1,721,010 research outputs found
Analysis and Design of Radio Frequency Integrated Circuits for Breast Cancer Radar Imaging in CMOS Technology
Full text linkBreast cancer is by far the most incident tumor among female population. Early stage prevention is a key factor in delivering long term survival of breast cancer patients. X-ray mammography is the most commonly used diagnostic technique to detect non-palpable tumors. However, 10-30% of tumors are missed by mammography and ionizing radiations together with breast compression do not lead to comfort in patient treatment. In this context, ultrawideband microwave radar technology is an attractive alternative. It relies on the dielectric contrast of normal and malignant tissues at microwave frequencies to detect and locate tumors inside the breast. This work presents the analysis and design of radio frequency integrated circuits for breast cancer imaging in CMOS technology.
The first part of the thesis concerns the system analysis. A behavioral model of two different transceiver architectures for UWB breast cancer imaging employing a SFCW radar system are presented. A mathematical model of the direct conversion and super heterodyne architectures together with a numerical breast phantom are developed. FDTD simulations data are used to on the behavioral model to investigate the limits of both architectures from a circuit-level point of view. Insight is given into I/Q phase inaccuracies and their impact on the quality of the final reconstructed images. The result is that the simplicity of the direct conversion architecture makes the receiver more robust toward the critical impairments for this application.
The second part of the thesis is dedicated to the circuit design. The main achievement is a 65nm CMOS 2-16GHz stepped frequency radar transceiver for medical imaging. The RX features 36dB conversion gain, >29dBm compression point, 7dB noise figure, and 30Hz 1/f noise corner. The TX outputs 14dBm with >40dBc harmonic rejection and <109dBc/Hz phase noise at 1MHz offset. Overall power dissipation is 204mW from 1.2V supply. The radar achieves 3mm resolution within the body, and 107dB dynamic range, a performance enabling the use for breast cancer diagnostic imaging. To further assess the capabilities of the proposed radar, a physical breast phantom was synthesized and two targets mimicking two tumors were buried inside the breast. The targets are clearly identified and correctly located, effectively proving the performance of the designed radar as a possible tool for breast cancer detection
Transparency and Product Differentiation with Competing Vertical Hierarchies
No full textWe revisit the choice of product differentiation by competing firms in the Hotelling model, by assuming that firms are vertically separated, and that retailers choose products' characteristics. We show that retailers with private information about their marginal costs produce less differentiated products than manufacturers or retailers with no private information, in order to increase their information rents. Hence, information asymmetry within firms may increase social welfare by inducing them to sell products that appeal to a larger number of consumers. The socially optimal level of transparency between manufacturers and retailers depends on the weight assigned to consumers' surplus and trades off two effects: higher transparency reduces price distortion but induces retailers to produce excessively similar products
Entry and Product Variety with Competing Supply Chains
Full text linkWe study a model where an endogenous number of competing manufacturers located around a circle contract with exclusive retailers who are privately informed about their costs. The number of brands in the market (determined by the manufacturers’ zero profit condition) depends on the presence of asymmetric information and on the types of contracts between manufacturers and retailers. With two‐part tariffs, wholesale prices fully reflect retailers’ costs; with linear contracts, wholesale prices are constant and independent of retailers’ costs. The number of brands is lower (resp. higher) with asymmetric information than with complete information when contracts are linear (resp. with two‐part tariffs). Moreover, although the number of brands is always higher with linear contracts than with two‐part tariffs, joint profits of manufacturers and retailers are higher with linear prices. We also discuss manufacturers’ incentives to choose different contract forms and analyze the effects of endogenous entry on welfare
A High-Swing 45 Gb/s Hybrid Voltage and Current-Mode PAM-4 Transmitter in 28 nm CMOS FDSOI
Full text link— Pushed by the ever-increasing demand of high-speed
connectivity, next generation 400 Gb/s electrical links are targeting
PAM-4 modulation to limit channel loss and preserve
link budget. Compared to NRZ, a higher amplitude is desirable
to counteract the 1/3 reduction of PAM-4 vertical eye opening.
However, linearity is also key, and PAM-4 levels must be precisely
spaced to preserve the horizontal eye opening advantage it has
over NRZ. This paper presents a 45 Gb/s PAM-4 transmitter
able to deliver a very large output swing with enhanced linearity
and state-of-the-art efficiency. Built around a hybrid combination
of current-mode and voltage-mode topologies, the driver is
embedded into a 4-taps 5-bits feed-forward equalizer (FFE),
and allows tuning the output impedance to ensure good source
termination. Implemented in 28 nm CMOS FDSOI process,
the full transmitter includes a half-rate serializer, duty-cycle
correction circuit, >> 2 kV HBM ESD diodes, and delivers a
full swing of 1.3 Vppd at 45 Gb/s, while drawing only 120 mA
from 1 V supply. The power efficiency is ∼ 2 times better than
previously reported PAM-4 transmitter
A 24 GHz Quadrature VCO Based on Coupled PLL with -134 dBc/Hz Phase Noise at 10 MHz Offset in 28 nm CMOS
No full textWideband 2–16GHz Local Oscillator Generation for Short-Range Radar Applications
No full textA 65 nm CMOS LO generation system capable of
providing quadrature signals over the wide 2 to 16GHz frequency
range for short-range radar applications is presented. Made of
a 6.5 to 18.4GHz PLL, and an injection-locked programmable
divider by 1, 2, or 4, it features a phase noise at 10MHz offset
< −129 dBc/Hz, a RMS jitter < 0.68 ps, a reference spur level
< −48 dBc, and a settling time of 2 μs
A 65-nm CMOS 1.75-15 GHz Stepped Frequency Radar Receiver for Early Diagnosis of Breast Cancer
No full textA 65-nm CMOS receiver tailored for breast cancer diagnostic imaging is demonstrated for the first time. The receiver shows 31-dB conversion gain, NF -28dBm, IIP3 >-12dBm and IIP2>22dBm over a band from 1.75 to 15 GHz. A programmable injection-locked divider generates quadrature LO signals with a I/Q phase error <1.5deg over three octaves without requiring any calibration or tuning. The receiver shows a flicker noise corner as low as 40 Hz, achieving a dynamic range of 106 dB
Optimal Contracting with Altruism and Reciprocity
No full textMotivated by the recent experimental evidence on altruistic behavior, we study a simple principal–agent model where each player cares about other players' utility, and may reciprocate their attitude towards him. We show that, relative to the selfish benchmark, efficiency improves when players are altruistic. Nevertheless, in contrast to what may be expected, an increase in the degree of the agent's altruism as well as a more reciprocal behavior by players has ambiguous effects on efficiency. We also consider the effects of the presence of spiteful players and discuss how monetary transfers between players depend on their degrees of altruism and spitefulness
Integrated SFCW Transceivers for UWB Breast Cancer Imaging: Architectures and Circuit Constraints
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