Frequency limitation of metal-oxide varistors

The frequency possibilities of metal-oxide varistors are investigated. An expression is deduced for the limiting frequency f _o of their application. It is also expressed in terms of the catalogue data of commercial varistors or by means of the parameters or the ceramic material. An evaluation of the f _o of ZnO, SnO₂ and SrTiO₃ varistors is made. For ZnO devices f _o has a maximum value (3-5) kHz, but for SrTiO₃ it is 100 Hz. The structure of the varistor's ceramic determines the limiting frequency of their application.     

Jitter and phase noise of ADPLL due to PSN with deterministic frequency

In this article, jitter and phase noise of all-digital phase-locked loop due to power supply noise (PSN) with deterministic frequency are analysed. It leads to the conclusion that jitter and phase noise heavily depend on the noise frequency. Compared with jitter, phase noise is much less affected by the deterministic PSN. Our method is utilised to study a CMOS ADPLL designed and simulated in SMIC 0.13?µm standard CMOS process. A comparison between the results obtained by our method and those obtained by simulation and measurement proves the accuracy of the predicted model. When the digital controlled oscillator was corrupted by PSN with 100?mVpk-pk, the measured jitters were 33.9?ps at the rate of f_G?=?192?MHz and 148.5?ps at the rate of f_G?=?40?MHz. However, the measured phase noise was exactly the same except for two impulses appearing at 192 and 40?MHz, respectively.     

Frequency Selectivity via Inner Boundary Conditions for A Self-Powered Multiresonant Acoustic Sensing Array with Broad Bandwidth

This study investigates and proposes innovative approaches to achieve frequency selectivity within a limited space. Traditional multiresonant acoustic devices use individual sensing elements of varying sizes to achieve resonance frequency (f_r), leading to an inability to sense focused acoustic waves, unlike the human ear. A miniaturized, self-powered artificial basilar membrane that incorporates multiresonant features is introduced. Multiple f_r of the diaphragms are developed using inner boundary conditions (iBCs) defined by an adjustable micropatterned elastomeric support (µ-support) and a porous nanofiber (NF) mat. This new approach offers the advantage of all-in-one fabrication, eliminating the need for device area variation or an additional rigid frame typically required in conventional multiresonant acoustic devices. The efficacy of the iBCs in shifting f_r within the vocal frequency ranges is verified via a laser Doppler vibrometer, simulation, and triboelectric output. With its self-powering capabilities based on triboelectric principles, this artificial basilar membrane holds promise for accurately recognizing musical and vocal signals with specific frequency characteristics. With four different iBCs in a total device area of 23 × 23 mm², a tunable four-channel system with f_r ranging from 400 to 3000 Hz is achieved. This advancement enables the sensing of focused acoustic waves, simulating the functionality of an artificial human ear model.     

Sommerfeld wave (<Emphasis Type="Italic">E</Emphasis><Subscript>00</Subscript> wave) propagating along the cylindrical conductor with a large radius

The technique of solving the dispersion equation for the E ₀₀ wave (Sommerfeld wave), which propagates through a cylindrical conductor with large radius a and finite conductivity σ₁ in the presence of a surrounding lossy dielectric, has been developed. The presented numerical results are obtained by calculating a cylinder with the earth radius and sea water parameters at the frequencies f = 0.0500−0.9554 MHz. It is shown that f ₀ = 0.9554 MHz is the limiting frequency.     

Fault diagnosis under a limited-fault assumption and limited test-point availability

This paper describes a method of fault diagnosis for large interconnected circuits in which the number of faults is limited to, say,n _f where it is possible thatn _f exceeds the number of output measurements,n _o. The problem and its solution are formulated in the context of a frequency domain tableau based on the component connection model of a circuit/system. The paper describes Jacobian tests for diagnosability whenn _fn _o and states a full parameter diagnosability test as a corollary to the main theorem. An algorithm is developed for the identification of faulty parameters in this limited fault case. Finally, examples, including a 26-parameter video-amplifier circuit, illustrating the technique are given.     

基于电学拓扑结构拓展FBAR滤波器带宽研究

该文研究了一种薄膜体声波谐振器(FBAR)采用并联电感和外匹配电路的拓扑结构实现宽带滤波的方法。使用Comsol软件对FBAR进行三维结构仿真,并提取最优电极形状(变迹五边形)对应曲线到ADS中联合外匹配电路进行频带拓展,外匹配电路中的电感L_s取值直接影响滤波器带宽。经调节,最终在谐振器串联谐振频率f_s=1.97 GHz,并联谐振频率f_p=2.03 GHz的情况下实现了21.15%的相对带宽,此时对应的3 dB带宽为419 MHz, 1 GHz处的带外抑制为11.616 dB。     

Low sensitivity multifunction active circuits using CFA-based supercapacitor

Some new current feedback amplifier (CFA)-based active Resistance–Capacitance (RC) circuits are presented for the realization of an ideal grounded supercapacitor (Y(s)?=?s ² D) type Frequency Dependent Negative Resistance (FDNR). The D-element is then resonated with additional RC sections to derive multifilter function circuits. The filter function have been tested for continuous resonant frequency (f ₀) tunability in a range of 30?KHz?≤?f ₀?≤?300?KHz with high quality (1?Q?相似文献   

Experimental study and empirical evaluation of carrier compression and third order intermodulation products of unequal carriers in a communication satellite transponder

Carrier compression and third order intermodulation products of two and three unequal carriers have been studied experimentally using a 36 MHz wide C-band transponder of INSAT-1B satellite. From the experimental data, empirical relations for carrier compression for two unequal carriers have been derived, which agree with the measured data within ±0.5 dB. The empirical relations for carrier compression derived for two unequal carriers have been extended to three unequal carriers and good correlations with measured data have been obtained. Empirical relations for third order intermodulation products of two and three (f₁+f₂-f₃ type) unequal carriers have also been derived.     

The Effect of Nanotube Content and Orientation on the Mechanical Properties of Polymer–Nanotube Composite Fibers: Separating Intrinsic Reinforcement from Orientational Effects

We have measured the mechanical properties of coagulation‐spun polymer–nanotube composite fibers. Both the fiber modulus, Y, and strength, σ_B, scale linearly with volume fraction, V_f, up to V_f ～10%, after which these properties remain constant. We measured dY/dV_f = 254 GPa and dσ_B/dV_f = 2.8 GPa in the linear region. By drawing fibers with V_f < 10% to a draw ratio of ～60%, we can increase these values to dY/dV_f = 600 GPa and dσ_B/dV_f = 7 GPa. Raman measurements show the Herman's orientation parameter, S, to increase with drawing, indicating that significant nanotube alignment occurs. Raman spectroscopy also shows that the nanotube effective modulus, Y_Eff, also increases with drawing. We have calculated an empirical relationship between the nanotube orientation efficiency factor, η_o, and S. This allows us to fit the data for Y_Eff versus η_o, showing that the fiber modulus scales linearly with η_o, as predicted theoretically by Krenchel. From the fit, we estimate the nanotube modulus to be; Y_NT = 480 GPa. Finally, we show that the fiber strength also scales linearly with η_o, giving an effective interfacial stress transfer of τ = 40 MPa and a nanotube critical length of l_c=1250 nm. This work demonstrates the validity of the Cox‐Krenchel rule of mixtures and shows that continuum theory still applies at the near‐molecular level.     

Selective Filters and Sinusoidal Oscillators Using CFA Transimpedance Pole

Using a single current feedback amplifier (CFA) device, two new variable frequency sinusoidal RC oscillators are presented. The transadmittance pole of the device (AD-844) has been utilized in the design for generating sine wave signals covering a range of 1 MHz≤f ₀≤31 MHz. Under open-loop conditions, both circuits exhibit resonance characteristics at moderate Q-values (1≤Q≤9). These responses have been experimentally verified with hardware circuit implementation and PSPICE macromodel simulation.     

<Emphasis Type="Italic">f</Emphasis><Subscript>T</Subscript> × <Emphasis Type="Italic">BV</Emphasis><Subscript>cbo</Subscript> product modeling for SiGe:C HBTs

The specific aspects of SiGe:C HBT process and device simulation using TCAD are discussed. Cut-off frequency f _T and collector junction breakdown voltage BV _cbo dependences on carbon concentration in SiGe base area are investigated. The boron and carbon profiles in SiGe base are obtained to provide a trade-off between gain, cut-off frequency and break-down voltage. High values of f _T × BV _cbo product were achieved.     

Robust Low Power CMOS Single-Ended to Fully-Balanced Converter Circuits

In this paper two novel single-ended-input fully-balanced-output circuits (SFC), namely unbuffered and buffered SFCs, are proposed for input interface to fully balanced signal processing systems. The unbuffered SFC overcomes the drawback of uncontrollable process variations of resistors and generate well-controlled process invariant common mode output voltage, V _o,com . The adopted active current common mode feedback compensation makes this possible. Simulations using MOSIS 2 m N-well process and a 3 V supply, show that with ±100% variation, V _o,com only varies by less than ±2%. In addition, it is shown that V _o,com is accurately controlled by a preset DC voltage. On the other hand, the buffered SFC adopts a novel body effect-free class AB buffer so as to have low standby power consumption but high current driving capability. It is implemented without resistors and common-mode feedback circuitry. Measurement results from a 1.2 m N-well CMOS chip indicate a bandwidth of 5.5 MHz while driving a 40 pF load with a supply voltage of ±1.5 V. The circuit is capable of supplying more than 3 mA of output current while consuming 1.1 mW of standby power. The THD is less than –55 dB at 1 KHz and the phase error is less than 2° for frequencies up to 1 MHz.     

Design and performance analysis of wrap-gate CNTFET-based ring oscillators for IoT applications

In recent years, usage of novel non-Si materials as the gate channel region in next generation of field effect transistors, including carbon nanotubes, have been in the spotlight of nanoelectronics research due to astounding carrier transport and I-V characteristics. These properties make them a highly suitable platform in modern radio frequency applications. Therefore, the aim of this work is to design and investigate the performance of current-starved and skewed ring oscillators based on ballistic carbon nanotube transistors (CNTFETs). In this work, we have utilized wrap-gate structure to have a better electrostatics control and mitigate the gate leakage current. All the CNTs in both n-type and p-type transistors have 0.9 nm diameter and an array of CNTs have been exploited in the gate region to achieve low-power and high-performance operation. The simulation results demonstrate that the proposed CNTFET-based ring oscillators have sub-100μW power consumption (P_{current-starved} = 6.011 μW, P_low-skew = 67.2 μW, and P_high-skew = 23.5 μW) along with wide frequency tuning range (f_{current-starved} = 0.202 GHz − 1.205 GHz, f_low-skew = 0.361 GHz − 2.137 GHz, and f_high-skew = 0.335 GHz − 2.38 GHz) which are suitable for internet of thing (IoT) devices operating from 100 MHz to 5.8 GHz. Finally, based on the simulation results, we have emphasized that the CNTFET-based skewed ring oscillators are suitable for high-speed purposes, while the CNTFET-based current-starved ring oscillator is recommended for low-power and high-swing applications.     

Toward Faster Organic Photodiodes: Tuning of Blend Composition Ratio

The ability of a light-sensor to detect fast variation in incident light intensity is a vital feature required in imaging and data transmission applications. Solution-processed bulk heterojunction (BHJ) type organic photodiodes (OPDs) have gone through key developments, including dark current mitigation and longer linear dynamic range. In contrast, there has been less focus on increasing OPD response speed (f_–3dB). Here, bulk heterojunction OPDs based on electron-donating polymer poly[thiophene-2,5-diyl-alt-5,10-bis((2-hexyldecyl)oxy)dithieno[3,2-c:3′,2′-h][1,5]naphthyridine-2,7-diyl] (or PTNT) and electron-accepting phenyl-C₇₁-butyric acid methyl ester (or PC₇₁BM) are reported. The intrinsic charge transport characteristics required for fast speed OPDs are discussed, and an analytical model for the same is developed. The OPDs present 0.8 MHz f_–3dB under no applied voltage bias for a typical blend ratio of 1:1 by weight. It is shown that balanced electron and hole mobility is a critical criterion for faster speed OPDs, which can be realized by tuning the composition ratio of the bulk heterojunction. By tuning PTNT and PC₇₁BM blend ratio, the f_–3dB was successfully raised by more than quadruple to 4.5 MHz. The findings provide a tool to set device architecture for faster next-generation light sensors.     

一种应用于无线局域网接收机的1.2伏双通道10位55nm CMOS流水线模数转换器

A power-efficient technique for pipeline analog-to-digital converters(ADCs) is proposed. By sharing amplifiers between I/Q channels, the power dissipation of the ADCs is reduced by almost one-half compared to conventional topologies, which makes this technique suitable for low-power direct-conversion WLAN receivers. A dual-channel ADC test chip is fabricated in 55 nm CMOS technology. The 10 bit ADC with on-chip reference generators dissipates 19.2 mW per channel from a 1.2 V supply. At an 80 MS/s sample rate, the measured spuriousfree dynamic range, signal-to-noise and distortion ratio, and corresponding effective number of bits are 69.5 dB, 56.8 dB and 9.14 bits with a 1 MHz input frequency(fin/, and 61.3 dB, 56.5 dB and 9.09 bits with a 15 MHz fin, respectively. The active area is 1.01 0.77 mm2.     

Channel current limitations in GaAs MESFETS

The maximum channel current, I_m, the maximum forward gate bias voltage, V_f, and the corresponding knee voltage, V_kf, play an important role in determining the maximum power handling capability of a GaAs MESFET. The definition of these parameters is given in a practical manner. Simple and yet accurate enough expressions for these parameters derived from a theoretical model are shown in terms of the geometrical and material parameters of the active channel of a device. A very simple expression for I_m obtained on an empirical basis is also shown. For the zero-gate-bias channel current, I_o, simple theoretical and empirical expressions are presented. Calculated values of I_m, V_f, V_kf and I_o using these expressions are in excellent agreement with their measured values for sample devices chosen from a variety of channel properties. A graphical presentation of I_m and that of the maximum channel-current enhancement ratio, I_m/I_o, are given as functions of basic channel parameters for practical purposes.     

Analysis of channel noise and threshold voltage in sos-MOS transistors in the temperature range of 77–300 K

A characterization is carried out for MOS transistors on sapphire on the basis of an analysis of the threshold voltage V_T and the channel noise current using the doping of the silicon (2 × 10¹⁵ cm^?3 to 6 × 10¹⁶ cm^?3) and the temperature (77–300 K) as parameters.The experimental values of V_T, as a function of the bulk potential V_BS, show that it is possible to deplete the silicon film fully for doping magnitudes less than 10¹⁶ cm^?3. The modelling of V_T vs. V_BS, using a relation derived for bulk Silicon devices, points to finite volume effects of the silicon.The analysis of the noise shows, at 300 K, an excess noise which follows a 1/f law for the Silicon film not fully depleted and a 1/f² law in the depleted case. On the other hand, at 77 K, this noise always shows a 1/f behaviour. The study of the noise as a function of temperature suggests that the traps of the Silicon-Sapphire interface become more active around room temperature than around 77 K. The thermal level is reached at about 1 MHz at room temperature for all devices, whereas at 77 K it is only observed for the higher doping devices.     

Role of nanoscale AlN and InN for the microwave characteristics of AlGaN/(Al,In)N/GaN-based HEMT

A new AlGaN/GaN-based high electron mobility transistor (HEMT) is proposed and its micro-wave characteristics are discussed by introducing a nanoscale AlN or InN layer to study the potential improvement in their high frequency performance. The 2DEG transport mechanism including various sub-band calculations for both (Al,In) N-based HEMTs are also discussed in the paper. Apart from direct current characteristics of the proposed HEMT, various microwave parameters such as transconductance, unit current gain (h ₂₁ = 1) cut-off frequency (f _t ), high power-gain frequency (f _max). Masons available/stable gain and masons unilateral gain are also discussed for both devices to understand its suitable deployment in microwave frequency range.     

Microwave Performance of AlGaN/GaN High-Electron-Mobility Transistors on Si/SiO2/Poly-SiC Substrates

The radiofrequency (RF) performance of AlGaN/GaN high-electron-mobility transistors (HEMTs) grown by molecular beam epitaxy (MBE) on Si-on-poly-SiC (SopSiC) substrates formed by the Smart-Cut^TM process is reported. This provides a low-cost, high-thermal-conductivity substrate for power applications. HEMTs with a 0.5 μm gate length show cutoff frequencies (f _T) of 18 to 27 GHz for gate-to-drain distances of 3 to 32 μm and a maximum frequency of oscillation (f _max) of 43 to 47 GHz. The f _max values are slightly lower than comparable devices on sapphire, SiC or Si alone. This approach looks promising for applications requiring cheap large-area substrates and better thermal management than provided by pure Si substrates alone.     

Study of process induced variability of germanium-pTFET in analog and RF domain

Germanium (Ge) tunnel field effect transistor (TFET) is considered to be an excellent solution to resolve the low on-currents issue of Silicon-based TFETs. Whereas, process variability in any low technology node devices (sub-100 nm) is a crucial subject of matter which affects the device reliability and dependability in advanced SoC applications. In this brief, we have investigated the two main process induced variability a) the thickness of the germanium body b) the thickness of gate oxide in Ge-pTFET using Sentaurus TCAD device simulation. The analysis is performed in complete analog domain along with the study of intrinsic RF performance parameters using small signal equivalent model with non-quasi static effect of the device under consideration. The process induced variability is estimated on the figure of merits (FOMs) such as drain current (I_ds), transconductance (g_m), output resistance (R_o), intrinsic gain (g_mR_o), unity-gain cutoff frequency (f_T), transit frequency of maximum available power gain (f_MAX), transport delay (τ_m), intrinsic resistance (R_gd) and intrinsic capacitances (C_gs, C_gd).