Showing papers on "Dynamic range published in 2007"

Apparatus and method for ranging and noise reduction of low coherence interferometry LCI and optical coherence tomography OCT signals by parallel detection of spectral bands

Abstract: Apparatus and method for increasing the sensitivity in the detection of optical coherence tomography and low coherence interferometry (“LCI”) signals by detecting a parallel set of spectral bands, each band being a unique combination of optical frequencies. The LCI broad bandwidth source is split into N spectral bands. The N spectral bands are individually detected and processed to provide an increase in the signal-to-noise ratio by a factor of N. Each spectral band is detected by a separate photo detector and amplified. For each spectral band the signal is band pass filtered around the signal band by analog electronics and digitized, or, alternatively, the signal may be digitized and band pass filtered in software. As a consequence, the shot noise contribution to the signal is reduced by a factor equal to the number of spectral bands. The signal remains the same. The reduction of the shot noise increases the dynamic range and sensitivity of the system.

Invited article: The fast readout low noise camera as a versatile x-ray detector for time resolved dispersive extended x-ray absorption fine structure and diffraction studies of dynamic problems in materials science, chemistry, and catalysis

Abstract: Originally conceived and developed at the European Synchrotron Radiation Facility (ESRF) as an "area" detector for rapid x-ray imaging studies, the fast readout low noise (FReLoN) detector of the ESRF [J.-C. Labiche, ESRF Newsletter 25, 41 (1996)] has been demonstrated to be a highly versatile and unique detector. Charge coupled device (CCD) cameras at present available on the public market offer either a high dynamic range or a high readout speed. A compromise between signal dynamic range and readout speed is always sought. The parameters of the commercial cameras can sometimes be tuned, in order to better fulfill the needs of specific experiments, but in general these cameras have a poor duty cycle (i.e., the signal integration time is much smaller than the readout time). In order to address scientific problems such as time resolved experiments at the ESRF, a FReLoN camera has been developed by the Instrument Support Group at ESRF. This camera is a low noise CCD camera that combines high dynamic range, high readout speed, accuracy, and improved duty cycle in a single image. In this paper, we show its application in a quasi-one-dimensional sense to dynamic problems in materials science, catalysis, and chemistry that require data acquisition on a time scale of milliseconds or a few tens of milliseconds. It is demonstrated that in this mode the FReLoN can be applied equally to the investigation of rapid changes in long range order (via diffraction) and local order (via energy dispersive extended x-ray absorption fine structure) and in situations of x-ray hardness and flux beyond the capacity of other detectors.

High performance imaging system for diffuse optical tomography and associated method of use

Abstract: A high performance imaging system for diffuse optical tomography is disclosed. A dense grid utilizing sources, e.g., light emitting diodes ('LEDs'), that achieve high performance at high speed with a high dynamic range and low inter-channel crosstalk are complemented by a system of discrete, isolated receivers, e.g., avalanche photodiodes ('APDs'). The source channels have dedicated reconfigurable encoding control signals, and the detector channels have reconfigurable decoding, allowing maximum flexibility and optimal mixtures of frequency and time encoding and decoding. Each detector channel is analyzed by dedicated, isolated, high-bandwidth receiver circuitry so that no channel gain switching is necessary. The resulting improvements to DOT system performance, e.g., increased dynamic range and decreased crosstalk, enable higher density imaging arrays and provide significantly enhanced DOT image quality. A processor can be utilized to provide sophisticated three dimensional modeling as well as noise reduction.

Microfluidic flow rate detection based on integrated optical fiber cantilever.

Abstract: We demonstrate an integrated microfluidic flow sensor with ultra-wide dynamic range, suitable for high throughput applications such as flow cytometry and particle sorting/counting. A fiber-tip cantilever transduces flow rates to optical signal readout, and we demonstrate a dynamic range from 0 to 1500 µL min−1 for operation in water. Fiber-optic sensor alignment is guided by preformed microfluidic channels, and the dynamic range can be adjusted in a one-step chemical etch. An overall non-linear response is attributed to the far-field angular distribution of single-mode fiber output.

Dual mode camera solution apparatus, system, and method

Abstract: A camera solution includes an image sensor and an image processing and control system. At least two different operating modes are supported, with one of the modes having a higher dynamic range. Control of the dynamic range is provided at the system level. The system supports statically or dynamically selecting an operating mode that determines the dynamic range of a camera. In one implementation, the system supports the use of either a conventional image sensor that does not natively support a high dynamic range or a dual-mode image sensor.

Phase Modulation With Interferometric Detection as an Alternative to Intensity Modulation With Direct Detection for Analog-Photonic Links

Abstract: We analyze the performance of analog-photonic links employing phase modulation with interferometric demodulation and compare it to intensity-modulation direct-detection links. We derive expressions for RF gain, RF noise figure, compression dynamic range, and spurious-free dynamic range for both architectures. We demonstrate theoretically and experimentally that phase-modulated links can outperform intensity-modulated links over substantial frequency ranges.

Phase-Only and Amplitude-Phase Only Synthesis of Dual-Beam Pattern Linear Antenna Arrays Using Floating-Point Genetic Algorithms

Abstract: In this paper, we present a comparison study between phase-only and amplitude-phase synthesis of symmetrical dual-pattern linear antenna arrays using floating-point or real-valued genetic algorithms (GA). Examples include a sum pattern and a sector beam pattern. In the former, phase is only optimized with predetermined Gaussian amplitude distribution of fixed dynamic range ratio (|amax/amin|) and in the latter, both are optimized with less dynamic range ratio than the former and yet share a common amplitude distribution.

A 141-dB Dynamic Range CMOS Gas-Sensor Interface Circuit Without Calibration With 16-Bit Digital Output Word

Abstract: In this paper, we present the design and the characterization of a wide-dynamic-range interface circuit for resistive gas-sensors able to operate without calibration. The circuit is based on resistance-to-frequency conversion, which guarantees low complexity. The state-of-the-art of this measurement method has been improved first by separating the resistance value controlled oscillator circuit (RCO) from the sensing device, thus leading to higher linearity performance, and then by exploiting a novel digital frequency measurement system. Measurement results on a silicon prototype, designed in a 0.35-mum CMOS technology, show that the circuit achieves, without calibration, a precision in resistance measurement of 0.4% over a range of 4 decades and better than 0.8% over 5 decades (dynamic range, DR = 141 dB). Furthermore, after calibration, it reaches a precision of 0.4% for resistance values ranging between 1 kOmega and 1 GOmega, thus leading to a DR of 168 dB. The prototype chip consumes less than 15 mW from a 3.3-V supply.

Continuous-wave terahertz imaging with a hybrid system

Abstract: The authors have developed a hybrid system for coherent raster-scan imaging at 0.6THz. It combines a high-power electronic source (a multiplied Gunn emitter) with a femtosecond Ti:sapphire laser in order to achieve a high dynamic range via electro-optic detection. The single-scan dynamic range of 60db at a lock-in time constant of 10ms is sufficient to permit detection of scattered terahertz radiation in addition to specularly reflected/transmitted light. Active synchronization of the electronic source and the laser is not needed because of the remarkably low jitter between the two radiation sources.

A 160 dB Equivalent Dynamic Range Auto-Scaling Interface for Resistive Gas Sensors Arrays

Abstract: In this paper an integrated wide-dynamic-range interface circuit for resistive gas-sensors arrays is presented. The proposed device consists of a multiscale transresistance continuous time amplifier followed by a 13-bit incremental A/D converter. The circuit selects automatically the scale to use for each measurement and includes two digital-to-analog converters for the calibration of offset and gain of each scale. The proposed interface circuit achieves a measurement accuracy almost always better than 0.1 % over a sensor resistance range of more than 5 decades [100 Omega-20 MOmega], leading to an equivalent dynamic range of about 160 dB. The chip has been realized with a 0.35 mum CMOS technology and occupies an area of 3.1 mm2 consuming 6 mW from a 3.3 V power supply.

Fibre optic displacement sensor for the measurement of amplitude and frequency of vibration

Abstract: This paper reports the principle of operation, design aspects, experimentation and performance of an extrinsic fibre optic displacement sensor for the measurement of amplitude and frequency of vibration. The device consists of fibre optic transmitter, fibre optic probe, mini-shaker, power amplifier, dynamic signal analyser and photodiode detector. The fibre optic probe consists of two well-polished PMMA (polymethyl methacrylate) fibres cemented together along some distance over the length. The sensor is capable of measuring vibration amplitudes ranging from 0.008 to 0.74 mm within a frequency range of 75 to 275 Hz. The sensitivity of the device is found to be 0.893 V/mm over 0.6 to 2.1 mm range and - 0.226 V / mm over 2.9 to 5.9 mm range. The simplicity of the design, high degree of sensitivity, dynamic range and the low cost of the fabrication make it suitable for real field applications. With the emerging fly-by-light concept, the fibre optic probe solves many sensing problems in aircrafts. Moreover, accuracy and reliability are the excellent pay-offs of this fibre optic sensor.

Methods, systems and apparatuses using barrier self-calibration for high dynamic range imagers

Abstract: Methods, systems and apparatuses proving a high dynamic range imager. Multiple photosensor integration periods are used to capture pixel signal information. A transistor gate is used to remove electrons from the photosensor between the two successive integration periods providing a non-linear pixel response characteristic having a knee point. Each pixel is calibrated for the knee point which is used during adjustment of the pixel output signal. Each pixel may also be calibrated with an arbitrary signal response curve for multiple light intensities.

Noise Figure Reduction in Externally Modulated Analog Fiber-Optic Links

Abstract: An octave-bandwidth microwave photonic link with a third-order limited spurious-free dynamic range of 121 dB in a 1-Hz bandwidth has been demonstrated. The link noise figure of 9 dB at a modulation frequency of 2 GHz was achieved by using a bias-shifted Mach-Zehnder modulator with an optical input power of 500 mW. This level of performance was realized without electronic or optical linearization

A Time-to-First-Spike CMOS Image Sensor

Abstract: A time-to-first-spike (TTFS) imager was designed such that each pixel outputs a single digital pulse whose timing encodes pixel illumination. For still image applications, this time representation provides a tremendous increase in dynamic range, similar to that of other existing time-based imagers. However, a major advantage of the TTFS imager is that this wide dynamic range can be achieved even for 30 frames/s video applications. A prototype 32times32 TTFS image sensor was fabricated in AMI 0.5 mum CMOS technology. The prototype chip demonstrates a 104 dB dynamic range (limited by the optical equipment), 42 V/electron conversion gain, 1.25 nA/cm2 dark current, and 3.1 mW power consumption at 30 frames/s.

Theoretical and experimental investigation of the thermal resolution and dynamic range of CCD-based thermoreflectance imaging.

Abstract: We demonstrate thermal imaging using a charge-coupled device (CCD) thermoreflectance lock-in technique that achieves a record temperature resolution of 18 mK, 44 dB below the nominal dynamic range of the camera (from 72 to 116 dB) for 10(5) periods of measurement. We show that the quantization limit of the CCD camera does not set the lower bound on the precision of the technique. We present a theoretical description of the measurement technique, accounting for the effects of noise and nonideal analog-to-digital conversion, resulting in analytic expressions for the probability distribution function of the measured signals, and allowing for explicit calculation of resolution and error bars. The theory is tested against parametrically varied measurements and can be applied to other sampled lock-in measurements. We also experimentally demonstrate sub-quantization-limit imaging on a well-characterized model system, joule heating in a silicon resistor. The accuracy of the resistor thermoreflectance measurement is confirmed by comparing the results with those of a standard 3omega measurement.

High-Dynamic-Range Wireless-Over-Fiber Link Using Feedforward Linearization

Abstract: We demonstrate the implementation of feedforward linearization at 5 GHz, which is the highest operating frequency yet reported, with 500-MHz linearization bandwidth having at least 24-dB distortion suppression. Simultaneous reduction of 26-dB third-order intermodulation distortion and 7-dB laser-noise reduction is achieved at 5.2 GHz, leading to enhanced spurious-free dynamic range of 107 dB (1 Hz) in a directly modulated uncooled semiconductor laser for applications in wireless-over-fiber (WoF) systems. This paper also provides detailed analysis on feedforward, theoretical distortion reduction, criteria for component selection, and the effect of dispersion. The effectiveness of feedforward in a multichannel system is demonstrated at 5.8 GHz for fixed wireless systems, such as WiMAX. These results suggest that the feedforward-linearization arrangement can make practical multichannel and multioperator WoF systems.

Current measurements in a wide dynamic range—applications in electrochemical nanotechnology

Abstract: Current measurements in a wide dynamic range from low picoamperes up to a few milliamperes are usually carried by implementing logarithmic current-to-voltage converter circuits. Conductance studies in nanoscale metal | molecule | metal junctions require measurements with a high dynamic range, good accuracy and reasonable speed simultaneously. In this work we propose two novel circuit solutions which comply with these conditions: one is based on a high-accuracy, fine-tunable logarithmic current-to-voltage converter. Another circuit implements a double-output (or multiple-output) linear current-to-voltage converter, for which the problem of range-switching has been circumvented. Both circuits were applied in constructing a low-current bipotentiostat dedicated to the electrochemical formation of molecular-scale gaps, and a novel scanning tunnelling microscope preamplifier stage for current-distance spectroscopy studies.

A Wide-Dynamic-Range CMOS Image Sensor Based on Multiple Short Exposure-Time Readout With Multiple-Resolution Column-Parallel ADC

Abstract: A wide-dynamic-range CMOS image sensor based on synthesis of one long and multiple short exposure-time signals is proposed. A high-speed, high-resolution column-parallel integration type analog-to-digital converter (ADC) with a nonlinear slope is crucial for this purpose. A prototype wide-dynamic-range CMOS image sensor that captures one long and three short exposure-time signals has been developed using 0.25-mum 1-poly 4-metal CMOS image sensor technology. The dynamic range of the prototype sensor is expanded by a factor of 121.5, compared with the case of a single long exposure time. The maximum DNL of the ADC is 0.3 least significant bits (LSB) for the single-resolution mode and 0.7 LSB for the multiresolution mode

High Dynamic Range Imaging and its Application in Building Research

Abstract: This article describes the theory and application of high dynamic range imaging (HDRI). HDRI is a recent technology allowing the capture of images with a much extended dynamic range whose values represent real-world luminance rather than just arbitrary pixel values. This article lays out the steps necessary to create HDR images, and highlights recent developments in the technology and its applications for building research.

High-dynamic-range video for photometric measurement of illumination

Abstract: We describe the design and implementation of a high dynamic range (HDR) imaging system capable of capturing RGB color images with a dynamic range of 10,000,000 : 1 at 25 frames per second. We use a ...

An Optically Integrated Coherent Frequency-Domain THz Spectrometer with Signal-to-Noise Ratio up to 80 dB

Abstract: A terahertz frequency domain spectrometer is implemented using two ErAs:GaAs photomixers in a highly compact configuration, utilizing all solid-state components and no moving parts. The system utilizes a single package integration of two 783 nm distributed feedback laser diodes with a high-resolution wavelength discriminator. Digital signal processing electronics provide precise frequency control and yield ~200 MHz accuracy of the THz signal frequency. Continuous mode-hop-free frequency sweeping is demonstrated with < 1 GHz resolution from 200 GHz to 1.85 THz. The coherent detection sensitivity is shown to be in good agreement with previous theoretical predictions and yields a signal-to-noise ratio of 80 dB/Hz at 200 GHz and 60 dB/Hz at 1 THz through a path length in air of one foot. These levels are more than 10 dB higher than previously measured. The spectrometer frequency resolution and dynamic range are suitable for applications involving analysis of chemical, biological, and explosive materials in solid-phase and gas-phase at atmospheric pressure; system performance is demonstrated via the transmission spectra of atmospheric water vapor.

Gain, Noise Figure and Bandwidth-Limited Dynamic Range of a Low-Biased External Modulation Link

Abstract: We present a broad-bandwidth (1 -12 GHz) low-biased external modulation fiber-optic link without preamplifiers that has a gain of 6 dB-14 dB and a noise figure of < 7.S dB everywhere in this broad bandwidth, with a record low noise figure of only 3.4 dB at 2 GHz. The third-order distortion-limited spurious-free dynamic range (SFDK) of this link within any suboctavc portion of the 1-12 GHz range of operating frequencies is approximately 120 dBHz2/3 in a 1-Hz instantaneous receiver bandwidth. We describe the high-performance components in this link and discuss the extent to which their performance varies with frequency, and show which of these components' frequency-dependent parameters affect which of the three figures of merit (gain, noise figure, and SFDR).

A Wide Dynamic-Range CMOS Image Sensor Using Self-Reset Technique

Abstract: A wide dynamic-range (DR) pixel-level CMOS image sensor with self-reset technique has been fabricated using a 0.18-mum six-metal CMOS technology and tested to verify simultaneous increase of both DR and peak signal-to-noise ratio (SNR). It provides a continuous peak SNR enhancement over a strong incident light range. Maximum achievable DR is measured over 71.1 dB, and SNR keeps increasing at 7.3 dB/decade beyond conventional CMOS image sensors.

A Technique to Extend the Bandwidth of an RF Power Amplifier Test Bed

Abstract: In this paper, a method for increasing the bandwidth of a test bed for dynamic characterization of power amplifiers (PAs) is described. The technique is readily implemented using commercially available instruments, which makes it suitable for, e.g., production testing. The bandwidth extension technique is combined with coherent averaging of the measurements in order to simultaneously increase the bandwidth and dynamic range of the test bed. The errors in the obtained wideband signal are also estimated. The method is evaluated experimentally on a base station PA for the third-generation wideband code division multiple access system and on a Doherty amplifier. A tenfold increase in bandwidth to a total of 144 MHz and a more than 10-dB increase in dynamic range to 78 dB were obtained in practice. In addition, the obtained wideband signal is used for behavioral amplifier modeling.

Design of Fully Digital Controlled Reconfigurable Array Antennas with Fixed Dynamic Range Ratio

Abstract: In this paper, we propose an optimization method based on Genetic Algorithm (GA) for design of reconfigurable dual-beam linear isotropic antenna arrays with phase only control of digital phase shifters The problem is to find a fixed amplitude distribution using four-bit digital attenuator that will generate two broadsided symmetrical beams in vertical plane: a pencil beam with zero phases and a flat-top beam with discrete phases of a five-bit digital phase shifter, with or without pre-fixing the dynamic range ratio (I max /I min) of excitation amplitude distribution to a value equal to or less than seven

A 750 mV Fully Integrated Direct Conversion Receiver Front-End for GSM in 90-nm CMOS

Abstract: The design of RF integrated circuits, at the low voltage allowed by sub-scaled technologies, is particularly challenging in cellular phone applications where the received signal is surrounded by huge interferers, determining an extremely high dynamic range requirement. In-depth investigations of 1/f noise sources and second-order intermodulation distortion mechanisms in direct downconversion mixers have been carried out in the recent past. This paper proposes a fully integrated receiver front-end, including LNA and quadrature mixer, supplied at 750 mV, able to meet GSM specifications. In particular, the direct downconverter employs a feedback loop to minimize second-order common mode intermodulation distortion, generated by a pseudo-differential transconductor, adopted for minimum voltage drop. For maximum dynamic range, the commutating pair is set with an LC filter. Prototypes, realized in a 90-nm RF CMOS process, show the following performances: 51 dBm IIP2, minimum over 25 samples, 1 dB desensitization point due to 3-MHz blocker at -18 dBm, 3.5 dB noise figure (NF), integrated between 1 kHz-100 kHz, 15 kHz 1/f noise corner. The front-end IIP2 has also been characterized with the mixer feedback loop switched off, resulting in an average reduction of 18 dB.

An IF-to-Baseband $\Sigma \Delta$ Modulator for AM/FM/IBOC Radio Receivers With a 118 dB Dynamic Range

Abstract: A single-bit fifth-order complex continuous-time IF-to-baseband SigmaDelta modulator for AM/FM/IBOC receivers is presented. The input IF is 10.7 MHz and the sampling frequency is 41.7 MHz. The modulator achieves a dynamic range of 118dB in AM mode (3 kHz BW), 98dB in FM mode (200 kHz BW), and 86dB in IBOC mode (500 kHz BW). The modulator's high dynamic range enables the realization of an AM radio receiver without a VGA and without an AM channel-selection filter, thereby reducing system complexity and cost. The elimination of the VGA also improves the sensitivity and the overall noise figure of the receiver. The modulator's spurious free dynamic range is 88 dB in the bandwidth from 25 to 525 kHz. The IM2 distance is 92 dB, and the IM3 distance is 91 dB. The ADC was fabricated in a one-poly five-metal 0.18-mum CMOS process with an active area of 6.0mm2. It consumes 210 mW from a 1.8-V supply

High Q, one-dimensional terahertz photonic waveguides

Abstract: A one-dimensional (1D) photonic metal parallel plate waveguide is presented in the spectral range of 0.5–3THz that has high throughput and stop bands with up to the experimental limit of 40dB of dynamic range. By incorporating a defect into the periodic bottom plate of the waveguide, a transmission resonance is generated in the first stop band with a Q value of 120 and a dynamic range of over 17dB. The 1D geometry allows the utilization of the mode matching technique to analytically calculate the transmission of the photonic waveguide.

A 120-dB Dynamic Range CMOS Image Sensor With Programmable Power Responsivity

Abstract: A high dynamic range CMOS image sensor providing a user-programmable power responsivity curve is presented. Each pixel integrates, besides a 4T active pixel structure, a voltage comparator and an analog memory to implement a time-to-saturation scheme while also providing the standard integrated photo-current signal. The sensor generates two 10-bit analog outputs allowing a typical dynamic range exceeding 120 dB with a temporal noise lower than 0.13% and a fixed pattern noise of 0.4% (1.7%) of the total signal swing (2 V) at low (high) irradiance without any external calibration procedures. A 140 times 140-pixel array has been fabricated in a 0.35-mum, two-poly four-metal (2P4M), 3.3-V standard CMOS technology. The chip measures 3.9 times 4.6 mm2 with a pixel pitch of 15 mum and a fill factor of 20%.

A novel optical method providing for high-sensitivity and high-throughput biomolecular interaction analysis

Abstract: We present a novel method for label-free detection of biomolecular interactions based on the surface plasmon resonance (SPR) phenomenon. The method enables simultaneous and extremely sensitive analysis of a large number of samples arranged in a 2D array format on the sensor surface. To realize the approach, a prototype of the optical sensor was constructed. With this sensor, interaction kinetics are sampled at a 10 Hz rate, and the dynamic range of the system extends from 1.32 to 1.38 refractive index units (RIU). While the fluidics for a highly multiplexed system are not yet developed, we optimized the prototype for simultaneous sensing of up to 110 interaction sites. In this configuration, extremely low root-mean-squared (RMS) noise, 2.6 × 10 − 8 RIU / Hz , is obtained. This low noise level corresponds to sensitivity exceeding that of any commercial SPR instrument—even those with little or no multiplexing capability. Simple software changes allow the user to trade off dynamic range and multiplexing in exchange for additional sensitivity enhancement. This capability is demonstrated in experiments we perform characterizing the interaction of carbonic anhydrase II with a small molecule, carboxybenzenesulfonamide.