80 research outputs found
High-efficiency high voltage hybrid charge pump design with an improved chip area
A hybrid charge pump was developed in a 0.13- Bipolar-CMOS-DMOS (BCD) process which utilised high drain-source voltage MOS devices and low-voltage integrated metal-insulator-metal (MIM) capacitors. The design consisted of a zero-reversion loss cross-coupled stage and a new self-biased serial-parallel charge pump design. The latter has been shown to have an area reduction of 60% in comparison to a Schottky diode-based Dickson charge pump operating at the same frequency. Post-layout simulations were carried out which demonstrated a peak efficiency of 38% at the output voltage of 18.5 V; the maximum specified output voltage of 27 V was also achieved. A standalone serial-parallel charge pump was shown to have a better transient response and a flatter efficiency curve; these are preferable for time-sensitive applications with a requirement of a broader range of output currents. These findings have significant implications for reducing the total area of implantable high-voltage devices without sacrificing charge pump efficiency or maximum output voltage
Analysis of Passive Charge Balancing for Safe Current-Mode Neural Stimulation
Charge balancing has been often considered as one
of the most critical requirement for neural stimulation circuits.
Over the years several solutions have been proposed to precisely
balance the charge transferred to the tissue during anodic and
cathodic phases. Elaborate dynamic current sources/sinks with
improved matching, and feedback loops have been proposed with
a penalty on circuit complexity, area or power consumption.
Here we review the dominant assumptions in safe stimulation
protocols, and derive mathematical models to determine the
effectiveness of passive charge balancing in a typical application
scenario
Role of ICT Innovation in Perpetuating the Myth of Techno-Solutionism
Innovation in Information and Communication Technology has become one of the
key economic drivers of our technology dependent world. In popular notion, the
tech industry or how ICT is often known has become synonymous to all
technologies that drive modernity. Digital technologies have become so
pervasive that it is hard to imagine new technology developments that are not
totally or partially influenced by ICT innovations. Furthermore, the pace of
innovation in ICT sector over the last few decades has been unprecedented in
human history. In this paper we argue that, not only ICT had a tremendous
impact on the way we communicate and produce but this innovation paradigm has
crucially shaped collective expectations and imagination about what technology
more broadly can actually deliver. These expectations have often crystalised
into a widespread acceptance, among general public and policy makers, of
technosolutionism. This is a belief that technology not restricted to ICT alone
can solve all problems humanity is facing from poverty and inequality to
ecosystem loss and climate change. In this paper we show the many impacts of
relentless ICT innovation. The spectacular advances in this sector, coupled
with corporate power that benefits from them have facilitated the uptake by
governments and industries of an uncritical narrative of techno-optimist that
neglects the complexity of the wicked problems that affect the present and
future of humanity
Use of a 3-D Wireless Power Transfer Technique as a Method for Capsule Localization
Capsule endoscopy has been heralded as a technological milestone in the diagnosis and therapeutics of gastrointestinal (GI) pathologies. The location and position of the capsule within the GI tract are important information for subsequent surgical intervention or local drug delivery. Accurate information of capsule location is therefore required during endoscopy. Although radio frequency (RF)-based, magnetic tracking and video localization have been investigated in the past, the complexity of those systems and potential inaccuracy in the localization data necessitate the scope for further research. This article proposes the dual use of a wireless power transfer (WPT) configuration as a method to enable the determination of the location of an endoscopic capsule. Measurements conducted on a homogeneous agar-based liquid phantom predict a maximum error of 12% between the calculated and measured trajectories of the capsule in a working volume of 100 mm mm mm
Communication channel analysis and real time compressed sensing for high density neural recording devices
Next generation neural recording and Brain-
Machine Interface (BMI) devices call for high density or distributed
systems with more than 1000 recording sites. As the
recording site density grows, the device generates data on the
scale of several hundred megabits per second (Mbps). Transmitting
such large amounts of data induces significant power
consumption and heat dissipation for the implanted electronics.
Facing these constraints, efficient on-chip compression techniques
become essential to the reduction of implanted systems power
consumption. This paper analyzes the communication channel
constraints for high density neural recording devices. This paper
then quantifies the improvement on communication channel
using efficient on-chip compression methods. Finally, This paper
describes a Compressed Sensing (CS) based system that can
reduce the data rate by > 10x times while using power on
the order of a few hundred nW per recording channel
Low Noise and High Photodetection Probability SPAD in 180 nm Standard CMOS Technology
A square shaped, low noise and high photo-response single photon avalanche diode suitable for circuit integration, implemented in a standard CMOS 180 nm high voltage technology, is presented. In this work, a p+ to shallow n-well junction was engineered with a very smooth electric field profile guard ring to attain a photo detection probability peak higher than 50% with a median dark count rate lower than 2 Hz/μm2 when operated at an excess bias of 4 V. The reported timing jitter full width at half maximum is below 300 ps for 640 nm laser pulses
Single photon kilohertz frame rate imaging of neural activity
Establishing the biological basis of cognition and its disorders will require high precision spatiotemporal measurements of neural activity. Recently developed genetically encoded voltage indicators (GEVIs) report both spiking and subthreshold activity of identified neurons. However, maximally capitalizing on the potential of GEVIs will require imaging at millisecond time scales, which remains challenging with standard camera systems. Here, application of single photon avalanche diode (SPAD) sensors is reported to image neural activity at kilohertz frame rates. SPADs are electronic devices that when activated by a single photon cause an avalanche of electrons and a large electric current. An array of SPAD sensors is used to image individual neurons expressing the GEVI Voltron‐JF525‐HTL. It is shown that subthreshold and spiking activity can be resolved with shot noise limited signals at frame rates of up to 10 kHz. SPAD imaging is able to reveal millisecond scale synchronization of neural activity in an ex vivo seizure model. SPAD sensors may have widespread applications for investigation of millisecond timescale neural dynamics
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