Low-voltage low-power fully-integratable automatic gain controls

This paper discusses the design of low-voltage low-power fully-integratable automatic gain controls. Four different AGCs are presented, all consisting of three elementary building blocks: a controlled amplifier, a comparator and a voltage follower. Their design is treated separately. As an example, the final section describes an automatic gain control for hearing instruments, realized in a bipolar process.     

Effect of wet chemical substrate pretreatment on the growth behavior of Ta(N) films deposited by thermal ALD

The deposition of ultra thin Ta(N) films by ALD is a possibility to achieve conformal film thickness and suitable step coverage for microelectronic applications. Due to the sorption of a precursor molecule to the substrate surface, the chemical interface conditions are important. In the present study selected substrate pretreatments were investigated by in situ XPS and spectroscopic ellipsometry in reference to the amount of carbon containing contamination and oxygen and in reference to the ALD growth rate of Ta(N) films. Furthermore, surface roughness was measured by AFM and will be discussed in dependence on the individual pretreatment and the ALD Ta(N) cycle number.     

CMOS射频集成电路ESD保护的挑战

随着集成电路(IC)T艺进入深亚微米水平,以及射频(Radi0.Frequency,RF)IC工作频率向数千兆赫兹频段迈进,片上防静电泄放(ESD)保护设计越来越成为RF IC设计的挑战.产生这一挑战的关键原因在于ESD保护电路和被保护的RF IC核电路之间存在着不可避免的复杂交互影响效应.本文讨论了RF ESD保护的研究和设计领域的最新动态,总结了所出现的新挑战、新的设计方法和最新的RF ESD保护解决方案.     

Design rules for an integratable low-power amplifier/filter combination

In this paper design rules for a circuit topology in which there is an inseparable combination of an amplifier and a filter characteristic, are presented. By intentionally using the capacitance of an already present input sensor for the filtering, the total required integrated capacitance is much less than that in circuits, which have a separately designed amplifier and filter function. Consequently, it is possible to have the advantage of a better integratability. Moreover, less complexity in the design is achieved. The presented circuit shows a current-to-voltage conversion and an inherently controllable second-order low-pass filter characteristic. A discrete realization has been designed to test the circuit. This circuit operates down to a 1 V supply voltage and the transfer shows a 1.8 M currentto-voltage conversion with a bandwidth of 6 kHz. Measurement results of this circuit show that a 63 dB dynamic range can be achieved with a total required integrated capacitance of only 31 pF.     

Highly stable 68-fs pulse generation from a stretched-pulse Yb/sup 3+/-doped fiber laser with frequency shifted feedback

We report on the development of a passively mode-locked and highly-stable stretched pulse laser based on Yb/sup 3+/-doped silica fiber. Mode-locking is achieved by nonlinear polarization evolution coupled with the frequency-shifted feedback technique for ensuring robust self-starting. The Fabry-Perot (F-P) cavity incorporates also a diffraction grating pair to compensate for the normal dispersion of the fiber. The laser generates chirped pulses with energies of 100 pJ at a repetition rate of 23 MHz (2.3 mW average power) around 1055 nm which were subsequently compressed to near-bandwidth-limited pulses of 68 fs duration.     

Projection or Persuasive Press? Contrary Effects of Personal Opinion and Perceived News Coverage on Estimates of Public Opinion

This study explores the effects of personal opinion and perceived media content on individuals' assessments of public opinion, as well as the curious phenomenon that, although people perceive public agreement with their own point of view, they tend to see press coverage as disagreeable. One hypothesis, based on theories of projection of personal opinion, predicts that people will see public opinion as much like their own, but a contrary outcome is suggested by 2 interrelated hypotheses, the hostile media effect and the persuasive press inference. Data were collected on 4 issues from a large, representative national sample and provided evidence for all 3 effects. Projection received the most consistent support, but findings indicate that this assimilation effect can be substantially offset by media coverage seen as both disagreeable and influential.     

Remote plasma etching of titanium nitride using NF3/argon and chlorine mixtures for chamber clean applications

To avoid plasma induced erosion of chamber hardware, the application of remote plasma sources to activate the etch gases was introduced. We present results on the etch behaviour of titanium nitride (TiN) using mixtures of NF₃, Cl₂ and argon. The gas mixture was excited in a remote plasma source and then routed through a reaction chamber to study the etch behaviour of TiN samples which simulate the situation at the chamber walls. The dependency of the TiN etch rate on temperature, gas flow, composition and pressure was examined. While the temperature (studied in the range 25-300 °C) turned out to be the most sensitive parameter, the general etch rate was mainly dependent on the availability of atomic fluorine. Etch products and NF₃/Cl₂ dissociation have been monitored by quadrupole mass spectrometry and infrared spectroscopy. While NF₃ showed a high decomposition up to 96%, chlorine decomposition was not observed. However the addition of chlorine increased the etch rates up to 260% in the low pressure/low temperature regime. Surface effects of chlorine addition are indicated by X-Ray Photoelectron Spectrometry and REM surface analysis.     

k‐strong privacy for radio frequency identification authentication protocols based on physically unclonable functions

This paper examines Vaudenay's privacy model, which is one of the first and most complete privacy models that featured the notion of different privacy classes. We enhance this model by introducing two new generic adversary classes, k‐strong and k‐forward adversaries where the adversary is allowed to corrupt a tag at most k times. Moreover, we introduce an extended privacy definition that also covers all privacy classes of Vaudenay's model. In order to achieve highest privacy level, we study low cost primitives such as physically unclonable functions (PUFs). The common assumption of PUFs is that their physical structure is destroyed once tampered. This is an ideal assumption because the tamper resistance depends on the ability of the attacker and the quality of the PUF circuits. In this paper, we have weakened this assumption by introducing a new definition k‐resistant PUFs. k‐PUFs are tamper resistant against at most k attacks; that is, their physical structure remains still functional and correct until at most k^th physical attack. Furthermore, we prove that strong privacy can be achieved without public‐key cryptography using k PUF‐based authentication. We finally prove that our extended proposal achieves both reader authentication and k‐strong privacy. Copyright © 2014 John Wiley & Sons, Ltd.     

Laser-Printed Plasmonic Metasurface Supporting Bound States in the Continuum Enhances and Shapes Infrared Spontaneous Emission of Coupled HgTe Quantum Dots

In order to advance the development of quantum emitter-based devices, it is essential to enhance light-matter interactions through coupling between semiconductor quantum dots with high quality factor resonators. Here, efficient tuning of the emission properties of HgTe quantum dots in the infrared spectral region is demonstrated by coupling them to a plasmonic metasurface that supports bound states in the continuum. The plasmonic metasurface, composed of an array of gold nanobumps, is fabricated using single-step direct laser printing, opening up new opportunities for creating exclusive 3D plasmonic nanostructures and advanced photonic devices in the infrared region. A 12-fold enhancement of the photoluminescence in the 900–1700 nm range is observed under optimal coupling conditions. By tuning the geometry of the plasmonic arrays, controllable shaping of the emission spectra is achieved, selectively enhancing specific wavelength ranges across the emission spectrum. The observed enhancement and shaping of the emission are attributed to the Purcell effect, as corroborated by systematic measurements of radiative lifetimes and optical simulations based on the numerical solution of Maxwell's equations. Moreover, coupling of the HgTe photoluminescence to high quality factor modes of the metasurface improves emission directivity, concentrating output within an ≈20° angle.