Authors:Maryamsadat Shokrekhodaei; Aminghasem Safarian; Mojtaba Atarodi Pages: 383 - 394 Abstract: A novel method of transmitter (TX) leakage cancellation is presented to improve the dynamic range of the receiver for wideband code division multiple access applications. The large TX leakage is attenuated within the low noise amplifier (LNA) output using a feed-forward path without any LNA noise figure degradation. A prototype has been designed and laid out in 0.18 μm CMOS technology. It achieves a maximum TX rejection of 18.5 dB with only 5.2 mA current consumption from 1.8 V supply voltage. LNA P-1dBCP (1 dB gain compression point) against TX leakage improves by more than 10 dB. Post layout simulations verify these results. Proposed structure dispels the requirement of off-chip surface acoustic wave filter. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1054-8 Issue No:Vol. 93, No. 3 (2017)

Authors:Yanghyo Kim; Wei-Han Cho; Yuan Du; Jason Cong; Tatsuo Itoh; Mau-Chung Frank Chang Pages: 395 - 413 Abstract: Impulse response of energy-efficient multiband RF-interconnect (MRFI) is analyzed to quantify its information capacity for transmitting digital data via various types of physical wires. Our analyses in frequency domain (also transferrable to time domain if needed) indicate that a baseband-equivalent impulse response can be established for MRFI under coherently communicated systems. We can further express such response in an explicit form for MRFI with low-pass transmission nature. It also reveals its distinct capability in signal equalization as a result of its RF-carrier down-conversion process. Furthermore, the analysis offers a guidance of how to construct baseband-equivalent impulse response when transmission lines contain non-ideal effects such as frequency notches and in-band ripples. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1058-4 Issue No:Vol. 93, No. 3 (2017)

Authors:Imen Ghorbel; Fayrouz Haddad; Wenceslas Rahajandraibe; Mourad Loulou Pages: 415 - 426 Abstract: Internet of things is a topic of rising interest and intensive research, where power consumption is one of its most relevant challenges. This article presents a new radiofrequency subthreshold ultra low power LC voltage controlled oscillator (VCO). A graphical inductor optimization approach has been proposed and used to design the LC VCO leading to high performances in terms of power consumption, chip area and phase noise. It uses the adaptive body biasing technique to ensure high immunity to process, voltage and temperature variations. Realized in a 130 nm CMOS technology, the VCO occupies a total area of 0.234 mm2. The measured frequency varies between 2.34 and 2.43 GHz. The post-layout simulation results show a phase noise of −116.1 dBc/Hz @1 MHz offset frequency, while the measured phase noise is −107.36 @1 MHz due to noisy measuring environment. The presented VCO provides a measured power consumption of only 168 μW from 0.6 V supply voltage, making it suitable for ultra low power applications. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1047-7 Issue No:Vol. 93, No. 3 (2017)

Authors:Venkata P. Yanambaka; Saraju P. Mohanty; Elias Kougianos Pages: 429 - 441 Abstract: In a typical design environment, semiconductor manufacturing variations are considered as challenges for nanoelectronic circuit design engineers. This has led to multi-front research on process variations analysis and its mitigations. As a paradigm shift of that trend the present article explores the use of semiconductor manufacturing variations for enhancing security of systems using FinFET technology as an example. FinFETs were introduced to replace high- \(\kappa \) transistors in nanoelectronic applications. From microprocessors to graphic processing units, FinFETs are being used commercially today. Along with the technological advancements in computing and networking, the number of cyber attacks has also increased. Simultaneously, numerous implementations of the Internet of Things are already present. In this environment, one small security flaw is enough to place the entire network in danger. Encrypting communications in such an environment is vital. Physical unclonable functions (PUFs) can be used to encrypt device to device communications and are the main focus of this paper. PUFs are hardware primitives which rely on semiconductor manufacturing variations to generate characteristics which are used for this purpose. Two different designs of a ring oscillator PUF are introduced, one with low power consumption trading off device performance and one high-performance trading off device power consumption. There is an 11% decrease in power consumption with the low power model along with a simple design and fabrication. Performance of the device can be increased with almost no increase in power consumption. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1053-9 Issue No:Vol. 93, No. 3 (2017)

Authors:Raqibul Hasan; Tarek M. Taha; Chris Yakopcic Pages: 443 - 454 Abstract: Memristor crossbar arrays carry out multiply–add operations in parallel in the analog domain which is the dominant operation in a neural network application. On-chip training of memristor neural network systems have the significant advantage of being able to get around device variability and faults. This paper presents a novel technique for on-chip training of multi-layer neural networks implemented using a single crossbar per layer and two memristors per synapse. Using two memristors per synapse provides double the synaptic weight precision when compared to a design that uses only one memristor per synapse. Proposed system utilizes a novel variant of the back-propagation (BP) algorithm to reduce both circuit area and training time. During training, all the memristors in a crossbar are updated in four steps in parallel. We evaluated the training of the proposed system with some nonlinearly separable datasets through detailed SPICE simulations which take crossbar wire resistance and sneak-paths into consideration. The proposed training algorithm trained the nonlinearly separable functions with a slight loss in accuracy compared to training with the traditional BP algorithm. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1051-y Issue No:Vol. 93, No. 3 (2017)

Authors:Guilherme S. Cardoso; Tiago R. Balen Pages: 455 - 466 Abstract: This paper presents an investigation on two important issues related to the application of enclosed layout transistor (ELT) to the design of analog building blocks: the performance impacts, related to the geometrical asymmetry and capacitances of drain and source terminals and the possible errors of commercial design tools when performing the layout versus schematic and layout extraction tasks. A common-source (CS) amplifier is considered as case study, to which the ELT layout technique is applied. SPICE simulations are performed, considering different methodologies to estimate the effective aspect ratio (W/L) of the ELT devices. The extracted equivalent W/L using a commercial design tool is compared with well-known mathematical models presented in the literature. Simulations were carried out considering three different channel lengths for the CS amplifier. The possibility of setting the transistor drain as inner or outer terminal of the ELT was also investigated. According to obtained results, considering a 0.18 µm technology, there may be significant performance differences, both in DC and AC behavior of the amplifier, and significant divergences of the extracted W/L, when compared to the analyzed models. Additionally, in order to improve the achievable aspect ratio range of square ELTs, we propose to use parallel and series associations of enclosed devices. Depending on the desired W/L, it is also possible to save silicon area with such associations. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1050-z Issue No:Vol. 93, No. 3 (2017)

Authors:Hua Tang Pages: 467 - 476 Abstract: In design of Continuous-time Delta-Sigma modulators, the feedback DAC (Digital-to-Analog Converter) is typically implemented with a switched current circuit. It is desired that these DAC current circuits provide constant current across clock cycles for each modulator output level. However, when Delta-Sigma modulators are implemented with Gm-C integrators, the DAC feedback current circuits are directly connected to the integrator outputs that may have high-swing voltages and this results in varying DAC feedback current. In this paper, we analyze the effect of feedback current variation caused by high-swing integrator output voltages in Delta-Sigma modulators built with Gm-C integrators. It is shown that feedback current variation may significantly degrade the performance of Delta-Sigma modulators mainly due to the non-linearity of current variation dependence on the integrator output voltage, while mismatch of current variation has minor effect. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1049-5 Issue No:Vol. 93, No. 3 (2017)

Authors:Supriyo Srimani; Manas Kumar Parai; Kasturi Ghosh; Hafizur Rahaman Pages: 477 - 488 Abstract: This paper presents a fault detection algorithm to detect parametric fault in linear and weakly non-linear analog circuits by Bhattacharyya measure, a statistical metric. Linear feedback shift register (LFSR) generated pseudo-random bit sequences are fed to digital-to-analog converter (DAC) to obtain random analog input stimuli for the circuit under test (CUT). Bhattacharyya coefficient is measured from the probability density function (PDF) of the output. The non-Gaussian auto-regressive model is used to estimate the PDF. Component tolerance is mapped into statistical space by Monte Carlo simulation. The proposed methodology is validated through three benchmark circuits: continuous-time low pass state variable filter circuit, fourth order low pass Chebyshev filter circuit and cascade amplifier. All the circuits are simulated with CADENCE Virtuoso using UMC-180nm technology. Defect screening is also measured with linear regression analysis. Detectability of the proposed method for parametric fault is reasonably large in comparison to functional test method. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1052-x Issue No:Vol. 93, No. 3 (2017)

Authors:Shweta Kumari; Maneesha Gupta Pages: 489 - 506 Abstract: A high transconductance Current Follower Transconductance Amplifier (CFTA) is proposed in this paper. The proposed CFTA consists of current follower and transconductance stage with NMOS cross-coupling to enhance the transconductance. The NMOS cross coupling stage forms negative transconductance which results in higher transconductance and wider tuning range without affecting its output swing and bandwidth performance. The proposed CFTA operates at ±0.6 V supply voltage, provides 8.5 mS transconductance and dissipates 1.7 mW power. To verify the high performance of proposed CFTA, a current mode quadrature oscillator and biquad filter have been designed and simulated. Cadence virtuoso schematic composer has been used to verify the performance of proposed CFTA and its applications with TSMC 0.18 µm technology parameters. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1036-x Issue No:Vol. 93, No. 3 (2017)

Authors:S. Rahmani; M. B. Ghaznavi-Ghoushchi Pages: 507 - 521 Abstract: Analog comparators are the basic circuit elements in analog to digital converters. In this paper, we present a high speed double-tail comparator with isomorphic latch-preamplifier pairs and tail bootstrapping. We used NAND gates because of its higher speed than the NOR gate, as SR-NAND-latch in second stage. The first stage is composed of two parts, preamplifier and voltage boosting block. Preamplifier utilized in a structure similar to latch, and voltages boosting increases the effective supply voltage in clock transition times, results in reduced delay. This results in a desirable speed at lower supply with reduced power consumption. The presented comparator is designed and simulated in both of 0.18-μm and 65-nm CMOS technologies. Simulation results in 0.18-μm show delay of proposed comparator reduced about 35% than conventional comparator. The proposed comparator operates correctly by 2.8 GHz at 1.1 V supply voltage with only 1.3 mW power. The simulation results in 65-nm CMOS technology show that delay and power consumption of isomorphic latch-preamplifier have significant reduction than the results in 180-nm. The proposed comparator is well-suited for mix-signal applications and SAR-ADC. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1048-6 Issue No:Vol. 93, No. 3 (2017)

Authors:Shailesh Singh Chouhan; Kari Halonen Pages: 523 - 529 Abstract: This work presents a current reference circuit fabricated in a standard 0.18 μm CMOS technology. The reference current is obtained by applying thermal compensation voltage in the conventional self-biased or beta multiplier-based current reference circuit. Eight prototypes of the proposed architecture were measured which have resulted into the mean reference current of 26.1 nA with the temperature coefficient of 202.1 ppm/°C. These measurements were performed in the temperature range of − 40 to + 85 °C. The circuit is capable of working over the supply voltage range of 1–2 V with the measured mean line sensitivity of 2.18%/V. The maximum measured power dissipation of the circuit is 104 nW at 2 V. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1057-5 Issue No:Vol. 93, No. 3 (2017)

Authors:D. Anitha; K. Manjunathachari; P. Sathish Kumar; G. Prasad Pages: 531 - 538 Abstract: In this paper, a novel 8 Transistor Static Random Access Memory (SRAM) cell is proposed to reduce the static power introduced by sub threshold and gate leakages, thus reducing the total power dissipation. The power dissipation of the proposed cell in standby mode has reduced considerably, compared to the conventional 6 Transistor SRAM cell and NC SRAM cell. A better stability is achieved in this cell under different process corners. The proposed technique reduces the standby power to 6.22 nW, which is almost negligible compared to that of a 6T SRAM cell (4.23 uW). Hence, the proposed cell is more suitable for standby mode operation. The total power of the proposed cell is reduced by 25.6% and the read-stability is increased by 40% compared to the conventional 6T SRAM cell. Cadence (Virtuoso) tools are used for simulation with gpdk 45-nm process technology. PubDate: 2017-12-01 DOI: 10.1007/s10470-017-1061-9 Issue No:Vol. 93, No. 3 (2017)

Authors:Xu Cheng; Liang Zhang; Xianjin Deng Abstract: This paper presents a high dynamic range programmable gain amplifier (PGA) with linear-in-dB and digital to analog converter (DAC) gain control using a BiCMOS process. The proposed PGA is composed of a folded Gilbert variable gain amplifier cell, a DC offset cancellation circuitry, two inductorless fixed gain amplifiers with bandwidth extension, a symmetrical exponential voltage generator, a novel buffer amplifier with active inductive peaking for testing purposes and a 10 bit R-2R DAC. The linear-in-dB and DAC gain control scheme facilitate the analog baseband gain tuning accuracy and stability, which also provides an efficient way for digital baseband automatic gain control. The PGA chip is fabricated using 0.13 μm SiGe BiCMOS technology. With a power consumption of 80 mA@1.2 V supply voltage, the fabricated circuit exhibits a tunable gain range of − 30–27 dB (DAC linear gain step guaranteed), a 3 dB bandwidth of around 3.5 GHz and a gain resolution of better than 0.07 dB. PubDate: 2017-11-24 DOI: 10.1007/s10470-017-1086-0

Authors:Mojtaba Maleknejad; Reza Faghih Mirzaee; Keivan Navi; Hamid Reza Naji Abstract: This paper presents two new 4:2 compressors based on capacitive multi-threshold threshold logic (MTTG), and Carbon Nanotube Field Effect Transistors (CNFETs). The entire capacitor network is divided into two groups in one of the proposed designs. As a result, the number of voltage levels is reduced and the entire structure becomes less sensitive to Process, Voltage, and Temperature variations in comparison with other similar capacitive Threshold Logic (TL) circuits. All designs are simulated by Synopsys HSPICE and 32 nm CNFET technology in different situations and conditions. Simulation results demonstrate the superiority of the second proposed design. It operates 55.9% faster and consumes about 7.2% less power than the second best TL structure (CSTFA). It also operates 16.2% faster and consumes 13.6% less energy in comparison with a traditional design (BLG). Moreover, estimations show that the first proposed design occupies the least area among the capacitive TL circuits. PubDate: 2017-11-24 DOI: 10.1007/s10470-017-1077-1

Authors:Tzu-Yun Wang; Sheng-Yu Peng; Jennifer Hasler Abstract: This paper presents an impact and low power algorithmic ADC which is implemented on a large scale field programmable analog array chip. The proposed circuit is merely composed of the elements within a single computational analog block (CAB) to minimize the area and parasitic effects. The feedback residue is amplified by a simple operational transconductance amplifier with a gain of \(-\,2\) . Therefore, a new algorithm for the conversion process is proposed for this negative gain structure. Furthermore, owing to the floating-gate technique adopted in this work, the parameters and routes of the ADC achieve exceptional reconfigurability. The offset, reset, reference, threshold voltages, and gain all can be adjusted for optimizing the ADC performance. The measured results of the DNL is + 2/− 1 LSB and the INL is + 1.8/− 1.4 LSB, respectively. Under an 8-bit resolution and a 62.5 Hz sampling frequency condition, the measured effective number of bit is 7.6 bits. The total current consumption of the OTAs and FGOTAs is \(1.6\,\upmu\) A under a 2.5 V supply voltage. Each CAB which includes all components, switches, and routings occupies an area of \(400 \times 500\,{\mathrm{mm}}^2\) . PubDate: 2017-11-23 DOI: 10.1007/s10470-017-1084-2

Authors:Bal Chand Nagar; Sajal K. Paul Abstract: In this paper an analog voltage divider employing a single operational transresistance amplifier as active element is proposed. Its extension as square-rooter and inverse function has also been discussed. The circuit is found to function as a two quadrant divider. The realization of the circuit as a resistorless configuration is also given which eases monolithic integration and consumes less space. The performance of the proposed circuit is verified through PSPICE (Cadence EDA Tools) simulations using 0.25 µm CMOS technology parameters provided by MOSIS (AGILENT). The various simulation results confirm the feasibility of the proposed circuits. PubDate: 2017-11-22 DOI: 10.1007/s10470-017-1085-1

Authors:Kyunghoon Chung; Seong-Kwan Hong; Oh-Kyong Kwon Abstract: In this paper, we propose a fully integrated switched-capacitor (SC) DC–DC converter with hybrid output regulation that allows a predictable switching noise spectrum. The proposed hybrid output regulation method is based on the digital capacitance modulation for fine regulation and the automatic frequency scaling for coarse regulation. The automatic frequency scaler and on-chip current sensor are implemented to adjust the switching frequency at one of the frequencies generated by a binary frequency divider with change in load current. Thus, the switching noise spectrum of the proposed SC DC–DC converter can be predicted over the entire load range. In addition, the bottom-plate losses due to the parasitic capacitances of the flying capacitors and the gate-drive losses due to the gate capacitances of switches are reduced at light load condition since the switching frequency is automatically adjusted. The proposed SC DC–DC converter was implemented in a 0.13 µm CMOS process with 1.5 V devices, and its measurement results show that the peak efficiency and the efficiency at light load condition are 69.2% and higher than 45%, respectively, while maintaining a predictable switching noise spectrum. PubDate: 2017-11-22 DOI: 10.1007/s10470-017-1080-6

Authors:Shaoquan Gao; Hanjun Jiang; Zhaoyang Weng; Yanshu Guo; Jingjing Dong; Fule Li; Zhihua Wang Abstract: The phase-domain analog-to-digital converter (Ph-ADC) is proved to be more power efficient than traditional amplitude ADCs in wireless receivers . A low power multi-step Ph-ADC for zero intermediate frequency (IF) GFSK receivers as defined in Bluetooth low energy protocol is proposed in this paper. With dedicatedly designed binary code scheme and multi-step operation, the Ph-ADC requires only 52 current elements and one comparator, in contrast to the design in literature using 260 current elements and 8 comparators. Non-idealities due to transconductance errors and offset errors are theoretically analyzed, followed by a design strategy to minimize trip point errors. Simulation results show that the digital intensive Ph-ADC consumes only 7.9 μA current from a 1.8 V supply when implemented in a 180 nm CMOS process. Monte-Carlo simulations show that the maximum trip point error is only 2.3°, which is less than 1/8 least significant bit. When the Ph-ADC is used in a GFSK demodulator, the required IF Eb/N0 is 13.5 dB to achieve a bit error rates of 0.1%. PubDate: 2017-11-22 DOI: 10.1007/s10470-017-1081-5

Authors:Sudip Kundu; Pradip Mandal Abstract: In this paper, an efficient deterministic methodology for generating Pareto-optimal front (PoF) of analog circuits is proposed. The proposed methodology utilizes modified epsilon constraint method along with geometric programming based circuit sizer to determine the Pareto-optimal points (PoPs) of the analog circuits. The generated PoPs are then modeled to generate the PoFs. The efficiency of the proposed methodology and the accuracy of the generated PoF has been verified with respect to that of the commonly used stochastic approach. It is found that to generate PoF having similar spread, the proposed methodology takes only 20 min whereas the stochastic approach takes 60 h. It also has been observed that the accuracy of the generated PoF using the proposed methodology improved by more than 10% with respect to that of the stochastic approach. The proposed methodology has been implemented to generate the PoF of a two-stage Op-Amp, fully differential folded cascode Op-Amp, fully differential single-stage and two-stage Op-Amps. The generated PoFs have been utilized for (1) feasibility checking for a user given specification of an Op-Amp, (2) performance prediction and (3) topology selection of the analog circuit. As per authors’ knowledge, this is the first paper which deals with all the aspects, i.e., generation, modeling and application of the PoF of the analog circuits. PubDate: 2017-11-21 DOI: 10.1007/s10470-017-1073-5

Authors:Imen Ghorbel; Fayrouz Haddad; Wenceslas Rahajandraibe; Mourad Loulou Abstract: The original publication of the article contains an error in the author Dr. Loulou’s biography. The correct version of the biography is given below. PubDate: 2017-10-25 DOI: 10.1007/s10470-017-1068-2