$$L_{1}$$-norm constrained normalized subband adaptive filter algorithm with variable norm-bound parameter and improved version

The \(L_{1}\)-norm constrained normalized subband adaptive filter with variable norm-bound parameter \((L_{1}\hbox {NCNSAF-V})\) algorithm and its variable step size version VSS-\(L_{1}\)NCNSAF-V are proposed in this paper, which are more superior to some existing algorithms in the sparse system. The proposed \(L_{1}\)NCNSAF-V is derived by using the Lagrange multiplier method, and the VSS-\(L_{1}\)NCNSAF-V is obtained by minimizing the statistical square of the Euclidean norm of the noise-free subband a posterior error vector. The simulation results demonstrate that the proposed algorithms achieve good performance.     

Study on the Effect of Mn,Zn, and Sb on Undercooling Behavior of Sn-Ag-Cu Alloys Using Differential Thermal Analysis

Differential thermal analysis (DTA) has been conducted on directionally solidified near-eutectic Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC), SAC \(+\) 0.2 wt.%Sb, SAC \(+\) 0.2 wt.%Mn, and SAC \(+\) 0.2 wt.%Zn. Laser ablation inductively coupled plasma mass spectroscopy was used to study element partitioning behavior and estimate DTA sample compositions. Mn and Zn additives reduced the undercooling of SAC from 20.4\(^\circ \hbox {C}\) to \(4.9^\circ \hbox {C}\) and \(2^\circ \hbox {C}\), respectively. Measurements were performed at cooling rate of \(10^\circ \hbox {C}\) per minute. After introducing 200 ppm \(\hbox {O}_2\) into the DTA, this undercooling reduction ceased for SAC \(+\) Mn but persisted for SAC \(+\) Zn.     

A Low-Voltage Fully Differential Pure Current Mode Current Operational Amplifier

In this paper a novel high-frequency fully differential pure current mode current operational amplifier (COA) is proposed that is, to the authors’ knowledge, the first pure MOSFET Current Mode Logic (MCML) COA in the world, so far. Doing fully current mode signal processing and avoiding high impedance nodes in the signal path grant the proposed COA such outstanding properties as high current gain, broad bandwidth, and low voltage and low-power consumption. The principle operation of the block is discussed and its outstanding properties are verified by HSPICE simulations using TSMC \(0.18\,\upmu \hbox {m}\) CMOS technology parameters. Pre-layout and Post-layout both plus Monte Carlo simulations are performed under supply voltages of \(\pm 0.75\,\hbox {V}\) to investigate its robust performance at the presence of fabrication non-idealities. The pre-layout plus Monte Carlo results are as; 93 dB current gain, \(8.2\,\hbox {MHz}\,\, f_{-3\,\text {dB}}, 89^{\circ }\) phase margin, 137 dB CMRR, 13 \(\Omega \) input impedance, \(89\,\hbox {M}\Omega \) output impedance and 1.37 mW consumed power. Also post-layout plus Monte Carlo simulation results (that are generally believed to be as reliable and practical as are measuring ones) are extracted that favorably show(in abovementioned order of pre-layout) 88 dB current gain, \(6.9\,\hbox {MHz} f_{-3\text {db}} , 131^{\circ }\) phase margin and 96 dB CMRR, \(22\,\Omega \) input impedance, \(33\,\hbox {M}\Omega \) output impedance and only 1.43 mW consumed power. These results altogether prove both excellent quality and well resistance of the proposed COA against technology and fabrication non-idealities.     

A PAPR reduction scheme based on a new spreading code in optical direct detection OFDM system

In this paper, we propose and experimentally demonstrate a peak-to-average power ratio (PAPR) reduction scheme based on a new spreading code in direct detection optical orthogonal frequency division multiplexing (OFDM) system. The new spreading code with low cross correlation and high auto-correlation can support \(2N+1\) users. Thus, \(2N+1\) users or data symbols can be transmitted over only N subcarriers. The experimental results show that, after transmission over 70 km single-mode fiber, at the bit error rate of \(10^{-3}\), with fiber launch power of 2.75 dBm, the receiver sensitivity can be improved 2.1 dB by using the proposed scheme based on new spreading code. The PAPR can be reduced about 4.6 dB, compared with the original OFDM signal at a complementary cumulative distribution function of \(10^{-4}\).     

Electrical Transport Mechanisms and Photoconduction in Undoped Crystalline Flash-Evaporated Lead Iodide Thin Films

The flash-evaporation technique was utilized to fabricate undoped 1.35-μm and 1.2-μm thick lead iodide films at substrate temperatures \( T_{\rm{s}} = 150 \)°C and 200°C, respectively. The films were deposited onto a coplanar comb-like copper (Cu-) electrode pattern, previously coated on glass substrates to form lateral metal–semiconductor–metal (MSM-) structures. The as-measured constant-temperature direct-current (dc)-voltage (\( I\left( {V;T} \right) - V \)) curves of the obtained lateral coplanar Cu-PbI₂-Cu samples (film plus electrode) displayed remarkable ohmic behavior at all temperatures (\( T = 18 - 90\,^\circ {\hbox{C}} \)). Their dc electrical resistance \( R_{\rm{dc}} (T \)) revealed a single thermally-activated conduction mechanism over the temperature range with activation energy \( E_{\rm{act}} \approx 0.90 - 0.98 \,{\hbox{eV}} \), slightly less than half of room-temperature bandgap energy \( E_{\rm{g}} \) (\( \approx \,2.3\, {\hbox{eV}} \)) of undoped 2H-polytype PbI₂ single crystals. The undoped flash-evaporated \( {\hbox{PbI}}_{\rm{x}} \) thin films were homogeneous and almost stoichiometric (\( x \approx 1.87 \)), in contrast to findings on lead iodide films prepared by other methods, and were highly crystalline hexagonal 2H-polytypic structure with c-axis perpendicular to the surface of substrates maintained at \( T_{\rm{s}} { \gtrsim }150^\circ {\hbox{C}} \). Photoconductivity measurements made on these lateral Cu-PbI₂-Cu-structures under on–off visible-light illumination reveal a feeble photoresponse for long wavelengths (\( \lambda > 570\,{\hbox{nm}} \)), but a strong response to blue light of photon energy \( E_{\rm{ph}} \) \( \approx \,2.73 \, {\hbox{eV}} \) (\( > E_{\rm{g}} \)), due to photogenerated electron–hole (e–h) pairs via direct band-to-band electronic transitions. The constant-temperature/dc voltage current–time \( I\left( {T,V} \right) - t \) curves of the studied lateral PbI₂ MSM-structures at low ambient temperatures (\( T < 50^\circ {\hbox{C}} \)), after cutting off the blue-light illumination, exhibit two trapping mechanisms with different relaxation times. These strongly depend on \( V \) and \( T \), with thermally generated charge carriers in the PbI₂ mask photogenerated (e–h) pairs at higher temperatures.     

Design and analysis of a feedback time difference amplifier with linear and programmable gain

This paper proposes a feedback time difference amplifier (FTDA) that achieves linear, controllable gain and changeable input range for different time difference gains. The proposed FTDA consists of two identical feedback output generators. The feedback output generator achieves a linear input–output transfer characteristic by employing two p-type keepers for time gain feedback control. Its validity was demonstrated using \({0.13}\, {\upmu \hbox {m}}\) SiGe BiCMOS process. The power consumption is \(91.54 \,{\upmu \hbox {W}}\) for the highest gain with input signals at \({2}\,\hbox {MHz}\). The gain can be controlled from 25.06 to \(734.9\,{\hbox {s/s}}\) within \(40 \,\hbox {ps}\) input time interval.     

Ab␣Initio Study of Aluminium Impurity and Interstitial-Substitutional Complexes in Ge Using a Hybrid Functional (HSE)

The results of an ab?initio modelling of aluminium substitutional impurity (\({\hbox {Al}}_{\rm Ge}\)), aluminium interstitial in Ge [\({\hbox {I}}_{\rm Al}\) for the tetrahedral (T) and hexagonal (H) configurations] and aluminium interstitial-substitutional pairs in Ge (\({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\)) are presented. For all calculations, the hybrid functional of Heyd, Scuseria, and Ernzerhof in the framework of density functional theory was used. Defects formation energies, charge state transition levels and minimum energy configurations of the \({\hbox {Al}}_{\rm Ge}\), \({\hbox {I}}_{\rm Al}\) and \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) were obtained for ?2, ?1, 0, \(+\)1 and \(+\)2 charge states. The calculated formation energy shows that for the neutral charge state, the \({\hbox {I}}_{\rm Al}\) is energetically more favourable in the T than the H configuration. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) forms with formation energies of ?2.37 eV and ?2.32 eV, when the interstitial atom is at the T and H sites, respectively. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) is energetically more favourable when the interstitial atom is at the T site with a binding energy of 0.8 eV. The \({\hbox {I}}_{\rm Al}\) in the T configuration, induced a deep donor (\(+\)2/\(+1\)) level at \(E_{\mathrm {V}}+0.23\) eV and the \({\hbox {Al}}_{\rm Ge}\) induced a single acceptor level (0/?1) at \(E_{\mathrm {V}}+0.14\) eV in the band gap of Ge. The \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) induced double-donor levels are at \(E_{\rm V}+0.06\) and \(E_{\rm V}+0.12\) eV, when the interstitial atom is at the T and H sites, respectively. The \({\hbox {I}}_{\rm Al}\) and \({\hbox {I}}_{\rm Al}{\hbox {Al}}_{\rm Ge}\) exhibit properties of charge state-controlled metastability.     

Electrochemical,Structural and Magnetic Analysis of Electrodeposited CoCu/Cu Multilayers: Influence of Cu Layer Deposition Potential

The electrochemical, structural and magnetic properties of CoCu/Cu multilayers electrodeposited at different cathode potentials were investigated from a single bath. The Cu layer deposition potentials were selected as \(-\,0.3,\,\hbox {V}\) \(-\,0.4\,\,\hbox {V}\), and \(-\,0.5\,\hbox {V}\) with respect to saturated calomel electrode (SCE) while the Co layer deposition potential was constant at \(-\,1.5\,\hbox {V}\) versus SCE. For the electrochemical analysis, the current-time transients were obtained. The amount of noble non-magnetic (Cu) metal materials decreased with the increase of deposition potentials due to anomalous codeposition. Further, current-time transient curves for the Co layer deposition and capacitance were calculated. In the structural analysis, the multilayers were found to be polycrystalline with both Co and Cu layers adopting the face-centered cubic structure. The (111) peak shifts towards higher angle with the increase of the deposition potentials. Also, the lattice parameters of the multilayers decrease from 0.3669 nm to 0.3610 nm with the increase of the deposition potentials from \(-\,0.3\,\hbox {V}\) to \(-\,0.5\,\hbox {V}\), which corresponds to the bulk values of Cu and Co, respectively. The electrochemical and structural results demonstrate that the amount of Co atoms increased and the Cu atoms decreased in the layers with the increase of deposition potentials due to anomalous codeposition. For magnetic measurements, the saturation magnetizations, \(M_s\) obtained from the magnetic curves of the multilayers were obtained as 212 kA/m, 276 kA/m, and 366 kA/m with \(-\,0.3\,\hbox {V}\), \(-\,0.4\,\hbox {V}\), and \(-\,0.5\,\hbox {V}\) versus SCE, respectively. It is seen that the \(M_s\) values increased with the increase of the deposition potentials confirming the increase of the Co atoms and decrease of the Cu amount. The results of electrochemical and structural analysis show that the deposition potentials of non-magnetic layers plays important role on the amount of magnetic and non-magnetic materials in the layers and thus on the magnetic properties of the multilayers.     

A 3.1–10.6 GHz UWB LNA Based on Self Cascode Technique for Improved Bandwidth and High Gain

In this work, we present a self cascode based ultra-wide band (UWB) low noise amplifier (LNA) with improved bandwidth and gain for 3.1–10.6 GHz wireless applications. The self cascode (SC) or split-length compensation technique is employed to improve the bandwidth and gain of the proposed LNA. The improvement in the bandwidth of SC based structure is around 1.22 GHz as compared to simple one. The significant enhancement in the characteristics of the introduced circuit is found without extra passive components. The SC based CS–CG structure in the proposed LNA uses the same DC current for operating first stage transistors. In the designed UWB LNA, a common source (CS) stage is used in the second stage to enhance the overall gain in the high frequency regime. With a standard 90 nm CMOS technology, the presented UWB LNA results in a gain \(\hbox {S}_{21}\) of \(20.10 \pm 1.65\,\hbox {dB}\) across the 3.1–10.6 GHz frequency range, and dissipating 11.52 mW power from a 1 V supply voltage. However, input reflection, \(\hbox {S}_{11}\), lies below \(-\,10\) dB from 4.9–9.1 GHz frequency. Moreover, the output reflection (\(\hbox {S}_{22}\)) and reverse isolation (\(\hbox {S}_{12}\)), is below \(-\,10\) and \(-\,48\) dB, respectively for the ultra-wide band region. Apart from this, the minimum noise figure (\(\hbox {NF}_{min}\)) value of the proposed UWB LNA exists in the range of 2.1–3 dB for 3.1–10.6 GHz frequency range with a a small variation of \(\pm \,0.45\,\hbox {dB}\) in its \(\hbox {NF}_{min}\) characteristics. Linearity of the designed LNA is analysed in terms of third order input intercept point (IIP3) whose value is \(-\,4.22\) dBm, when a two tone signal is applied at 6 GHz with a spacing of 10 MHz. The other important benefits of the proposed circuit are its group-delay variation and gain variation of \(\pm \,115\,\hbox {ps}\) and \(\pm \,1.65\,\hbox {dB}\), respectively.     

Sparse Least Logarithmic Absolute Difference Algorithm with Correntropy-Induced Metric Penalty

Sparse adaptive filtering algorithms are utilized to exploit system sparsity as well as to mitigate interferences in many applications such as channel estimation and system identification. In order to improve the robustness of the sparse adaptive filtering, a novel adaptive filter is developed in this work by incorporating a correntropy-induced metric (CIM) constraint into the least logarithmic absolute difference (LLAD) algorithm. The CIM as an \(l_{0}\)-norm approximation exerts a zero attraction, and hence, the LLAD algorithm performs well with robustness against impulsive noises. Numerical simulation results show that the proposed algorithm may achieve much better performance than other robust and sparse adaptive filtering algorithms such as the least mean p-power algorithm with \(l_{1}\)-norm or reweighted \(l_{1}\)-norm constraints.     

An efficient resource management scheme in light-trail networks

Light-trail, a framework proposed in the past few years, is generalized from the concept of lightpath, and its distinguishing features include bandwidth sharing and efficient bandwidth utilization. Performance of light-trail networks depends on the routing algorithm and the dynamic bandwidth allocation (DBA) scheme, and the former issue has been discussed extensively. In this work, we aim at the design of an efficient DBA scheme, named Demand and Delay-latency Aware with Two-round Deliberation \((\hbox {D}^{2}\hbox {ATD})\), to allocate bandwidth more accurately and efficiently in light-trail networks. In addition to DBA issue, \(\hbox {D}^{2}\hbox {ATD}\) includes a light-trail setup/release mechanism as well. As expected, the simulation results reveal superiority of \(\hbox {D}^{2}\hbox {ATD}\) in both blocking performance and delay performance. Although \(\hbox {D}^{2}\hbox {ATD}\) pays a price of control overhead for performance gain, it is still reasonable since the amount of control messages does not exceed the capacity of the control channel. It verifies that \(\hbox {D}^{2}\hbox {ATD}\) can properly employ the control channel to achieve excellent performance.     

A 0.36 μW/channel recorder for external ambulatory ECG recorders

There is an increasing demand for long-term ECG monitoring applications which are very low power, small size and capable of wireless data transmission. This paper presents an analog front-end and also modulator for long-term ECG recording purpose. The fully integrated system features three independent channels and a modulator. The analog front-end includes a voltage-to-time conversion and a tunable modulator to achieve a very low power consumption for wireless transmission of the data without analog to digital converter. The proposed system is designed and simulated in a \(0.18\,\upmu \hbox {m}\) CMOS technology and occupies only \(0.245\,\mathrm{mm}^{2}\). It can record ECG signal with 9.2-bit resolution while consuming only \(0.36\,\upmu {\mathrm{W}}\) per channel from a 0.9 V supply. Also, it can transmit data consuming just \(0.72\,{\upmu }\mathrm{W}\) per channel from a 0.9 V supply. The input referred noise of the readout channel is \(2.01\,\upmu {\mathrm{V}}_{{{\rm rms}}}\).     

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.     

New refractive index profiles of dispersion-flattened highly nonlinear fibers for future all-optical signal processing in wdm optical networks

In this paper, we demonstrate new dissimilar refractive index profiles for highly nonlinear ultra-flattened dispersion fibers with noteworthy effective area \((A_\mathrm{eff})\) for future optical signal processing. The newly proposed fibers named from Type 1 to Type 5 have a flattened dispersion over S, C, L and U bands. Predominantly, few-mode HNL-UFF fiber of Type 3 yields dispersion-flattened characteristics over a range of 250 nm of optical communication spectrum with a mere 0.2 ps/nm km variation in dispersion and a dispersion slope of \(0.0057\hbox { ps}/\hbox {nm}^{2}\) km due to the contribution of higher-order modes to the dispersion characteristics of the fiber. Moreover, it has a moderate nonlinear coefficient of \(8.03\hbox { W}^{-1}\,\hbox {km}^{-1}\). By modifying the refractive index profile of Type 3 fiber, Type 4 and Type 5 fibers are obtained in order to ensure single-mode operation, while the zero flattened dispersion characteristics of the fiber are compromised. Among the newly proposed fibers, Type 4 fiber offers a very low ITU-T cutoff wavelength of \(1.33~\upmu \hbox {m}\), whereas in the case of Type 5 fiber it is \(1.38~\upmu \hbox {m}\). Moreover, Type 4 and Type 5 fibers have good nonlinear coefficients of \(12.26\hbox { W}^{-1}\,\hbox {km}^{-1}\) and \(11.45\hbox { W}^{-1}\,\hbox {km}^{-1}\), respectively. By virtue of the proposed optimized index profile, an insensitive behavior toward bending is displayed by Type 3, Type 4 and Type 5 fibers. In addition, Type 4 fiber provides a better splice loss of 0.25 dB.     

Application of photonic crystal ring resonator nonlinear response for full-optical tunable add–drop filtering

In this paper, we investigate the application of Kerr-like nonlinear photonic crystal (PhC) ring resonator (PCRR) for realizing a tunable full-optical add–drop filter. We used silicon (Si) nano-crystal as the nonlinear material in pillar-based square lattice of a 2DPhC. The nonlinear section of PCRR is studied under three different scenarios: (1) first only the inner rods of PCRR are made of nonlinear materials, (2) only outer rods of PCRR have nonlinear response, and (3) both of inner and outer rods are made of nonlinear material. The simulation results indicate that optical power required to switch the state of PCRR from turn-on to turn-off, for the nonlinearity applied to inner PCRR, is at least \(2000\, \hbox {mW}{/}\upmu \hbox {m}^{2}\) and, for the nonlinearity applied to outer PCRR, is at least \(3000\, \hbox {mW}{/}\upmu \hbox {m}^{2}\) which corresponds to refractive index change of \(\Delta n_\mathrm{NL }= 0.085\) and \(\Delta n_\mathrm{NL }= 0.15\), respectively. For nonlinear tuning of add–drop filter, the minimum power required to 1 nm redshift the center operating wavelength \((\lambda _{0} = 1550\, \hbox {nm})\) for the inner PCRR scenario is \(125\, \hbox {mW}{/}\upmu \hbox {m}^{2}\) (refractive index change of \(\Delta n_\mathrm{NL}= 0.005)\). Maximum allowed refractive index change for inner and outer scenarios before switch goes to saturation is \(\Delta n_\mathrm{NL }= 0.04\) (maximum tune-ability 8 nm) and \(\Delta n_\mathrm{NL }= 0.012\) (maximum tune-ability of 24 nm), respectively. Performance of add–drop filter is replicated by means of finite-difference time-domain method, and simulations displayed an ultra-compact size device with ultra-fast tune-ability speed.     

An Accurate and Very Low Complexity LMMSE Channel Estimation Technique for OFDM Systems

In this paper, we propose a very low linear minimum mean square error (LMMSE) channel estimation technique for orthogonal frequency division multiplexing (OFDM) systems. The conventional LMMSE, based on the autocorrelation channel matrix, requires \(O(N_P^3)\) operations (\(N_P\) represents the total number pilot in one OFDM symbol). By exploiting the structure of the channel autocorrelation matrix, we propose a very low complexity LMMSE channel estimator which requires only \(O(N_PlogN_P)\) operations. Simulation results show that the proposed technique yields the same performances as well as the classical LMMSE in terms of bit error rate and mean square error.     

Error performance of optically preamplified hybrid BPSK-PPM systems with transmitter and receiver imperfections

In this paper, we investigate the impact of the transmitter finite extinction ratio and the receiver carrier recovery phase offset on the error performance of two optically preamplified hybrid M-ary pulse position modulation (PPM) systems with coherent detection. The first system, referred to as PB-mPPM, combines polarization division multiplexing (PDM) with binary phase-shift keying and M-ary PPM, and the other system, referred to as PQ-mPPM, combines PDM with quadrature phase-shift keying and M-ary PPM. We provide new expressions for the probability of bit error for PB-mPPM and PQ-mPPM under finite extinction ratios and phase offset. The extinction ratio study indicates that the coherent systems PB-mPPM and PQ-mPPM outperform the direct-detection ones. It also shows that at \(P_b=10^{-9}\) PB-mPPM has a slight advantage over PQ-mPPM. For example, for a symbol size \(M=16\) and extinction ratio \(r=30\) dB, PB-mPPM requires 0.6 dB less SNR per bit than PQ-mPPM to achieve \(P_b=10^{-9}\). This investigation demonstrates that PB-mPPM is less complex and less sensitive to the variations of the offset angle \(\theta \) than PQ-mPPM. For instance, for \(M=16\), \(r=30\) dB, and \(\theta =10^{\circ }\) PB-mPPM requires 1.6 dB less than PQ-mPPM to achieve \(P_b=10^{-9}\). However, PB-mPPM enhanced robustness to phase offset comes at the expense of a reduced bandwidth efficiency when compared to PQ-mPPM. For example, for \(M=2\) its bandwidth efficiency is 60 % that of PQ-mPPM and \(\approx 86\,\%\) for \(M=1024\). For these reasons, PB-mPPM can be considered a reasonable design trade-off for M-ary PPM systems.     

Design considerations of CMOS active inductor for low power applications

Previous studies have shown that \(g_m/I_D\) (transconductance-to-drain-current) ratio based design is useful for optimizing analog circuits. In this paper, we explore challenges associated with designing a low-power active inductor. We focus in particular on sizing issues that arise as the transistor speed is maximized and the current consumption is minimized. Finally, we apply the results to design an amplifier integrated with an active inductor in \(0.18\,\upmu \hbox{m}\) CMOS process and show that by systematically working through sizing issues, a \(10\,\upmu \hbox{A}\) sub GHz amplifier can be designed.     

Low Voltage High Output Impedance Bulk-Driven Quasi-Floating Gate Self-Biased High-Swing Cascode Current Mirror

A low voltage self-biased high-swing cascode current mirror using bulk-driven quasi-floating gate MOSFET is proposed in this paper. The proposed current mirror bandwidth and especially the output impedance show a significant improvement compared to prior arts. The current mirror presented is designed using bulk-driven and bulk-driven quasi-floating gate N-channel MOS transistors, which helped it to operate at very low supply voltage of \({\pm }0.2\,\hbox {V}\). To achieve high output resistance, the current mirror uses regulated cascode stage followed by super cascode architecture. The small-signal analysis carried out proves the improvement achieved by proposed current mirror. The current mirror circuit operates well for input current ranging from 0 to \(250\,{\upmu }\mathrm{A}\) with good linearity and shows the bandwidth of 285 MHz. The input and output resistances are found as \(240\,\Omega \) and \(19.5\,\hbox {G}\Omega \), respectively. Further, the THD analysis and Monte Carlo simulations carried prove the robustness of proposed current mirror. The complete analysis is done using HSpice on UMC \(0.18\,\upmu \mathrm{m}\) technology.     

An Accurate Performance Analysis for Regenerative Multi-hop Relaying in Wireless Networks Over Composite Multipath/Shadowed Fading

This paper presents and evaluates the performance of wireless networks that utilize the decode-and-forward relay. This multi-hop relaying scheme communicates over Extended Generalized-\({\mathcal {K}}\) (\(\hbox {EG}{\mathcal {K}}\)) composite fading channels to create performance evaluation. To this effect, new exact and easy to compute formulas for several performance metrics are derived. More specifically, new and exact-form mathematical formulas are derived for the cumulative distribution function, the generalized moments of the overall end-to-end signal-to-noise ratio, the outage probability (\({\hbox {P}}_{\text{out}}\)), the ergodic capacity (\({\mathcal {C}}_{\text{Ergodic}}\)), the moment generating function, and the average error probability (\({\hbox {Pr(e)}}\)) for different modulation schemes. Moreover, we carried out a series of computer simulation experiments in order to testify the accuracy of the derived framework. Finally, we discussed the impact of different parameters including fading/shadowing parameters, transmitted power and the number of hops on the derived expressions.