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The power spectrum of quantum fluctuations of the electromagnetic field produced by an elementary particle is determined. It is found that in a wide range of practically important frequencies the power spectrum of fluctuations exhibits an inverse frequency dependence. The magnitude of fluctuations produced by a conducting sample is shown to have a Gaussian distribution around its mean value, and its dependence on the sample geometry is determined. In particular, it is demonstrated that for geometrically similar samples the power spectrum is inversely proportional to the sample volume. It is also argued that the magnitude of fluctuations induced by an external electric field is proportional to the field strength squared. A comparison with experimental data on flicker noise measurements in continuous metal films is made.

DC offset and high flicker noise are the main problems for the direct conversion CMOS mixer design. A novel even harmonic switching mixer implemented in a standard 0.18 μm CMOS process for applications in 2.45 GHz direct conversion receivers is proposed. The mixer circuit overcomes the problems of DC offset and high flicker noise. It achieves -8.24 dB gain, 5.2 dB DSB noise figure at 100 KHz, 17.25 dBm IIP3 and zero DC power consumption.

In this paper, a novel circuit method is proposed to reduce 1/f³ (close-in) phase noise in a cross-coupled LC Voltage Control Oscillator (VCO) by suppressing flicker noise power of the tail transistor. Using an added resistor between drain and gate of the tail transistor, that works as a negative feedback, the tail transistor flicker noise is suppressed, and therefore, the 1/f³ output phase noise is reduced by 5.7dB. Also, the added resistor helps in better tail current shaping for phase noise reduction. The proposed oscillator is designed in a 0.18$\mu$m CMOS technology with 1.8V supply and 3.6mW power consumption. Post-layout simulations predict a phase noise of $-104$dBc/Hz for the proposed oscillator at 100KHz offset from 3.1GHz carrier frequency. Mathematical analysis is included in the paper for confirmation of the phase noise performance enhancement. The Figure of Merit (FOM) of the proposed oscillator is 188.3 and 190.6dBc/Hz at 100KHz and 1MHz offsets, respectively.

A Sigma-Delta modulator (SDM) realized with a fully differential third-order single-loop cascaded integrator feedforward (CIFF) architecture is proposed. A pair of low-frequency chopper switches are nested outside the chopper amplifier to further reduce the residual offset voltage. To reduce the power consumption and ensure linearity, a high-speed dynamic comparator is also used to implement a one-bit quantizer. The proposed architecture and the corresponding functionality are first simulated in MATLAB Simulink at the behavioral level. The results show that the designed modulator has an SNDR of 124.9dB corresponding to an ENOB of 20.46 bits at a clock frequency of 256kHz and 312.5Hz input with a differential-mode voltage of 700mV sinusoidal waveform. Based on SMIC 180nm/1.8V standard CMOS process on the Cadence platform, the subcircuit-level simulation is also performed, while the result shows that the proposed modulator can effectively achieve 115.52dB SNDR, 18.90-bit ENOB, and 8.40mW power consumption, which correspond to FoM${}_{\mathrm{\text{W}}}$ and FoM${}_{\mathrm{\text{schreier}}}$ of 0.067pJ/step and 163.27dB, respectively. The proposed modulator shows a significant advantage to be applied for high-precision analog-to-digital conversion applications such as high-quality equipment for audio, ECG and EEG signal sensing.

Large-scale simulations and analysis of the original powers of 2 geometric source sum algorithm for simulating $1/f$ noise confirm that it provides a reasonably accurate approximation to an exact $1/f$ spectral density with a Gaussian amplitude distribution over any arbitrarily large frequency range. This incremental algorithm is computationally efficient with a computation time, after initialization, that varies linearly with the number of samples generated. A new variation allows non-integer and random ratios for the geometric sequence that reduces variations about the exact power-law spectral density and, by varying individual source amplitudes, produces generalized $1/f^{\beta }$ noises.

As was pointed out in some recent papers, the fluctuations in the secondary particle distribution of extensive air showers at observation level exhibit a complex structure which can be interpreted as a white noise plus a 1/f noise. The resulting coloured noise fits very well into the framework of the universal multitractal theory. In this paper we compare the e⁺ and e^- density fluctuations generated by different primary cosmic rays, namely, high energy γ rays, protons, and helium, oxygen and iron nuclei, and the universal multifractal parameters for all these primaries are calculated for several samples. The performed analysis reveals that the Levy index and the mean codimension depend monotonically on the mass of the primary cosmic ray. Some future applications of the multifractal properties of extensive air showers are suggested.

The power spectral density of low frequency resistance fluctuation in heterocyclic conducting polymer thin film resistors was measured at various temperatures and bias current values. An accurate calculation of the background noise was performed in order to correct the measured power spectral densities. A parameter obtained normalizing the voltage power density to the sample volume and d.c. bias is used to compare the tested conducting polymers with various materials used for resistors fabrication.

Low-frequency noise in MOSFETs is considered to originate from two distinctive sources: Random Telegraph Signal caused by carrier traps at the border of the SiO₂/Si interface and 1/f fluctuation due to inherent nature of lattice scattering in a Si crystal. It is very important to distinguish these two mechanisms. Relative amplitude of RTS and 1/f noise depends on the number of carriers under the gate electrode, which makes it channel size as well as gate-bias dependent. In this paper, we discuss the dependence of the amplitudes of RTS and 1/f noise in MOSFETs on sample geometry and gate bias condition. We discuss low-frequency noise reduction by utilizing low electron-temperature plasma for gate oxidation as well.

Spectra estimation in the field of low frequency noise measurements (LFNMs) is almost always performed by resorting to Discrete Fourier Transform (DFT) based spectrum analyzers. In this approach, the input signal is sampled at a proper frequency f_s and the power spectrum of sequences of N samples at a time are calculated and averaged in order to obtain an estimate of the spectrum at discrete frequency values f_k = kΔf, where the integer k is the frequency index and Δf = f_s/N is the frequency resolution. As the number of average increases, the statistical error, which is inversely proportional to the resolution bandwidth, can be made very small. However, if the spectrum of the signal is not a slowly changing function of the frequency, as in the case of 1/f^γ processes, spectra estimation by means of the DFT also results in systematic errors. In this paper we discuss the dependence of these errors on spectral parameters (the spectrum amplitude, the frequency f, the spectral exponent γ and the DC power) and on measurement parameters (the spectral window, the resolution bandwidth Δf and the instrumentation AC cutoff frequency). Quantitative expressions for the systematic errors are obtained that, besides helping in the interpretation of the results of actual LFNMs, can be used as a guideline for the optimization of the measurement parameters and/or for the estimation of the maximum accuracy that can be obtained in given experimental conditions. This quantitative analysis is particularly important since while we find that, in general, the systematic error at a given frequency f_k = kΔf can be made small if k is made large, which implies that Δf must be much smaller than f_k, possibly in contrast with the need for a Δf as large as possible in order to reduce the measurement time, the magnitude of the error depends on the selected spectral window. The role of the instrumentation AC cutoff frequency f_AC on the systematic error is also investigated and quantified and it is demonstrated that the error increases as f_AC reduces. This last result is very important since, often, f_AC is chosen much lower than the frequencies of interest and this choice may result in an increase of the systematic error.

The effect of ac hot-carrier stress on the performance of a wide locking range divide-by-4 injection-locked frequency divider (ILFD) is investigated. The ILFD was implemented in the TSMC 0.18 μm 1P6M CMOS process. The ILFD uses direct injection MOSFETs for coupling external signal to the resonators. Radio frequency (RF) circuit parameters such as oscillation frequency, tuning range, phase noise, and locking range before and after RF stress at an elevated supply voltage for 5 h have been examined by experiment. The measured locking range, operation range and phase noise after RF stress shows significant degradation from the fresh circuit condition.

The unclear physical origin of flicker noise in ultra-stable quartz oscillators is still limiting some practical metrological applications. In this paper, we study experimentally the possible correlations between Q-factor measurements at low temperature (4K) and the level of flicker noise at nominal operating temperature (353K). Results for 10 Stress-Compensated-cut (SC-cut) resonators with a 5MHz resonant frequency and different noise levels (some excellent) are presented and commented, for several overtones and anharmonic modes.

We present the results of gas sensing using the fluctuation-enhanced sensing method in selected two-dimensional materials (2DMs). We claim that gas sensing selectivity can be improved further by considering semiconducting two-dimensional materials doped by noble metal nanoparticles. The 2DMs’ structures exhibit some imperfections defined by their structure, occurring repeatedly there. These imperfections are adsorption–desorption centers responsible for gas-sensing properties and generating flicker noise of various intensities. We consider how these imperfections can be modulated and utilized for fluctuations-enhanced gas sensing. We propose the decoration of 2DMs by noble metal nanoparticles that impact flicker noise. Additionally, we consider utilizing localized surface plasmonic resonance induced by irradiation at selected wavelengths.

The low-frequency noise (LFN) in downscaled silicon transistors has become prominently large, and it occurs as a limiting factor for diverse applications. Considerable interest is paid to the “slow” (as compared to the operating frequency of the devices) noise. Therefore, we address the trends for LFN from an extensive analysis of data from many publications over a very long period. The impact of LFN on high-frequency device performance, the penalties associated with using composite materials, and unsolved issues are also discussed.

The elementary jumps in the electron current through conducting filaments of two nanometer-sized virtual memristor structures consisting of a contact of a conductive atomic force microscope probe to the Si₃N₄ layer with the thickness of 6nm deposited onto the $n^{++}$-Si(001) conductive substrates are investigated. These structures are: (S1) the Si₃N₄/Si film; (S2) the Si₃N₄/SiO₂/Si stack, a similar structure with 2nm SiO₂ sublayer between the film and the substrate. Usually, such investigations are performed by the analysis of the waveform of this current with the aim of extracting the random telegraph noise (RTN). Here, we develop a new indirect method, which is based on the measurement of the spectrum of the low-frequency flicker noise in the current without extracting the RTN. We propose that the flicker noise is caused by the motion (drift/diffusion) of nitrogen ions via vacancies within and around the filament. The number of these ions is estimated by taking into account the geometrical parameters of the filament. This allows us to estimate the root mean square magnitude $i_0$ of the current jumps, which are caused by random jumps of nitrogen ions, and the number M of these ions. This is fundamental for understanding the elementary mechanisms of the electron current flowing through the filament and the resistive switching in memristor devices.

In this paper, a correlated double sampling (CDS) technique is proposed in the design of a delta sigma analog-to-digital converter (ADC). These CDS techniques are very effective for the compensation of the nonidealities in switched-capacitor (SC) circuits, such as charge injection, clock feed-through, operational amplifier (op-amp) input-referred offset and finite op-amp gain. An improved compensation scheme is proposed to attain continuous compensation of clock feed-through and offset in SC integrators. Both high-speed and low-power operation is achieved without compromising the accuracy requirement. Also this CDS delta sigma ADC is the most promising circuit for analog to digital converter because this circuit reduces noise due to drift and low frequency noise such as flicker noise and offset voltage and also boosts the gain performance of the amplifier. Further, the simulation results of this circuit are verified on using a "cadence virtuoso tool" using spectre at 45 nm technology with supply voltage 0.7 V.

Nowadays tools based on Scanning Probe Methods (SPM) have become indispensable in a wide range of applications such as cell imaging and spectroscopy, profilometry, or surface patterning on a nanometric scale. Common to all SPM techniques is a typically slow working speed which is one of their main drawbacks. The SPM speed barrier can be improved by operating a number of probes in parallel mode. A key element when developing probe array devices is a convenient read-out system for measurements of the probe deflection. Such a read-out should be sufficiently sensitive, resistant to the working environment, and compatible with the operation of large number of probes working in parallel. In terms of fabrication, the geometrical uniformity i.e. the realisation of large numbers of identical probes, is a major concern but also the material choice compatible with high sensitivity, the detection scheme and the working environment is a challenging issue. Examples of promising applications using parallel SPM are dip-pen-nanolithography, data storage, and parallel imaging.