24 research outputs found
CMOS analog-digital circuit components for low power applications
Dissertação de mestrado em Micro and NanoelectronicsThis dissertation presents a study in the area of mixed analog/digital CMOS power extraction
circuits for energy harvester.
The main contribution of this work is the realization of low power consumption and
high efficient circuit components employable in a management circuit for piezoelectricbased
energy harvester. This thesis focuses on the development of current references and
operational amplifiers addressing low power demands. A brief literature review is conducted
on the components necessary for the power extraction circuit, including introduction to
CMOS technology design and research of known low power circuits. It is presented with
multiple implementations for voltage and current references, as well for operational amplifier
designs.
A self-biased current reference, capable of driving the remaining harvesting circuit, is
designed and verified. A novel operational amplifier is proposed by the use of a minimum
current selector circuit topology. It is a three-stage amplifier with an AB class output stage,
comprised by a translinear circuit. The circuit is designed, taking into consideration noise
reduction. The circuit components are designed based on the 0.35mm CMOS technology.
A physical layout is developed for fabrication purposes. This technology was chosen with
consideration of robustness, costliness and performance. The current reference is capable of
outputting a stable 12nA current, which may remain stable in a broad range of power supply
voltages with a minimum voltage of 1.6V. The operational amplifier operates correctly at
voltages as low as 1.5V. The amplifier power consumption is extremely low, around 8mW,
with an optimal quiescent current and minimum current preservation in the output stage.A principal contribuição desta dissertação é a implementação de circuitos integrados de
muito baixo consumo e alta eficiência, prontos a ser implementados num circuito de extração
de energia com base num elemento piezoelétrico.
Esta tese foca-se no desenvolvimento de um circuito de referência de corrente e um
amplificador operacional com baixa exigência de consumo. Uma revisão da literatura
é realizada, incluindo introdução à tecnologia Complementary Metal-Oxide-Semiconductor
(CMOS), e implementação de conhecidos circuitos de baixo consumo. Várias implementações
de referência de tensão e corrente são consideradas, e amplificadores operacionais também.
Uma referência de corrente auto polarizada com extremo baixo consumo é desenvolvida e
verificada. Um amplificador operacional original é proposto com uma topologia de seleção
de corrente mÃnima. Este circuito é constituÃdo por três estágios, com um estágio de saÃda
de classe AB, e um circuito translinear. O circuito tem em consideração redução de ruÃdo na
sua implementação.
Os circuitos são desenvolvidos com base na tecnologia 0.35mm CMOS. Uma layout foi
também desenhada com o propósito de fabricação. A tecnologia foi escolhida tendo em
conta o seu custo versus desempenho.
A referência de corrente produz uma corrente de 12nA, permanecendo estável para
tensões de alimentação de variáveis, com uma tensão mÃnima de 1.6V. O circuito mostra um
coeficiente de temperatura satisfatório. O amplificador operacional funciona com tensão de
alimentação mÃnima de 1.5V, com um consumo baixo de 8mW, com uma corrente mÃnima
mantida no estágio de saÃda
Temperature Insensitive Current Reference for the 6.27 MHz Oscillator
[[abstract]]This paper describes a circuit, which generates temperature-independent bias currents. In this paper, low- temperature coefficient reference is presented. The circuit is firstly employed to generate a current reference with temperature compensation, then combining the opposite characteristic curve current reference to minimize the variation of temperature. The proposed circuit has been design by a 0.18um CMOS technology process and using computer simulation to evaluate the thermal drift of the reference current. This current reference is used to provide a stable current for a current controlled oscillator(CCO). The proposed CCO achieves temperature coefficients of 22.3 ppm/c in the temperature range between -25 and 75c.[[conferencetype]]國際[[conferencedate]]20111212~20111214[[conferencelocation]]Singapore, Republic of Singapor
A New Temperature Independent Current Controlled Oscillator
[[abstract]]This paper describes a circuit, which generates a low temperature-dependent bias currents. In this paper, low temperature coefficient reference is presented. The circuit is firstly employed to generate a current reference with temperature compensation, then, supply current to the current controlled ring oscillator (CCO). Because of the oscillation frequency of CCO is proportional to temperature, the current is designed to be inversely proportional to temperature to compensate the temperature variation of CCO. There are four different oscillation frequency with temperature compensation has been completed, they are 10MHz, 20MHz, 30MHz and 40MHz respectively. The proposed circuit has been design by a 0.18um CMOS technology process and using computer simulation to evaluate the thermal drift of the reference current. The temperature coefficient of the proposed CCO is 24 ppm/℃ in the temperature range between -25 and 75℃ at 10MHz. In the 20MHz, 30MHz and 40MHz oscillation frequency, the temperature coefficients are 32 ppm/℃, 38 ppm/℃ and 34 ppm/℃ respectively.[[conferencetype]]國際[[conferencedate]]20111207~20111209[[iscallforpapers]]Y[[conferencelocation]]Chiang Mai, Thailan
ISM-Band Energy Harvesting Wireless Sensor Node
In recent years, the interest in remote wireless sensor networks has grown significantly, particularly with the rapid advancements in Internet of Things (IoT) technology. These networks find diverse applications, from inventory tracking to environmental monitoring. In remote areas where grid access is unavailable, wireless sensors are commonly powered by batteries, which imposes a constraint on their lifespan. However, with the emergence of wireless energy harvesting technologies, there is a transformative potential in addressing the power challenges faced by these sensors. By harnessing energy from the surrounding environment, such as solar, thermal, vibrational, or RF sources, these sensors can potentially operate autonomously for extended periods. This innovation not only enhances the sustainability of wireless sensor networks but also paves the way for a more energy-efficient and environmentally conscious approach to data collection and monitoring in various applications. This work explores the development of an RF-powered wireless sensor node in 22nm FDSOI technology working in the ISM band for energy harvesting and wireless data transmission. The sensor node encompasses power-efficient circuits, including an RF energy harvesting module equipped with a multi-stage RF Dickson rectifier, a robust power management unit, a DLL and XOR-based frequency synthesizer for RF carrier generation, and a class E power amplifier. To ensure the reliability of the WSN, a dedicated wireless RF source powers up the WSN. Additionally, the RF signal from this dedicated source serves as the reference frequency input signal for synthesizing the RF carrier for wireless data transmission, eliminating the need for an on-chip local oscillator. This approach achieves high integration and proves to be a cost-effective implementation of efficient wireless sensor nodes. The receiver and energy harvester operate at 915 MHz Frequency, while the transmitter functions at 2.45 GHz, employing On-Off Keying (OOK) for data modulation. The WSN utilizes an efficient RF rectifier design featuring a remarkable power conversion efficiency, reaching 55% at an input power of -14 dBm. Thus, the sensor node can operate effectively even with an extremely low RF input power of -25 dBm. The work demonstrates the integration of the wireless sensor node with an ultra-low-power temperature sensor, designed using 65 nm CMOS technology. This temperature sensor features an ultra-low power consumption of 60 nW and a Figure of Merit (FOM) of 0.022 [nJ.K-2]. The WSN demonstrated 55% power efficiency at a TX output power of -3.8 dBm utilizing a class E power amplifier
Analogue micropower FET techniques review
A detailed introduction to published analogue circuit design techniques using Si and Si/SiGe FET devices for very low-power applications is presented in this review. The topics discussed include sub-threshold operation in FET devices, micro-current mirrors and cascode techniques, voltage level-shifting and class-AB operation, the bulk-drive approach, the floating-gate method, micropower transconductance-capacitance and log-domain filters and strained-channel FET technologies
A Microwatt low voltage bandgap reference for bio-medical applications
In this paper a microwatt low voltage bandgap reference suitable for the bio-medical application. The Present technique relies on the principle of generating CTAT and PTAT without using any (Bipolar Junction Transistor) BJT and adding them with a proper scaling factor for minimal temperature sensitive reference voltage. Beta multiplier reference circuit has been explored to generate CTAT and PTAT. Implemented in 45nm CMOS technology and simulated with Spectre. Simulation results shows that the proposed reference circuit exhibits 1.2% variation at nominal 745mV output voltage. The circuit consumes 16uW from 0.8V supply and occupying 0.004875mm2 silicon area
Analogue micropower FET techniques review
Accepted versio
Novel Current-Mode Sensor Interfacing and Radio Blocks for Cell Culture Monitoring
Since 2004 Imperial College has been developing the world’s first application-specific
instrumentation aiming at the on-line, in-situ, physiochemical monitoring of adult stem
cell cultures. That effort is internationally known as the ‘Intelligent Stem Cell Culture
Systems’ (ISCCS) project. The ISCCS platform is formed by the functional integration
of biosensors, interfacing electronics and bioreactors. Contrary to the PCB-level
ISCCS platform the work presented in this thesis relates to the realization of a miniaturized
cell culture monitoring platform. Specifically, this thesis details the synthesis and
fabrication of pivotal VLSI circuit blocks suitable for the construction of a miniaturized
microelectronic cell monitoring platform. The thesis is composed of two main parts.
The first part details the design and operation of a two-stage current-input currentoutput
topology suitable for three-electrode amperometric sensor measurements. The
first stage is a CMOS-dual rail-class AB-current conveyor providing a low impedancevirtual
ground node for a current input. The second stage is a novel hyperbolic-sinebased
externally-linear internally-non-linear current amplification stage. This stage
bases its operation upon the compressive sinh−1 conversion of the interfaced current
to an intermediate auxiliary voltage and the subsequent sinh expansion of the same
voltage. The proposed novel topology has been simulated for current-gain values ranging
from 10 to 1000 using the parameters of the commercially available 0.8μm AMS
CMOS process. Measured results from a chip fabricated in the same technology are also
reported. The proposed interfacing/amplification architecture consumes 0.88-95μW. The second part describes the design and practical evaluation of a 13.56MHz frequency
shift keying (FSK) short-range (5cm) telemetry link suitable for the monitoring of incubated
cultures. Prior to the design of the full FSK radio system, a pair of 13.56MHz
antennae are characterized experimentally. The experimental S-parameter-value determination
of the 13.56MHz wireless link is incorporated into the Cadence Design
Framework allowing a high fidelity simulation of the reported FSK radio. The transmitter
of the proposed system is a novel multi-tapped seven-stage ring-oscillator-based
VCO whereas the core of the receiver is an appropriately modified phase locked loop
(PLL). Simulated and measured results from a 0.8μm CMOS technology chip are reported