0–30?V common mode range, 120?dB CMRR, and 10?nV/ \sqrt {\text{Hz}} noise floor current shunt monitor IC with an embedded ΣΔ modulated digital interface

Sensing and controlling current flow is a fundamental requirement for many electronic systems, including power management (DC?CDC converters and LDOs), battery chargers, electric vehicles, solenoid positioning, motor control, and power monitoring. Current shunt monitor (CSM) system enables current measurement across an external sense resistor (R _S ) in series to current flow. Proposed CSM system can sense a system (power supply) current from 1 to 500?mA across a typical board Cu-trace resistance of 1??? with less than 10???V input-referred offset, 150?nV/°C offset drift and 0.1% accuracy. Instead of using a costly zero-TC sense resistor (R _S ) that is used in typical CSM systems; proposed method uses existing Cu board trace for sensing. The sense amplifier uses chopper stabilization in the signal chain of the amplifier to suppress input-referred offset down to less than 10???V. Switching current-mode (SI) FIR filtering is used at the instrumentation amplifier output to filter out the chopping ripple at the harmonics of the chopping frequency. A frequency domain Sigma Delta (????FD) ADC enables a digital interface to processor applications. The CSM is fabricated on a 0.7???m CMOS process with three levels of metal with maximum Vds tolerance of 8?V, and operates across a common mode range of 0?C30?V achieving less than 10?nV/ $ \sqrt {\text{Hz}} $ of flicker noise at 100?Hz. By using a semi-digital SI FIR filter, residual chopper ripple is suppressed by more than 7.5?mV_pp from the base line of 8?mV_pp, which is equivalent to 25?dB suppression.     

Temperature dependent current-voltage and capacitance-voltage characteristics of chromium Schottky contacts formed by electrodeposition technique on n-type Si

The variations in the electrical properties of Cr Schottky contacts formed by electrodeposition technique on n-type Si substrate have been investigated as a function of temperature using current-voltage (I-V) and capacitance-voltage (C-V) measurements in the temperature range of 80-320 K by steps of 20 K. The basic diode parameters such as ideality factor (n) and barrier height (Φ_b) were consequently extracted from the electrical measurements. It has been seen that the ideality factor increased and the barrier height decreased with decreasing temperature, when the I-V characteristics were analyzed on the basis of the thermionic emission (TE) theory. The abnormal temperature dependence of the Φ_b and n and is explained by invoking two sets of Gaussian distribution of barrier heights at 320-200 K, and 180-80 K. The double Gaussian distribution analysis of the temperature-dependent I-V characteristics of the Cr/n-type Si Schottky contacts gave the mean barrier heights of 0.910 and 0.693 eV and standard deviations (σ_s) of 109 mV and 72 mV, respectively. Then, these values of the mean barrier height have been confirmed with the modified ln(I₀/T²) − q²/2k²T² versus 1/T plot which belongs the two temperature regions.     

A Compact and Low-Cost MEMS Loudspeaker for Digital Hearing Aids

A microelectromechanical-systems (MEMS)-based electromagnetically actuated loudspeaker to reduce form factor, cost, and power consumption, and increase energy efficiency in hearing-aid applications is presented. The MEMS loudspeaker has multilayer copper coils, an NiFe soft magnet on a thin polyimide diaphragm, and an NdFeB permanent magnet on the perimeter. The coil impedance is measured at 1.5 Omega, and the resonant frequency of the diaphragm is located far from the audio frequency range. The device is driven by a power-scalable, 0.25-mum complementary metal-oxide semiconductor class-D SigmaDelta amplifier stage. The class-D amplifier is formed by a differential H-bridge driven by a single bit, pulse-density-modulated SigmaDelta bitstream at a 1.2-MHz clock rate. The fabricated MEMS loudspeaker generates more than 0.8-mum displacement, equivalent to 106-dB sound pressure level (SPL), with 0.13-mW power consumption. Driven by the SigmaDelta class-D amplifier, the MEMS loudspeaker achieves measured 65-dB total harmonic distortion (THD) with a measurement uncertainty of less than 10%. Energy-efficient and cost-effective advanced hearing aids would benefit from further miniaturization via MEMS technology. The results from this study appear very promising for developing a compact, mass-producible, low-power loudspeaker with sufficient sound generation for hearing-aid applications.     

DisplayPort在电视中的应用

DisplayPort是视频电子标准协会(Video Electronic Standards Association-VESA)新的接口标准,简化了显示设计及其相关的连接.它还以强大的电气特性支持更高的分辨率.虽然从目前的应用来看,DisplayPort接口主要应用于笔记本和显示器,但其也适用于数字电视等很多嵌入式和内部应用.     

A Self-Calibrated On-Chip Phase-Noise Measurement Circuit With −75 dBc Single-Tone Sensitivity at 100 kHz Offset

An on-chip clock phase-noise measurement circuit is presented. Unlike previously reported monolithic measurement techniques that measure jitter in the time domain, the proposed module measures the phase-noise spectrum. The proposed circuit is fully integrated and does not require a spectrally clean reference clock or any external calibration. The module can be integrated as part of a built-in self-test (BIST) scheme for PLL clock synthesizers. The proposed circuit uses a low-noise voltage-controlled delay-line (VCDL) and mixer-based frequency discriminator to extract the phase-noise fluctuations at baseband. A self-calibration circuit is used to operate the measurement circuit at its highest sensitivity point. The proposed circuit is fabricated using a 0.25 mum digital CMOS process and operates up to a 2 GHz carrier frequency. It achieves a single-tone measurement sensitivity of -75 dBc and an equivalent phase-noise sensitivity of -124 dBc/Hz at 100 kHz offset frequency.     

Impact of Sampling Clock Phase Noise on Σ∆ Frequency Discriminators

SigmaDelta frequency discriminators (SigmaDeltaFDs) convert instantaneous frequency deviations of a carrier signal to digital. They are used for decoding narrowband phase or frequency modulated signals in communication receivers, self calibration of RF frequency synthesizers and in digital phase locked loops. In this paper, the impact of reference (sampling) clock phase noise on a SigmaDeltaFD's spurious-free dynamic range (SFDR) is derived. It is shown that for SigmaDeltaFDs with jittered sampling clock, in addition to FM sidebands, a high baseband tonal content is generated degrading overall SFDR. The reference clock phase noise impact is derived mathematically, and two commonly used SigmaDeltaFDs circuits are designed and implemented to verify the results experimentally. Experimental results are shown to match the theoretical prediction of SFDR within 3 dB.     

Prevalence of juvenile chronic arthritis and familial Mediterranean fever in Turkey: a field study

OBJECTIVE: To investigate the prevalence of juvenile chronic arthritis (JCA), familial Mediterranean fever (FMF), and Beh?et's disease in Turkish children through a field survey. METHODS: The field survey was based on cluster centering with 2 level strata. A total of 46,813 children were screened. For the diagnosis of chronic arthritis and Beh?et's previously suggested criteria were used. We have developed criteria for the diagnosis of probable FMF. Children previously diagnosed to have these diseases were also defined and included. RESULTS: JCA was found in 6.4/10,000. 2.8/10,000 children were previously diagnosed as FMF (minimum phenotype frequency). Together with the probable diagnosis of FMF, the prevalence increased to 9.3/10,000. The findings were also compared with those of our center. None of the 46,813 children had Beh?et's disease. CONCLUSION: The prevalence of chronic arthritis is similar to the other childhood populations reported. However, FMF has a very high prevalence.     

Secondary extradural spinal tumours in children

Secondary extradural spinal tumours are very rare, but they comprise most of the extradural neoplasms seen in infancy and childhood. Thirty-nine patients with this type of secondary tumour were treated in our hospital between 1965 and 1991. The diagnosis was proved by biopsy in every case. Following surgical decompression, all 35 survivors had radiotherapy and/or chemotherapy. Their outcome is reported.     

The role of cytokines in Henoch Schonlein purpura

Serum levels of tumor necrosis factor (TNF) and interleukin(IL-1) were studied in 20 HSP patients, in the acute phase and after remission, by ELISA technique. Skin biopsies obtained during the acute phase both from a lesion and from unaffected skin, as well as during remission, were immunostained for TNF, IL-1, and IL-6. The mean age of the patients was 9.8 (5-13). Mean serum TNF levels during the acute phase and remission were 14.0 +/- 8.9 pg/ml, and 6.8 +/- 2.4 pg/ml, respectively (p < 0.05). Serum TNF levels in patients with renal involvement (18.8 +/- 10.2 pg/ml) were significantly higher than in those without (10.8 +/- 6.5 pg/ml) (p < 0.05). Serum levels of IL-1 in the acute phase and remission were undetectable. All specimens showed leukocytoclastic vasculitis. Immunohistochemical studies revealed TNF, and a less intense IL-1 and IL-6 staining in the nucleated epidermal layer, with a granular, intracellular pattern. Staining was significantly increased in the affected skin during the acute phase. These results suggest that TNF, IL-1, and IL-6 may play a role as a mediator of inflammation in HSP.