Abstract
In the present research, thermoplastic polyurethane/polypyrrole (TPU/PPy) dielectric composites film and the lightweight foamyfilm are fabricated using the most simplified solvent casting ...and modified phase separation water immersion techniques, respectively. The establishment of chemical interaction and morphological investigations of the fabricated systems are analyzed by Raman spectroscopy and field emission scanning electron microscope (FESEM), respectively. Various dielectric properties, together with complex impedance, are determined over a wide range of frequencies (1 Hz–1 MHz) and temperatures (25°C–120°C). Most interestingly, above 30 Hz frequency, a significantly low value (<0.1) dielectric loss tangent (tan
δ
) is obtained at ambient temperature. A 90:10 foamyfilm exhibits a dielectric permittivity (
ε
') and tan
δ
of 236 and 0.05 at 50 Hz frequency, respectively. Both 90:10 film and foamyfilm systems exhibit a significantly increasing trend of
ε
′ as well as low tan
δ
with an increase in temperature over a wide range of frequencies. The thermogravimetric analysis (TGA) results of the 90:10 film and foamyfilm indicate the superior thermal stability of the 90:10 foamyfilm system. Based on the obtained low dielectric loss, the fabricated dielectric film, and foamyfilm can be employed in energy storage and high‐temperature sensing applications.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Voltage-controlled oscillator (VCO)-based analog-to-digital converter (ADC) have been used for the direct digitization of sensor signals. This article proposes a Johnson counter (JC) based multiphase ...generation for VCO-based ADC for direct digitization of low amplitude sensor signals. The proposed approach reduces the flicker noise of the VCO, thereby giving better signal-to-noise (SNR) ratio. A prototype design is implemented at a printed circuit board (PCB) level using discrete components achieving a signal-to noise + distortion ratio (SNDR) SNDR of 59.2 dB over a 5 kHz bandwidth for <inline-formula> <tex-math notation="LaTeX">200 \text {mV}_{\text {pp},\text {diff}} </tex-math></inline-formula> input signal using an eight-phase JC-based VCO ADC sampled at 2.5 MHz. The proposed design also achieves a dynamic range of 64 dB for 5-kHz bandwidth and is therefore ideal for many sensor interface applications.
This letter presents a technique that facilitates high speed analog-to-digital conversion based on the multi-channel sampling of analog signals using the concept of Generalized Sampling and based on ...pure delay analog front-end filters and i-taps digital FIR reconstruction filter for the ith-channel. The digital FIR reconstruction filters are chosen in a manner that a closed form expression of the front-end analog filters can be obtained by inverting a Vandermonde matrix whose inverse can be written as a product U-1L-1 of two triangular matrices, viz. upper triangular matrix U and lower triangular matrix L.
Fabrication of polymer nanocomposites with excellent dielectric properties in an environmentally friendly approach is a challenging job. Nanocomposites based on polyvinyl alcohol (PVA) and graphene ...oxide (GO) are fabricated using deionized water by solvent casting technique. The agglomerations, intercalation, and exfoliation pattern of dispersion of GO phase in the interface are observed in HRTEM and FESEM photomicrographs.1‐Allyl‐3‐methyl imidazolium chloride (AMIC) as ionic liquid (IL) is incorporated for better dispersion and compatibility. The Fourier‐transform infrared (FTIR) and Raman analysis confirms the establishment of hydrogen bonding and cation‐π interaction between AMIC and GO platelets. The enhancement of the tensile results up to 2 wt% of GO loading ensures the reinforcing nature of GO. Further increase in tensile strength in IL contend systems ensure the bridging activity, which facilitates the stress transfer at the interface. The effect of GO loading, IL, and temperature on the dielectric properties, such as dielectric permittivity (ε′), AC conductivity (σac), impedance (Z′ and Z″), and Nyquist plot are explored. The significant enhancement in ε′ with the incorporation of GO loading level and IL in an external electric field is mostly due to the increase in polarizable dipoles and migration of electric charge carriers, which result the accumulation of charge particles with different relaxation time at the interface. The interfacial polarization phenomena become more frequent at higher temperature, which again results increase in ε′. A remarkable increase in σac and reduction of Z′ and Z″ of the fabricated PVA/GO systems with an increase in GO loading level ensures the pronounced tunneling and hopping phenomenon at the interface. The diminished area obtained under the Nyquist plots with increase in GO loading level and temperature ensures about the decrease in bulk resistivity (RB) and increase in charge storing ability of the developed systems. The significant improvement in dielectric properties at higher temperature reveals the negative temperature coefficient behavior of resistance (NTC) of the developed systems.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The electron beam (EB) crosslinked and MWCNT reinforced ethylene acrylic elastomer (AEM) nanocomposites have been developed with varying the EB dose (50–250 kGy) and MWCNT loading level (0–8 parts ...per hundred gram of rubber (phr)) for various applications. The crosslink density and gel fraction significantly increase with increase in EB dose and MWCNT loading which ensures the radiation sensitizing effects of MWCNT. The chain scission to crosslink density has been check by using Flory–Rehner relationship at room temperature and the decrease in slope of the plots again confirms the predominance of crosslinking over chain scission at higher EB dose. The dispersion patterns of the MWCNT phase in bulk AEM matrix have been analyzed by using FESEM technique. Uniformly dispersed MWCNT with closely spaced network structures has been found in the FESEM photomicrographs at 4 phr loading level. The tensile strength and tensile modulus are extensively increased with increasing EB dose and up to 6 phr of MWCNT loading which ensures the reinforcing nature of MWCNT. Increase in tensile modulus (M100) and storage modulus (E ') with increase in EB dose and MWCNT indicates the absorption of applied load due to decrease in free volume of the systems. Increase in decomposition temperature with MWCNT loading of the nanocomposites has been confirmed from the thermal analysis. The significant increase in dielectric permittivity (εʹ) on increasing the MWCNT loading is mostly due to the increase accumulation of charge particles at the interface as well as increase in polarizable dipoles. The improvement in AC conductivity (σac) of these nanocomposites is mostly due to the easy electron tunnelling and hopping transport processes executed through the constructed networks by MWCNT in the bulk as well as interface.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Successive-approximation register (SAR) ADCs are susceptible to non-linearities due to capacitor mismatch. This brief proposes a transition points-based calibration of the SAR ADC using an ...RC-filtered square wave by looking at the histogram of output digital codes to improve the linearity without any additional analog circuitry. The proposed method is validated with an <inline-formula> <tex-math notation="LaTeX">\mathbf {8} </tex-math></inline-formula>-bit SAR ADC fabricated in UMC <inline-formula> <tex-math notation="LaTeX">\mathbf {180} </tex-math></inline-formula>-nm CMOS. The proposed calibration algorithm improves the signal-to-noise and distortion ratio (SNDR) of the <inline-formula> <tex-math notation="LaTeX">\mathbf {8} </tex-math></inline-formula>-bit ADC from <inline-formula> <tex-math notation="LaTeX">\mathbf {42.87} </tex-math></inline-formula> dB to <inline-formula> <tex-math notation="LaTeX">\mathbf {46.91} </tex-math></inline-formula> dB, and the spurious-free dynamic range (SFDR) from <inline-formula> <tex-math notation="LaTeX">\mathbf {51.95} </tex-math></inline-formula> dB to <inline-formula> <tex-math notation="LaTeX">\mathbf {60.61} </tex-math></inline-formula> dB.
Convolutional neural networks (CNNs) have performed exceptionally well on a variety of image classification tasks but need significant amount of memory and computational resources. In this brief, we ...propose a power-of-2 weights based CNN inference engine, that takes images whose pixels are either binarized or quantized to low-resolution and also has its weights at each layer reduced to powers-of-2, thus replacing the multiplication operations with a simple shift operation, thereby reducing the computations significantly. The proposed CNN architecture, designed to be used in an always-on inference engine, has been demonstrated for SVHN and CIFAR-10 datasets and achieves an accuracy of 83.23% and 87.02%, respectively, while using 3-bit quantized images. The proposed architecture, therefore, achieves a performance comparable to inference engines that used 8-bit quantized images while achieving a frame-rate of 380 FPS by consuming 0.789 W of dynamic power, a very competitive energy efficiency of 892.45 GOPs/J. The system requires ≈1 Mb of memory for storing weights, making it suitable for memory constrained edge devices and ASIC implementations.
The performance of a time-interleaved analog-to-digital converter (TI-ADC) gets compromised due to offset , gain mismatch , timing mismatch , and bandwidth mismatch . This article analyzes a TI-ADC ...from a generalized sampling perspective and then develops closed-form expression of the signal-to-noise and distortion ratio (SNDR) of an <inline-formula> <tex-math notation="LaTeX">N </tex-math></inline-formula>-channel TI-ADC when all of gain mismatch , timing mismatch , and bandwidth mismatch are present at the same time. The analysis is then extended to incorporate the effect of offset along with the other three mismatches to arrive at closed-form expression of SNDR in the presence of all the mismatches. The closed-form expressions have been validated through numerical simulations as well.
This brief presents an energy efficient wideband low noise amplifier (LNA) operating in subthreshold regime. Wideband matching and low noise figure in subthreshold domain is achieved by using a gate ...inductor-assisted impedance matching and a current reuse feed-forward noise cancelation technique, respectively. Fabricated in UMC 0.18-<inline-formula> <tex-math notation="LaTeX"> {\mu }\text{m} </tex-math></inline-formula> CMOS technology, the proposed LNA draws 1 mA from 1.8-V supply and achieves a voltage gain of 13 dB (taking into account a 8 dB loss in buffer), minimum noise figure (<inline-formula> <tex-math notation="LaTeX">{\text {NF}}_{\text {min}} </tex-math></inline-formula>) of 6 dB, and 3 dB bandwidth from 2 to 5 GHz.
