A 2-D wind sensor, based on microelectromechanical\ud systems (MEMS) flow sensors, is presented. The device consists of\ud a cylinder with a channel network connecting the internal flow sensors\ud with the lateral surface. The pressure distribution developed\ud by the wind on the cylinder’s surface is thus converted into two air\ud flows from which, due to the special channel configuration, wind\ud speed and direction can be unequivocally determined. Since the\ud MEMS devices are located in the channels, their fragile sensing\ud structures are protected from direct exposure to the wind. Performance\ud estimation based on literature data of pressure distributions\ud indicates that the approach is applicable to a wide wind velocity\ud range. The feasibility of the idea is supported by measurements\ud performed on a prototype

This paper presents a new family of Class-AB operational transconductance amplifier (OTA) circuits based on single-stage topologies with non-linear current amplifiers. The proposed variable-mirror amplifier (VMA) architecture is mainly characterized by generating all Class-AB current in the output transistors only, by exhibiting very low sensitivity to both technology and temperature deviations, and by avoiding the need for any internal frequency-compensation mechanism. Hence, this family of OTAs is well-suited for low-power switched-capacitor circuits and specifically optimized for switched-OpAmp fast onoff operation and multi-decade load-capacitance specifications. Analytical expressions valid in all regions of operation are presented to minimize VMA settling time in discrete-time circuits. Also, a complete OTA design example integrated in 0.18µm 1P6M MiM 1.8V CMOS technology is supplied with detailed simulation and experimental results. Compared to resistor-free state-of-art Class-AB OpAmp and OTA literature, the proposed architecture returns the highest measured figure-of-merit value.

A compact, low power interface for capacitive sensors, is described. The output signal is a pulse width modulated (PWM) signal, where the pulse duration is linearly proportional to the sensor differential capacitance. The original conversion approach consists in stimulating the sensor capacitor with a triangular-like voltage waveform in order to obtain a square-like current waveform, which is subsequently demodulated and integrated over a clock period. The charge obtained in this way is then converted into the output pulse duration by an approach that includes an intrinsic tunable low pass function. The main non idealities are thoroughly investigated in order to provide useful design indications and evaluate the actual potentialities of the proposed circuit. The theoretical predictions are compared with experimental results obtained with a prototype, designed and fabricated using 0.32 mu M CMOS devices from the BCD6s process of STMicroelectroncs. The prototype occupies a total area of 1025 x 515 mm(2) and is marked by a power consuption of 84 mu W. The input capacitance range is 0-256 fF, with a resolution of 0.8 fF and a temperature sensitivity of 300 ppm/degrees C

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A single-chip smart flow sensor based on a thermal principle is presented. The device is fabricated through a commercial complementary metal-oxide- semiconductor (CMOS) process combined with a postprocessing procedure. A configurable electronic interface performing signal reading and nonideality compensation is integrated with the sensing structures on the same chip. The interface implements recently proposed approaches to offset and pressure effect compensation. Detailed experimental results are presented demonstrating correct operation of the proposed microsystem

A compact converter from capacitance to pulse width, suitable for interfacing integrated capacitive sensors is described. The circuit has been designed and fabricated using 0.32 μm/ 3.3 V CMOS devices from the BCD6s process of STMicroelectroncs and occupies an area of 1025 × 515 μm2. Measurements performed on the test chip showed an excellent linearity, a temperature drift of 300 ppm/”C, and power consumption as low as 84 μW for continuous operation

A new offset compensation approach for integrated\ud thermal flow meters is described. The method is based on micromachined\ud differential flow sensing structures with the heater split\ud into two identical and symmetrical sections. The power unbalance\ud between the two heaters is used to compensate the intrinsic sensor\ud offset. The effectiveness of the approach is proven by means of experiments\ud performed on micro flow meters fabricated by postprocessing\ud chips produced with a commercial microelectronic process.\ud The tests were devoted to demonstrate the robustness of the offset\ud compensation with respect to variation of both the gas temperature\ud and type

A compact CMOS instrumentation amplifier,\ud based on a properly modified second order Gm–C low pass\ud filter (LPF), is proposed as a possible readout channel for\ud integrated thermal sensors. Low noise and low offset\ud characteristics are obtained by applying chopper modulation\ud to the input transconductor. The high input thermal\ud noise density, typical of low frequency Gm–C filters, has\ud been significantly reduced by adopting a two-stage topology\ud for the first transconductor. Using this approach, an\ud input noise density adequate for thermal sensor interfacing\ud was obtained with no need of off-chip capacitors. The\ud intrinsic filtering property of the amplifier effectively\ud rejects the modulated offset ripple, allowing direct connection\ud of the amplifier output to a low sampling rate AD\ud converter. An original switching strategy involving swapping\ud of the input and feedback ports is used to improve the\ud gain precision. The effectiveness of the technique is proven\ud by means of analytical arguments and electrical simulations\ud performed on a prototype, designed with the STMicroelectronics\ud BCD6s process