millimeter cross-section [1]. The airflow is measured by differential thermal flow sensors, implementing a recently proposed drift-free offset compensation approach. Use of a low-noise, low-power readout interface, integrated on the same chip as the sensing structures, allowed the achievement of resolutions of 1.29 mPa, which are one order of magnitude lower than state-of-art devices. This performance has been obtained with power consumptions suitable for battery-powered applications
A Compact CMOS Compatible micro-Pirani Vacuum Sensor with Wide Operating Range and Low Power Consumption
Get PDFA micro-Pirani vacuum sensor with an operating pressure range of more than 5 decades is described. The device is fabricated by applying a low-resolution and potentially low-cost front-side bulk micromachining step to a chip produced with a commercial CMOS technology. Maximization of the thermally coupled surfaces has been obtained by stacking all layers available by default in the CMOS process. This design choice and the integration of a low-noise, low-power readout interface allowed achievement of state-of-art performances with a fabrication approach affordable even to SMEs and small University laboratories
A CMOS compatible micro-Pirani vacuum sensor based on mutual heat transfer with 5-decade operating range and 0.3 Pa detection limit
Get PDFA Pirani vacuum sensor based on mutual heating between a heater and a distinct temperature probe, separated by a 5 Î1⁄4m air gap, is proposed. The sensor is fabricated by applying a simple post-processing procedure to chips designed and fabricated using the BCD6s process (Bipolar-CMOS-DMOS) of STMicroelectronics. The sensor layout has been optimized to exploit the layers of the original process in order to enhance the sensor performance. The sensors exhibit a resolution better than 0.4 Pa from nearly 0.3 Pa to 1 kPa and better than 50 Pa from 1 kPa to 100 kPa. The sensor response at the lower extreme of the pressure interval is marked by an offset voltage, which is three orders of magnitude smaller than the full-scale value. Finite Element Method simulations suggest that the offset is due to pressure-independent heat transfer due to radiation and conduction through the substrate. The simulated equivalent offset drift is 50 MPa/K
Precise Measurement of Gas Volumes by Means of Low-Offset MEMS Flow Sensors with μL/min Resolution
Get PDFExperiments devoted to evaluate the performance of a MEMS thermal flow sensor in measuring gas volumes are described. The sensor is a single-chip platform, including several sensing structures and a low-offset, low-noise readout interface. A recently proposed offset compensation approach is implemented obtaining low temperature drift and excellent long time stability. The sensor is fabricated by applying a simple micromachining procedure to a chip produced using the BCD6s process of STMicroelectronics. Application of a gas conveyor allowed inclusion of the sensing structure into a channel of sub-millimeter cross-section. The results of measurements performed by making controlled air volumes pass through the sensor channel in both directions at rates from 0.1 to 5 mL/min are described
A chopper stabilized, low power capacitance to PWM converter for sensor interfacing
No full textA low-power, low voltage capacitance to pulse duration converter with intrinsic low sensitivity to temperature and parasitic capacitances is presented. The circuit uses a dual clock chopper modulation, which significantly lowers the effects of device mismatch. An effective resolution of 7.2 bits with 3.8 uA supply current and operation down to 0.9 Vdd are demonstrated by means of electrical simulations performed on a prototype designed with the UMC 0.18 um process
Integrated thermal flow sensors with programmable power-sensitivity trade-off
No full textA thermal flow sensor integrated with a programmable electronic interface into the same chip is proposed. The sensing structure is a micro-calorimeter with a double heater configuration fabricated with a simple post-processing technique applied to chip designed with a commercial CMOS process. The electronic interface is based on a low-noise, low-power instrumentation amplifier and a configurable heater current driver. The device characterization in nitrogen confirms the possibility to manage the trade-off between the sensitivity and the power delivered to the device by means of the programmable interface
A compact current-mode instrumentation amplifier for general-purpose sensor interfaces
Get PDFThe proposed amplifier architecture follows a consolidated topology based on second-generation current conveyors (CCIIs), optimized for fully-differential operation. The architecture uses gain-boosting to improve the offset and noise characteristics of a recently proposed design. Wide input and output ranges and high accuracy are obtained by designing the CCIIs according to an original two-stage architecture with local voltage feedback. Embedding of chopper switch matrices into the amplifier enables vector analysis of the input signal, expanding the application field. The main strengths of the proposed amplifier are compactness and versatility. Measurements performed on a prototype designed with a 0.18 μm CMOS process are described
A CMOS compact differential band-gap voltage reference with programmable output
No full textA modified band-gap circuit capable of producing programmable output differential reference voltage is described. Analysis of the effects of the amplifier noise and offset on the reference voltage is performed, obtaining a compact formula of general validity. A prototype, based on a switched capacitor amplifier with continuous time output, has been designed using the UMC 0.18 um CMOS process. The circuit produces three digitally selectable output differential voltages in the range 1.22-2.8 V and is capable of sourcing/sinking currents up to of 1 mA. Electrical simulations show that the temperature stability is 38 ppm/°C while the standard deviation of output voltage spread is nearly 0.4%
A compact programmable differential voltage reference with unbuffered 4 mA output current capability and ±0.4 % untrimmed spread
No full textA compact differential voltage reference cell, which combines an original switched capacitor integrator with a digitally programmable bandgap core, is presented. The two-stage integrator maintains an always-valid output voltage while performing correlated double sampling to effectively reduce the effects of offset and flicker noise. Measurements performed on a prototype designed with the UMC 0.18 um CMOS process showed a ±0.4 % untrimmed output voltage spread, 1 Hz flicker noise corner and output current capability of up to 4 mA with a quiescent current consumption of 50 uA
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