5 research outputs found
LOW POWER AND HIGH SIGNAL TO NOISE RATIO BIO-MEDICAL AFE DESIGN TECHNIQUES
The research work described in this thesis was focused on finding novel techniques to
implement a low-power and noise Bio-Medical Analog Front End (BMEF) circuit
technique to enable high-quality Electrocardiography (ECG) sensing. Usually, an ECG
signal and several bio-medical signals are sensed from the human body through a pair
of electrodes. The electrical characteristics of the very small amplitude (1u-10mV)
signals are corrupted by random noise and have a significant dc offset. 50/60Hz power
supply coupling noise is one of the biggest cross-talk signals compared to the thermally
generated random noise. These signals are even AFE composed of an Instrumentation
Amplifier (IA), which will have a better Common Mode rejection ratio (CMRR). The main
function of the AFE is to convert the weak electrical Signal into large signals whose
amplitude is large enough for an Analog Digital Converter (ADC) to detect without having
any errors. A Variable Gain Amplifier (VGA) is sometimes required to adjust signal
amplitude to maintain the dynamic range of the ADC. Also, the Bio-medical transceiver
needs an accurate and temperature-independent reference voltage and current for the
ADC, commonly known as Bandgap Reference Circuit (BGR). These circuits need to
consume as low power as possible to enable these circuits to be powered from the
battery.
The work started with analysing the existing circuit techniques for the circuits
mentioned above and finding the key important improvements required to reach the
target specifications. Previously proposed IA is generated based on voltage mode signal
processing. To improve the CMRR (119dB), we proposed a current mode-based IA with
an embedded DC cancellation technique. State-of-the-art VGA circuits were built based
on the degeneration principle of the differential pair, which will enable the variable gain
purpose, but none of these techniques discussed linearity improvement, which is very
important in modern CMOS technologies. This work enhances the total Harmonic
distortion (THD) by 21dB in the worst case by exploiting the feedback techniques around
the differential pair. Also, this work proposes a low power curvature compensated
bandgap with 2ppm/0C temperature sensitivity while consuming 12.5uW power from a
1.2V dc power supply. All circuits were built in 45nm TSMC-CMOS technology and
simulated with all the performance metrics with Cadence (spectre) simulator. The circuit
layout was carried out to study post-layout parasitic effect sensitivity
Advances in Solid State Circuit Technologies
This book brings together contributions from experts in the fields to describe the current status of important topics in solid-state circuit technologies. It consists of 20 chapters which are grouped under the following categories: general information, circuits and devices, materials, and characterization techniques. These chapters have been written by renowned experts in the respective fields making this book valuable to the integrated circuits and materials science communities. It is intended for a diverse readership including electrical engineers and material scientists in the industry and academic institutions. Readers will be able to familiarize themselves with the latest technologies in the various fields
Linear Operation of Switch-Mode Outphasing Power Amplifiers
Radio transceivers are playing an increasingly important role in modern society. The
”connected” lifestyle has been enabled by modern wireless communications. The demand
that has been placed on current wireless and cellular infrastructure requires increased spectral
efficiency however this has come at the cost of power efficiency. This work investigates
methods of improving wireless transceiver efficiency by enabling more efficient power
amplifier architectures, specifically examining the role of switch-mode power amplifiers in
macro cell scenarios. Our research focuses on the mechanisms within outphasing power
amplifiers which prevent linear amplification. From the analysis it was clear that high power
non-linear effects are correctable with currently available techniques however non-linear effects
around the zero crossing point are not. As a result signal processing techniques for suppressing
and avoiding non-linear operation in low power regions are explored. A novel method of digital
pre-distortion is presented, and conventional techniques for linearisation are adapted for the
particular needs of the outphasing power amplifier. More unconventional signal processing
techniques are presented to aid linearisation of the outphasing power amplifier, both zero
crossing and bandwidth expansion reduction methods are designed to avoid operation in nonlinear
regions of the amplifiers. In combination with digital pre-distortion the techniques
will improve linearisation efforts on outphasing systems with dynamic range and bandwidth
constraints respectively.
Our collaboration with NXP provided access to a digital outphasing power amplifier,
enabling empirical analysis of non-linear behaviour and comparative analysis of behavioural
modelling and linearisation efforts. The collaboration resulted in a bench mark for linear
wideband operation of a digital outphasing power amplifier. The complimentary linearisation
techniques, bandwidth expansion reduction and zero crossing reduction have been evaluated in
both simulated and practical outphasing test benches. Initial results are promising and indicate
that the benefits they provide are not limited to the outphasing amplifier architecture alone.
Overall this thesis presents innovative analysis of the distortion mechanisms of the
outphasing power amplifier, highlighting the sensitivity of the system to environmental effects.
Practical and novel linearisation techniques are presented, with a focus on enabling wide band
operation for modern communications standards
Shortest Route at Dynamic Location with Node Combination-Dijkstra Algorithm
Abstract— Online transportation has become a basic
requirement of the general public in support of all activities to go
to work, school or vacation to the sights. Public transportation
services compete to provide the best service so that consumers
feel comfortable using the services offered, so that all activities
are noticed, one of them is the search for the shortest route in
picking the buyer or delivering to the destination. Node
Combination method can minimize memory usage and this
methode is more optimal when compared to A* and Ant Colony
in the shortest route search like Dijkstra algorithm, but can’t
store the history node that has been passed. Therefore, using
node combination algorithm is very good in searching the
shortest distance is not the shortest route. This paper is
structured to modify the node combination algorithm to solve the
problem of finding the shortest route at the dynamic location
obtained from the transport fleet by displaying the nodes that
have the shortest distance and will be implemented in the
geographic information system in the form of map to facilitate
the use of the system.
Keywords— Shortest Path, Algorithm Dijkstra, Node
Combination, Dynamic Location (key words