ASIC Design of Radix-2, 8-point FFT Processor

In split radix architecture, large sizes Fast Fourier Transforms (FFT) are decomposed into small independent computations to reduce storage burden. Radix-2, 8 point is one the popular choice in split radix for small independent computation. Author proposes the FFT processor architecture for this small independent computation i.e. radix-2, 8-point FFT. This paper brief architecture comprising Butterfly Unit (BU), register set and controller. The novelty of this architecture is that it replaces the series of Processing Elements (PE) by single BU. BU computes two halves of the computations concurrently. Arithmetic computations are performed in floating point form to overcome the nonlinearities. All computations are controlled by tailored instruction set. All instructions are of same size and have same execution time. Twiddle constants are implicitly available in the instruction. Internal computations are stored in register set to avoid the load and store operations with memory. The mean square error of the computation is reduced by 41.95 % and 55.76 % in magnitude and phase respectively as compared with computations performed by rounding the twiddle constant. This FFT processor is synthesized, placed and routed for 45 nm technology of nangate open cell library. The BU of this architecture is 18 % smaller and 5 % faster as compared with smallest and fastest BU reported previously. The hardware cost metric i.e.    Dp mm2 ns2 mW = 1.37 of proposed processor and 32.51 % less as compared with the previous work

Analog and Mixed Signal Design towards a Miniaturized Sleep Apnea Monitoring Device

Sleep apnea is a sleep-induced breathing disorder with symptoms of momentary and often repetitive cessations in breathing rhythm or sustained reductions in breathing amplitude. The phenomenon is known to occur with varying degrees of severity in literally millions of people around the world and cause a range of chronicle health issues. In spite of its high prevalence and serious consequences, nearly 80% of people with sleep apnea condition remain undiagnosed. The current standard diagnosis technique, termed polysomnography or PSG, requires the patient to schedule and undergo a complex full-night sleep study in a specially-equipped sleep lab. Due to both high cost and substantial inconvenience, millions of apnea patients are still undiagnosed and thus untreated. This research work aims at a simple, reliable, and miniaturized solution for in-home sleep apnea diagnosis purposes. The proposed solution bears high-level integration and minimal interference with sleeping patients, allowing them to monitor their apnea conditions at the comfort of their homes. Based on a MEMS sensor and an effective apnea detection algorithm, a low-cost single-channel apnea screening solution is proposed. A custom designed IC chip implements the apnea detection algorithm using time-domain signal processing techniques. The chip performs autonomous apnea detection and scoring based on the patient’s airflow signals detected by the MEMS sensor. Variable sensitivity is enabled to accommodate different breathing signal amplitudes. The IC chip was fabricated in standard 0.5-μm CMOS technology. A prototype device was designed and assembled including a MEMS sensor, the apnea detection IC chip, a PSoC platform, and wireless transceiver for data transmission. The prototype device demonstrates a valuable screening solution with great potential to reach the broader public with undiagnosed apnea conditions. In a battery-operated miniaturized medical device, an energy-efficient analog-to-digital converter is an integral part linking the analog world of biomedical signals and the digital domain with powerful signal processing capabilities. This dissertation includes the detailed design of a successive approximation register (SAR) ADC for ultra-low power applications. The ADC adopts an asynchronous 2b/step scheme that halves both conversion time and DAC/digital circuit’s switching activities to reduce static and dynamic energy consumption. A low-power sleep mode is engaged at the end of all conversion steps during each clock period. The technical contributions of this ADC design include an innovative 2b/step reference scheme based on a hybrid R-2R/C-3C DAC, an interpolation-assisted time-domain 2b comparison scheme, and a TDC with dual-edge-comparison mechanism. The prototype ADC was fabricated in 0.18μm CMOS process with an active area of 0.103 mm^(2), and achieves an ENoB of 9.2 bits and an FoM of 6.7 fJ/conversion-step at 100-kS/s

Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development