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To achieve low power consumption and high performance, an approximate multiplier is a commonly used operation. A new approximate computation method has been used for Error Tolerant Image Processing applications. This operation is popular in error tolerance applications. Inexact computing is applied to error-tolerant digital signal processing applications where error can be tolerated. Multiplier is the basic unit of arithmetic logic unit of any computer computational unit. In this paper, a new approximate compressor computation method is proposed for error-tolerant image processing applications. An approximate compressor has been designed for better output power with an improved figure of merit. A comparison of the proposed compressor with the previous 4:2 compressor design has been investigated and a reduction in area, delay and power consumption has been achieved. A similar algorithm has been applied to 8-bit multiplier applications which have considerable error performance. With the newly designed multiplier using a compressor, the simulation results compared the best power utilization. The results of designing the multiplier indicate that the proposed design of a multiplier using an approximate compressor achieves a reduction in power by 129 mw. [ABSTRACT FROM AUTHOR]

Frequency-modulated continuous-wave (FMCW) signals-based radar systems can outrun the optical and ultrasound sensors in dark and severe weather conditions. FMCW radar systems require a fast settling frequency synthesizer to reduce the chirp signal's inactive and modulation times. This work proposes a new C-B and FMCW Transmitter based on Fast Settling Fractional-N DPLL (FS-FNDPLL) and ring-based pulse injection locking oscillator (R-PILO). The proposed FS-FNDPLL generates an ultra-fast low-noise smooth narrowband chirp by introducing an automatic controller-based TDC switching (AC-TDCSw) scheme in the forward loop of FNDPLL. Also, the proposed FS-FNDPLL employs a new background gain calibrated digital-to-time converter (BGC-DTC) as a fractional divider in the feedback path for the quantization noise cancellation (QNC). The proposed FMCW transmitter uses an R-PILO to produce fast switching adjacent carriers after generating a narrowband chirp using FS-FNDPLL. The main features of the proposed FMCW to accelerate settling time with AC-TDCSw, BGC-DTC and the integration of spur suppressing pulse generator (SSPG) in R-PILO enable ultra-fast chirps with less phase noise and spur levels. The proposed transmitter up-converts the 500 MHz narrowband chirp signal onto four adjacent carriers for obtaining a 2 GHz chirp at the C-band. The simulation results prove that the proposed FMCW Transmitter consumes 79 mW power. Furthermore, the phase noise of the proposed FS-FNDPLL is reduced to − 1 1 3 dBc/Hz at 1 MHz. The proposed FS-FNDPLL reduces the settling time to 1 μ s with the introduced AC-TDCSw scheme. [ABSTRACT FROM AUTHOR]

Improved speed, reduced delay, reduced size and reduced power are the most important requirements of integrated circuits. The carry select adder (CSA) is one of the most important adders in most data processors for performing arithmetic operations. The speed of parallel adders can be enhanced CSA, which widens the area to speed and eliminates propagation delays. The major problem faced in CSA is inefficient area due to the usage of multiple pairs of Ripple carry adders (RCAs) for generating the sums and carry. This research paper proposes the modified 32-bit square root carry select adder (MSCSLA) to improve the direct digital synthesizer's performance (DDS). DDS plays an effective role in the digital system due to its ability of broad frequency generation. Phase accumulator is the main component in the DDS synthesizer, where the speed of the adder is enhanced through MSCSLA. The general square root CSA still consumes more power due to the assembly of more RCAs. Hence, in the proposed approach, certain sets of RCAs are replaced with BEC1 (Binary to excess 1 convertor) to improve the speed and reduce the delay of the adder. Finally, the continuous sinusoidal waveform is attained by attenuating the high-frequency components by adopting a low pass filter. The entire structure of DDS is designed using Xilinx Verilog coding. The Simulation result shows better outcomes in terms of area, delay, power, and high performance in the DDS synthesizer compared to the existing CSAs. When compared to the existing adders, the area occupied by the proposed MSCSLA model is attained to be 636 μ m2, the power is achieved as 50.125 μ W and delay is attained to be 1.280 ns, which are comparatively less. When comparing delay and maximum frequency with the existing techniques, the proposed model obtained minimum delay and maximum frequency. The overall power consumption by the proposed model is also attained to be lower than the existing techniques. [ABSTRACT FROM AUTHOR]

MEMS-based piezoelectric vibration energy harvesters found suitable to power wireless sensor nodes, typically in a remote area of operation. In MEMS technology, piezoelectric type vibration energy harvesters are realized using fixed-fixed or fixed-free cantilever structures. These structures are spring mass damper systems that have a fixed resonance frequency which is to be matched with ambient vibration frequency. The low resonance frequency of the cantilever gives better output with the low-frequency mechanical vibrations. Parameters such as width, length and thickness must be critically controlled to achieve low-frequency response during device fabrication. This paper presents the optimized fabrication process for guided two-beam type piezoelectric vibration energy harvester device. The device thickness is critically controlled using tetramethylammonium hydroxide zig during wet bulk micromachining followed by beam thinning process using deep reactive ion etching on the back side of the silicon wafer. A highly c-axis oriented zinc oxide layer of 2.5 µm thickness is sandwiched between aluminum electrodes on the front side of the silicon wafer for harvesting electric potential. The laser Doppler vibrometer test gives the resonance frequency of the fabricated device around 466 Hz which is lowest reported so far for the guided two-beam device. The resonance frequency of the device reported has been reduced by 32.85% than the earlier reported guided two-beam device. The device when vibration shaker tested was found to be operational in the very low-frequency range up to 10 Hz giving a sensitivity of 1.648 mV/m/s2 near resonance frequency. [ABSTRACT FROM AUTHOR]

This paper reports the fabrication of MEMS-based guided two-beam piezoelectric energy harvester for low-frequency operation. A highly c-axis-oriented zinc oxide thin film of 2.5- $\mu \text{m}$ thickness covered with 0.5- $\mu \text{m}$ plasma-enhanced chemical vapor deposition SiO2 is sandwiched between the aluminum electrodes to form split electrodes on the two beams. A pyramidal-shaped seismic mass that gives a higher electric potential is realized by bulk micromachining using CMOS compatible 25 wt% tetramethyl ammonium hydroxide wet etching. The thickness of the beams is optimized using deep reactive-ion etching to achieve a low-frequency operation. COMSOL Multiphysics has been used to study the stress distribution to optimize the dimension and placement of the split electrodes. The optimized split electrodes give a reduced resonance frequency by 4.2% when compared with previously used electrode pattern ensuring maximum electric potential generation for guided two-beam structure. The resonance frequency of the device measured experimentally using laser Doppler vibrometer comes to be 466 Hz. The packaged device exhibits a maximum sensitivity of 1.5089 mV/m/s2 in the frequency range from 160 to 1000 Hz. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvesters are gaining importance due to simplicity in design, operation and ability to power microelectronic sensor nodes in remote areas. A cantilever based piezoelectric energy harvester acts as a spring mass damper system having a resonance frequency tuned with ambient vibrations of low frequency. Maximum potential is generated when the resonance frequency of the energy harvester matches with frequency of ambient vibration. The highlight of this paper is a pyramidal shape seismic mass which results in a higher generated potential as compared to the square shaped seismic mass. This pyramidal shape is realized using tetra methyl ammonium hydroxide CMOS compatible 25 wt% wet etching. Two beam and four beam structures are front released using deep reactive ion etching which are fixed from both ends and having pyramidal shape seismic mass at the center. This paper presents a comparison of guided four beam and two beam cantilever type piezoelectric energy harvester fabricated using MEMS technology using a laser doppler vibrometer (LDV). Experimentally using LDV the resonance frequency for the fabricated guided two beam cantilever structure resonance frequency is 1971.9 Hz and for the guided four beam cantilever structure is 2540.6 Hz. Bandwidth for two beam cantilever structure is 40.6 Hz whereas for four beam cantilever structure bandwidth comes as 101.9 Hz. The maximum displacement measured for two beam cantilever structure at resonance frequency is 49.67 nm and for four beam cantilever structure maximum displacement is 32.17 nm. FEM (Finite Element Method) analysis for the guided two beam and guided four beam device is also performed and parameters such as resonance frequency, displacement, electric potential and von Mises stress are also reported and compared in this paper. Further the resonance frequency calculated analytically and the results obtained from FEM simulator and experimental results are also compared and it is found that they are in close agreement with each other. [ABSTRACT FROM AUTHOR]

MEMS devices have found applicability in remote area of operation such as temperature monitoring in extreme climates, structural health monitoring, and car tire pressure monitors etc. due to compact shape and ability to operate in low power (few microwatts). These devices are generally powered through a small battery but replacement at such remote locations is not feasible which imposes a serious challenge of powering these devices for infinitely long time. Energy harvesting provides an unending power source (few milli-watts) which is adequate to power these MEMS devices having remote area applications. Piezoelectric type energy harvesters are the most promising and efficient vibration energy harvesters that are widely used. Increased depth of cavity due to large displacement, residual stress and lower output potential are demerits of single cantilever type piezoelectric energy harvester. In this paper a new design of guided four beam cantilever type piezoelectric energy harvester is simulated, analyzed and reported. Displacement of 0.095 µm is achieved at an input acceleration of 1 g (9.8 m/s) which is 32.14 % less than displacement of single beam cantilever which has also been reported and compared with the new proposed design in this paper. Maximum stress calculated at an input acceleration of 5 g is 4.7 × 10 N/m on piezoelectric layer and 8 × 10 N/m on guided beams which is well below the fracture stress for silicon. Tensile and compressive stress generates potential of opposite polarities that can be harvested using separate set of capacitors. Potential generated ranges from 17.84 to 89.21 mV for input acceleration ranging from 1 to 5 g respectively. [ABSTRACT FROM AUTHOR]