Full-scale Range Research Articles

Design of 45nm Switched Inverter Scheme (SIS) ADCs for Low Power and High Speed Applications

The Analog to Digital converters (ADC) play a very important role in today’s world of electronic systems. The requirement of present applications demands high speed, low power dissipation, minimum area, low noise and application specific resolution. Out of the various types of ADCs available the flash ADC is most popular for its highest conversion rate and its wide applications. On the down side the flash ADC dissipates high power due to the presence of resistance ladder. The power dissipation further increases with increase in resolution. In this research two different approaches are presented which eliminates the resistor ladder completely and hence reduce the power demand drastically. The first approach is Switched Inverter Scheme (SIS) ADC; it is realized for 3 bits using 7 comparator circuits of varying size in CMOS 45nm technology with Predictive Technology Model (PTM). The test result obtained indicates an offset error of 0.014 LSB. The full scale error is of -0.112LSB. The gain error is of 0.07 LSB, actual full scale range of 0.49V, worst case DNL & INL each of -0.3V. The power dissipation for the SIS ADC is 207.987 µwatts; Power delay product (PDP) is 415.9 fWs, and the area overhead is 1.89µm 2 . The second approach is Sleep transistor SIS ADC. This approach shows 71% improvement in power dissipation. Whereas PDP is found to be 107.3 fWs and area overhead is 1.94 µm2 for Sleep transistor SIS ADC.

Development of a Flexible 3-D Tactile Sensor System for Anthropomorphic Artificial Hand

In this paper, we report a novel flexible tactile sensor array for an anthropomorphic artificial hand with the capability of measuring both normal and shear force distributions using quantum tunneling composite as a base material. There are four fan-shaped electrodes in a cell that decompose the contact force into normal and shear components. The sensor has been realized in a 2ntn 6 array of unit sensors, and each unit sensor responds to normal and shear stresses in all three axes. By applying separated drops of conductive polymer instead of a full layer, cross-talk between the sensor cells is decreased. Furthermore, the voltage mirror method is used in this circuit to avoid crosstalk effect, which is based on a programmable system-on-chip. The measurement of a single sensor shows that the full-scale range of detectable forces are about 20, 8, and 8 N for the x-, y-, and z-directions, respectively. The sensitivities of a cell measured with a current setup are 0.47, 0.45, and 0.16 mV/mN for the x-, y-, and y-directions, respectively. The sensor showed a high repeatability, low hysteresis, and minimum tactile crosstalk. The proposed flexible three-axial tactile sensor array can be applied in a curved or compliant surface that requires slip detection and flexibility, such as a robotic finger.

High Dynamic Range Imaging Concept-Based Signal Enhancement Method Reduced the Optical Coherence Tomography Measurement Variability

To develop and test a novel signal enhancement method for optical coherence tomography (OCT) images based on the high dynamic range (HDR) imaging concept. Three virtual channels, which represent low, medium, and high signal components, were produced for each OCT signal dataset. The dynamic range of each signal component was normalized to the full gray scale range. Finally, the three components were recombined into one image using various weights. Fourteen eyes of 14 healthy volunteers were scanned multiple times using time-domain (TD)-OCT before and while preventing blinking in order to produce a wide variety of signal strength (SS) images on the same eye scanned on the same day. For each eye, a pair of scans with the highest and lowest SS with successful retinal nerve fiber layer (RNFL) segmentation was selected to test the signal enhancement effect. In addition, spectral-domain (SD)-OCT images with poor signal qualities were also processed. Mean SS of good and poor quality scans were 9.0 ± 1.1 and 4.4 ± 0.9, respectively. TD-OCT RNFL thickness showed significant differences between good and poor quality scans on the same eye (mean difference 11.9 ± 6.0 μm, P < 0.0001, paired t-test), while there was no significant difference after signal enhancement (1.7 ± 6.2 μm, P = 0.33). However, HDR had weaker RNFL compensation effect on images with SS less than or equal to 4, while it maintained good compensation effect on images with SS greater than 4. Successful signal enhancement was also confirmed subjectively on SD-OCT images. The HDR imaging successfully restored OCT signal and image quality and reduced RNFL thickness differences due to variable signal level to the level within the expected measurement variability. This technique can be applied to both TD- and SD-OCT images.

Characterization of a Mechanical Motion Amplifier Applied to a MEMS Accelerometer

In this paper, a mechanical amplification concept for microelectromechanical systems (MEMS) physical sensors is proposed with the aim to improve their sensitivity. The scheme is implemented using a system of micromachined levers (microlevers) as a deflection amplifying mechanism. The effectiveness of the mechanism is demonstrated for a capacitive accelerometer. A proof-of-concept single-axis mechanically amplified accelerometer with an amplification factor of 40 has been designed, simulated, and fabricated, and results from its evaluation are presented in this paper. The sensor's amplified output has a sensitivity of 2.39 V/g using an open-loop capacitive pick-off circuit based on charge amplifiers. Experimental results show that the addition of the mechanical amplifier does not alter the noise floor of the sensor. The measured natural frequency of the first mode of the sensor is at 734 Hz, and the full-scale measurement range is up to 7 g with a maximum nonlinearity of 2%. It is shown, through comparison with a conventional design, that the mechanically amplified accelerometer provides higher deflection without sacrificing bandwidth.

A 20-b $\pm$40-mV Range Read-Out IC With 50-nV Offset and 0.04% Gain Error for Bridge Transducers

This paper presents a 20-b read-out IC with ±40-mV full-scale range that is intended for use with bridge transducers. It consists of a current-feedback instrumentation amplifier (CFIA) followed by a switched-capacitor incremental ΔΣ ADC. The CFIA's offset and 1/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> noise are mitigated by chopping, while its gain accuracy and gain drift are improved by applying dynamic element matching to its input and feedback transconductors. Their mismatch is reduced by a digitally assisted correction loop, which further reduces the CFIA's gain drift. Finally, bulk-biasing and impedance-balancing techniques are used to reduce the common-mode dependency of these transconductors, which would otherwise limit the achievable gain accuracy. The combination of these techniques enables the read-out IC to achieve 140-dB CMRR, a worst-case gain error of 0.04% over a 0-2.5 V common-mode range, a maximum gain drift of 0.7 ppm/°C and an INL of 5 ppm. After applying nested-chopping, the read-out IC achieves 50-nV offset, 6-nV/°C offset drift, a thermal noise floor of 16.2 nV/√Hz and a 0.1-mHz 1/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> noise corner. Implemented in a 0.7-μm CMOS technology, the prototype read-out IC consumes 270 μA from a 5-V supply.

10 ps resolution, 160 ns full scale range and less than 1.5% differential non-linearity time-to-digital converter module for high performance timing measurements

We present a compact high performance time-to-digital converter (TDC) module that provides 10 ps timing resolution, 160 ns dynamic range and a differential non-linearity better than 1.5% LSB(rms). The TDC can be operated either as a general-purpose time-interval measurement device, when receiving external START and STOP pulses, or in photon-timing mode, when employing the on-chip SPAD (single photon avalanche diode) detector for detecting photons and time-tagging them. The instrument precision is 15 ps(rms) (i.e., 36 ps(FWHM)) and in photon timing mode it is still better than 70 ps(FWHM). The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an user-friendly software interface. The module proves to be the best candidate for a wide variety of applications such as: fluorescence lifetime imaging, time-of-flight ranging measurements, time-resolved positron emission tomography, single-molecule spectroscopy, fluorescence correlation spectroscopy, diffuse optical tomography, optical time-domain reflectometry, quantum optics, etc.

Development of a mirror mounted fiber optic inclinometer

A fiber optic inclinometer enables long distance transmission in hazardous environments without signal loss. This paper presents a wide measurement range fiber optic inclinometer for a stable sensing principle and simple sensor structure, which were realized using a single transmissive grating panel, reflective mirror, and optical fibers as transceivers. In comparison with the conventional transmission type fiber optic inclinometer design, the proposed scheme's cable design was simplified by 50%. The variation curve of the gravity-referenced static acceleration, measured using the proposed fiber optic inclinometer, was sinusoidal and it was compared with actual gravitational acceleration. The developed inclinometer featured nonlinear sensitivities of 1.97°/rad (90–75°), 2.19°/rad (75–60°), 2.49°/rad (60–45°), 3.23°/rad (45–30°), 5.84°/rad (30–15°), and 10.42°/rad (15–0°) according to the measurement range. The maximum absolute error, which was analyzed at 5° intervals, was 0.96° in the full scale measurement range (−90° to 90°). In the full scale range, the R-square value was 0.9999 between the measured and actual tilt angles based on linear regression analysis, and it demonstrated good agreement.

SPAD Smart Pixel for Time-of-Flight and Time-Correlated Single-Photon Counting Measurements

We present a smart pixel based on a single-photon avalanche diode (SPAD) for advanced time-of-flight (TOF) and time-correlated single photon counting (TCSPC) applications, fabricated in a cost-effective 0.35- m CMOS technology. The large CMOS detector (30- m active area diameter) shows very low noise (12 counts per second at room temperature at 5-V excess bias) and high efficiency in a wide wavelength range (about 50% at 410 nm and still 5% at 800 nm). The analog front-end electronics promptly senses and quenches the avalanche, thus leading to an almost negligible afterpulsing effect. The in-pixel 10-bit time-to-digital converter (TDC) provides 312-ps resolution and 320-ns full-scale range (FSR), i.e., 10-cm single-shot spatial resolution within 50-m depth range in a TOF system. The in-pixel 10-bit memory and output buffers make this smart pixel the viable building block for advanced single-photon imager arrays for 3-D depth ranging in safety and security applications and for 2-D fluorescence lifetime decays in biomedical imaging.

3D force sensor for biomechanical applications

A force sensor with capacitive readout is designed and realized for the measurement of mechanical power transfer. The ultimate aim is to integrate such sensors in a glove that will determine the complete mechanical interaction between the human hand and its environment. The sensor measures the normal force and two perpendicular moments by dividing the read-out into four quadrants. The fabrication process is based on silicon fusion bonding allowing the realization of extremely small gaps (250nm). This, in combination with mechanical amplification due to the sensor structure, results in a large sensitivity of 16pF/N and a full-scale range of 50N.

An 11b Pipeline ADC With Parallel-Sampling Technique for Converting Multi-Carrier Signals

This paper presents a parallel sampling technique for analog-to-digital converters (ADCs) to convert multi-carrier signals efficiently by exploiting the statistical properties of these signals. With this technique, the input signal power of an ADC can be boosted without getting excessive clipping distortion and the ADC can have a higher resolution over the critical small amplitude region. Hence the overall signal to noise and clipping distortion ratio is improved. This technique allows reducing power dissipation and area in comparison to conventional solutions for converting multi-carrier signals. As an example, an 11b switched-capacitor pipeline ADC with the parallel sampling technique applied to its first stage is implemented in CMOS 65 nm technology. It achieves a full-scale input signal range of 2 V differentially with a 1.2 V supply voltage. Simulations show an improvement of more than 5 dB in signal-to-noise-and-clipping-distortion ratio (SNCDR) and around 8 dB in dynamic range (DR) compared to a conventional 11b ADC for converting multi-carrier signals and achieve a comparable SNCDR and noise power ratio (NPR) as a conventional 12b pipeline for converting multi-carrier signals with less than half the power and area.

CCD Readout Electronics for Subaru Telescope Instruments

ABSTRACTA general-purpose CCD readout electronics has been developed for use with the instruments installed on the Subaru telescope. The readout performance of the electronics itself was precisely evaluated. The readout noise measures ∼12 μV rms around the readout speed in the 1.0 V full-scale signal range, which is equivalent to 2.4 e- of the readout noise in the 200,000 e- full-well capacity with the output sensitivity of a CCD. The readout noise falls to ∼1 μV rms at slower readout speeds, which is equivalent to as well. The linearity is throughout almost the entire signal range within the 0.1% linearity error. The gain drift relative to temperature change of the correlated-double-sampling (CDS) circuit and the remnant signal are also measured. The low power consumption readout circuit is designed for mosaic CCD cameras equipped with multiple outputs. The two optical instruments of the Subaru telescope have been using this CCD readout electronics, which achieves the CCD limited readout performance.

A Low-Power Programmable Neural Spike Detection Channel With Embedded Calibration and Data Compression

This paper reports a programmable 400 μm pitch neural spike recording channel, fabricated in a 130 nm standard CMOS technology, which implements amplification, filtering, digitization, analog spike detection plus feature extraction, and self-calibration functionalities. It can operate in two different output modes: 1) signal tracking, in which the neural signal is sampled and transmitted as raw data; and 2) feature extraction, in which the spikes of the neural signal are detected and encoded by piece-wise linear curves. Additionally, the channel offers a foreground calibration procedure in which the amplification gain and the passband of the embedded filter can be self-adjusted. The amplification stage obtains a noise efficiency factor of 2.16 and an input referred noise of 2.84 μVrms over a nominal bandwidth of 167 Hz-6.9 kHz. The channel includes a reconfigurable 8-bit analog-to-digital converter combined with a 3-bit controlled programmable gain amplifier for adjusting the input signal to the full scale range of the converter. This combined block achieves an overall energy consumption per conversion of 102 fJ at 90 kS/s. The energy consumed by the circuit elements which are strictly related to the digitization process is 14.12 fJ at the same conversion rate. The complete channel consumes 2.8 μW at 1.2 V voltage supply when operated in the signal tracking mode, and 3.1 μW when the feature extraction mode is enabled.

Modeling and validation of a wall-window retrofit system under blast loading

This paper describes the three step model development of a masonry retrofit and window system under external blast loading. First, basic deformation and failure mechanisms are analyzed using finite element methods. SDOF models are then derived separately for the structural response of retrofitted masonry and window systems and validated in full-scale range and shock tube tests. In a third step the model is expanded to two degrees of freedom to predict the coupled behavior. This paper focuses on the engineering models and the derivation of the system parameters. The algorithms are implemented in a PC-based tool for easy and fast application.

An experimental investigation on decoupling performance for a lateral axis micromachined gyroscope with varying environmental parameters

This paper carries out an experiment study of decoupling performance for a novel lateral axis micromachined gyroscope with varying environmental parameters. The non-ideal mathematical model for the coupling mechanism of the gyroscope is established through the gyro dynamic response matrix. The coupling components varying with ambient pressure and temperature induced by stiffness coupling, damping coupling and electrostatic force coupling are semi-analytically discussed. The overall coupling ratio is evaluated via experiments in the custom-built installation. The testing results show that the decoupling performance of the gyroscope is sensitive to the environmental parameters and all the non-ideal errors are determined as a function of ambient pressure and temperature. The coupling error varies from 0.05% to 0.25% within the pressure range of 100 Pa–100 kPa. The characteristics of coupling with temperature are measured from 20°C to 100°C with a variation from 0.35% to 0.41%. The results also indicate that within the range of measured ambient pressure and temperature, the minimum coupling ratio occurs at 100 Pa and room temperature. The overall performance of the gyroscope is tested under the pressure of about 2000 Pa and room temperature to achieve a relatively low coupling ratio. The scale factor is measured to be 7.8 mV (°) 1 s 1 with nonlinearity about 0.45% in the full-scale range of 600 (°) s 1 . The short-term bias stability is approximately 0.06 (°) s 1 (1  ) for 20 min with noise equivalent angular rate evaluated to be 0.077 (°) s 1 Hz 1/2 .

ADC/DAC Loopback Linearity Testing by DAC Output Offsetting and Scaling

Loopback testing is a powerful technique for testing the analog-to-digital converter (ADC) and digital-to-analog converter (DAC) pair embedded in a mixed-signal system-on-chip (SoC). While attractive, its performance is generally limited by the achievable test resolution and the potential fault masking problem. In this work, a loopback linearity testing technique for an ADC/DAC pair is presented; the key idea is to raise the effective ADC and DAC resolution by scaling the DAC output. First, during ADC testing, we scale down the DAC output to achieve the required test stimulus resolution and adjust the DAC output offset to cover the ADC full-scale range. Then, for DAC testing, we raise the effective ADC resolution by scaling up the DAC output. Both simulation and measurement results are presented to validate the proposed technique.

Eddy-Current Sensor Interface for Advanced Industrial Applications

In this paper, a novel integrated eddy-current sensor interface is presented. The main targeted application is displacement measurement in an industrial environment, with resolution in the submicrometer range. A high excitation frequency of about 22 MHz is applied to minimize the skin effect of the generated eddy currents, when thin targets are used. The price to be paid is to process high-frequency signals. This is very challenging when high performance has to be achieved with respect to resolution and stability at minimum power consumption. To ensure high immunity of the interface to electromagnetic interferences, a second-order oscillator with a steep bandpass resonator is utilized as a front-end stage. The noise performance of the front-end stage is analyzed. To reduce the effect of this noise source on the resolution, a ratiometric measurement principle is proposed. In order to extract the displacement information, a novel amplitude-demodulation approach, including an offset cancellation technique, is introduced. The proposed circuit has been designed and implemented in a 0.35-μm BiCMOS process. In this design, the full-scale displacement range is 1.5 mm. The noise level allows a dynamic range of 75 dB with a measurement signal bandwidth of 1 kHz and only 9.5-mW power dissipation. A comparison with state-of-the-art eddy-current sensor interfaces shows an improved figure of merit, which confirms the high performance of the proposed interface.

Comparison of an ultrasonic interferometer manometer and a new dynamic flow control system in the pressure range 1–133 Pa

This work is concerned with comparison of two low-pressure calibration systems at the Korea Research Institute of Standards and Science (KRISS). The ultrasonic interferometer manometer (UIM) which is a national primary standard and the dynamic flow control system (FCS) which can be used for the calibration of vacuum gauges by comparison method by generating precise and stable pressure in the range 1–133 Pa. For this comparison, a capacitance diaphragm gauge (CDG) of 133 Pa full-scale range was used as transfer standard in the overlapping range of 1–133 Pa. The behavior of two systems in the pressure range 1.37–11.5 Pa had large variations which gradually reduced above 11.5 Pa. In the range 1.37–11.5 Pa, the difference in calibration factors for the two systems was 0.0114 with relative deviations of 5.177%. However above 11.5 Pa the corresponding values were 0.0056 and 1.197%, respectively. Since in vacuum metrology, UIM is world-wide recognized as a national calibration standard, the results of this comparison will be used to validate the FCS for calibration of low vacuum gauges.

Performance of a Dynamic Dew Point Method for Moisture Isotherms of Clays

Abstract Laboratory tests were conducted to assess the performance of a dynamic equilibrium method for rapidly measuring water vapor sorption isotherms of clays and clayey soils. Emphasis was placed on quantifying temperature stability, measurement reproducibility, establishing a recommended testing protocol, and comparing dynamically generated isotherms with those obtained using a conventional equilibrium method. Adsorption-desorption loops for water activity (aw) or relative humidity ranging from 0.03 to 0.95 and containing as many as 140 discrete measurements were obtained using the dynamic method in 12–24 h. Far less intensive sorption isotherms using the equilibrium method required ∼600 h (25 days). Measurement reproducibility was within 6 % of the full-scale range. Water contents measured using the dynamic method at aw less than 0.60 compared excellently with values measured using the equilibrium system and are within 10 to 15 % of the full-scale range at higher activity. Comparisons between total suction characteristic curves obtained using the dynamic system and the equilibrium system suggest a practical total suction measurement range from about 100 000 to 400 000 kPa for a wide range of clay types.

A single-mask thermal displacement sensor in MEMS

This work presents a MEMS displacement sensor based on the conductive heat transfer of a resistively heated silicon structure towards an actuated stage parallel to the structure. This differential sensor can be easily incorporated into a silicon-on-insulator-based process, and fabricated within the same mask as electrostatic actuators and flexure-based stages. We discuss a lumped capacitance model to optimize the sensor sensitivity as a function of the doping concentration, the operating temperature, the heater length and width. We demonstrate various sensor designs. The typical sensor resolution is 2 nm within a bandwidth of 25 Hz at a full scale range of 110 µm.

Real-time measurement of the three-axis contact force distribution using a flexible capacitive polymer tactile sensor

In this paper, we report real-time measurement results of various contact forces exerted on a new flexible capacitive three-axis tactile sensor array based on polydimethylsiloxane (PDMS). A unit sensor consists of two thick PDMS layers with embedded copper electrodes, a spacer layer, an insulation layer and a bump layer. There are four capacitors in a unit sensor to decompose a contact force into its normal and shear components. They are separated by a wall-type spacer to improve the mechanical response time. Four capacitors are arranged in a square form. The whole sensor is an 8 × 8 array of unit sensors and each unit sensor responds to forces in all three axes. Measurement results show that the full-scale range of detectable force is around 0–20 mN (250 kPa) for all three axes. The estimated sensitivities of a unit sensor with the current setup are 1.3, 1.2 and 1.2%/mN for the x-, y- and z-axes, respectively. A simple mechanical model has been established to calculate each axial force component from the measured capacitance value. Normal and shear force distribution images are captured from the fabricated sensor using a real-time measurement system. The mechanical response time of a unit sensor has been estimated to be less than 160 ms. The flexibility of the sensor has also been demonstrated by operating the sensor on a curved surface of 4 mm radius of curvature.