A 3.3 V, 10 Bits, Clock-Feedthrough Compensated Switched-Current Second Order Sigma-Delta Modulator

This article presents a low-pass sigma-delta modulator for Analogue-to-Digital conversion. The circuit uses a switched-current technique which presents a well known drawback called clock feedthrough. This phenomenon induces an error on the output signal value. In order to cancel the clock feedthrough effect, we use a new method based on a current feedback loop. The circuit is designed in 0.8 μm AMS “Austria Mikro Systems” single poly CMOS process. Measurements of the modulator are performed under A/D converters characterisation system, and show 55 dB dynamic range at 2.048 MHz sampling rate with 8 kHz input frequency bandwidth. These characteristics are suitable for audio applications.     

Luikov’s Analytical Solution with Complex Eigenvalues in Intensive Drying

Luikov’s equations of heat and mass transfer with pressure gradient have significant applications especially in the case of intensive drying in porous media. The established analytical solution of Luikov’s equations including pressure gradient effect in a complete form is presented in this work. The existence of complex roots in the analytical solution describing intensive drying with pressure gradient was overlooked in literature. A Matlab function capable of searching and sorting out the complex eigenvalues is also showcased. Three test cases are analyzed and compared with numerical solutions: one theoretical case to emphasize the importance of complex roots in analytical solution while two cases of drying process in ceramic and barley kernel to ensure practical applicability. Excellent matching between analytical and numerical results is noticed when complex eigenvalues are included.

     

Efficient recursive least squares parameter estimation algorithm for accurate nanoCMOS variable gain amplifier performances

ABSTRACT

With the aggressive scaling of integrated circuit technology, parametric estimation is a critical task for designers who looked for solutions to the challenges of some Nanoscale CMOS parameters. This paper presented the prediction of primary parameters of CMOS transistor for 16 nm to 10 nm process nodes using both of Bisquare Weights (BW) method and a novel recursive least squares (RLS) parameter estimation algorithm. The proposed RLS algorithm consists of the minimisation of a quadratic criterion relating to the prediction error in order to attain the best estimated parameters of the developed mathematical model. The obtained results thanks to the proposed RLS algorithm were better than those reached using the BW method. Comparisons between Predictive Technology Model (PTM) data and parameters estimated with RLS algorithm were made to check the validity and the consistency of the proposed algorithm. These predicted primary parameters were helpful to estimate and to optimise the performances of the Variable Gain Amplifier (VGA) which was a basic circuit element with a key role in the design of new upcoming receivers.     

Correction to: A subthreshold low-power CMOS LC-VCO with high immunity to PVT variations

This paper presents a capacitor-free low dropout (LDO) linear regulator based on a dual loop topology. The regulator utilizes two feedback loops to satisfy the challenges of hearing aid devices, which include fast transient performance and small voltage spikes under rapid load-current changes. The proposed design works without the need of a decoupling capacitor connected at the output and operates with a 0–100 pF capacitive load. The design has been taped out in a \(0.18\,\upmu \hbox {m}\) CMOS process. The proposed regulator has a low component count, area of \(0.012\, \hbox {mm}^2\) and is suitable for system-on-chip integration. It regulates the output voltage at 0.9 V from a 1.0–1.4 V supply. The measured results for a current step load from 250 to 500 \(\upmu \hbox {A}\) with a rise and fall time of \(1.5\,\upmu \hbox {s}\) are an overshoot of 26 mV and undershoot of 26 mV with a settling time of \(3.5\,\upmu \hbox {s}\) when \({C_L}\) between 0 and 100 pF. The proposed LDO regulator consumes a quiescent current of only \(10.5\,\upmu \hbox {A}\). The design is suitable for application with a current step edge time of 1 ns while maintaining \(\Delta V_{out}\) of 64 mV.     

A subthreshold low-power CMOS LC-VCO with high immunity to PVT variations

This paper presents a current driver with a novel high voltage (HV) switch schematic for the use as a protective switch for recording circuits during the stimulation sequence in neural measurement system. The current driver can source and sink currents of amplitudes up to ±8.2 mA with a HV tolerance from 30 V up to 120 V. The proposed HV switch also tolerates the voltage difference up to 120 V between its terminals. Between stimulation sequences the driver provides the effective isolation of the stimulation electrode from ground and HV supply voltage. The inter pulse current is no more than 60 pA. The chip was fabricated with AMS HV 0.35 \(\mu\)m CMOS technology. For test purposes the complete stimulation system including the proposed chip and the external C8051F410 controller was build. For the proposed system the mismatch between the sourced and sinked current does not exceed 20 \(\mu\)A. The possibility to stimulate with frequencies up to 1 kHz is proven by measurement along with the electrode-tissue model.     

Synthesis, Crystal Structure and Characterization of a New Dabcodiium Hexaaquacobalt(II) Bis(Selenate), (C6H14N2)[Co(H2O)6](SeO4)2

Abstract  

The new hybrid material, cobalt selenate templated by 1,4-diazabicyclo[2.2.2]octane (abbreviated dabco), has been synthesised by the slow evaporation method at room temperature. Its crystal structure was investigated using single crystal X-ray diffraction data. It crystallises in the monoclinic system (space group P2₁/c) with the following unit-cell parameters: a = 12.9169(2) ?, b = 11.9101(2) ?, c = 12.4951(2) ?, β = 108.484(1)°, V = 1823.10(5) ?³ and Z = 4. The supramolecular structure of (C₆H₁₄N₂)[Co(H₂O)₆](SeO₄)₂ consists of isolated [Co(H₂O)]²⁺ and (C₆H₁₄N₂)²⁺ cations and (SeO₄)²⁻ anions linked together by three dimensional hydrogen-bond network. The infrared spectroscopy confirmed the presence of these different entities. The thermal behaviour of the precursor, studied by thermodiffractometry and thermogravimetric analyses, indicates that its decomposition proceeds through three stages giving rise to the cobalt oxide.     

A power management system for energy harvesting and wireless sensor networks application based on a novel charge pump circuit

Energy Harvesting circuits are developed as an alternative solution to supply energy to autonomous sensor nodes in Wireless Sensor Networks. In this context, this paper presents a micro-power management system for multi energy sources based on a novel design of charge pump circuit to allow the total autonomy of self-powered sensors. This work proposes a low-voltage and high performance charge pump (CP) suitable for implementation in standard complementary metal oxide semiconductor (CMOS) technologies. The CP design was implemented using Cadence Virtuoso with AMS 0.35μm CMOS technology parameters. Its active area is 0.112 mm². Consistent results were obtained between the measured findings of the chip testing and the simulation results. The circuit can operate with an 800 mV supply and generate a boosted output voltage of 2.835 V with 1 MHz as frequency.