Mohamed A. Y. Abdalla

Printed and Integrated CMOS Positive/Negative Refractive-Index Phase Shifters Using Tunable Active Inductors

This paper presents a printed and an integrated bi-directional tunable positive/negative refractive-index phase shifter utilizing CMOS tunable active inductors (TAIs). The printed phase shifter is comprised of a microstrip transmission line (TL), loaded with series varactors and a shunt monolithic microwave integrated circuit (MMIC) synthesizing the TAI. Using the TAI extends the phase tuning range and results in a low return loss across the entire tuning range. The integrated circuit (IC) phase shifter replaces the TLs with suitable lumped L-C sections. This enables integrating the entire phase shifter on a single MMIC, resulting in a compact implementation. The TAI used for both phase shifters is based on a modified gyrator-C architecture, employing a variable resistance to independently control the inductance and quality factor. The TAI is fabricated in the 0.13-mum CMOS process and operates from a 1.5-V supply. The TAI chip is used to implement the TL phase shifter, which achieves a phase of -40deg to +34deg at 2.5 GHz with less than -19-dB return loss from a single stage occupying 10.8 mm times 10.4 mm. The IC phase shifter is fabricated in the same process and achieves a phase from -35deg to +59deg at 2.6 GHz with less than -19-dB return loss from a single stage occupying 550 mum times 1300 mum.

A Compact Highly Reconfigurable CMOS MMIC Directional Coupler

This paper presents a tunable CMOS directional coupler that utilizes lumped-element L-C sections. The lumped-element approach used to build the directional coupler makes it possible to integrate the coupler onto a single monolithic microwave integrated circuit (MMIC), as it occupies a small area compared to printed designs. The directional coupler uses varactors and tunable active inductors (TAIs) to synthesize the series and shunt reactances, respectively, which allows extensive electronic control over the coupling coefficient, while insuring a low return loss and a very high isolation. Furthermore, using varactors and TAIs allows the directional coupler to be reconfigured for operation over a wide range of frequencies. Moreover, the symmetric configuration of the coupler allows it to switch from forward to backward operation by simply exchanging the bias voltages applied across the series varactors. The MMIC coupler was fabricated in a standard 0.13-mum CMOS process and operates from a 1.5-V supply. The circuit occupies 730 mum times 600 mum, and is capable of achieving tunable coupling coefficients from 1.4 to 7.1 dB, while maintaining an isolation higher than 41 dB. The MMIC coupler is also capable of operating at any center frequency over the 2.1-3.1-GHz frequency range with higher than 40-dB isolation. The coupler achieves a -4.1-dBm 1-dB compression point while operating from a 1.5-V supply.

A 0.13-

This letter presents a tunable positive/negative refractive index transmission line (TL) phase shifter utilizing active circuits. It comprises a microstrip TL loaded with series varactors and a shunt monolithic microwave integrated circuit (MMIC) to synthesize a tunable inductor. This implementation increases the phase tuning range and maintains the input and output matching of the phase shifter across the entire phase tuning range, while eliminating the need for bulky passive inductors. The phase shifter is capable of providing both positive and negative phase shifts. The MMIC tunable inductors are fabricated in a 0.13-mum CMOS process and operate from a 1.5-V supply. The phase shifter achieves a phase of -40deg to +34deg at 2.5GHz from a single stage with less than -19dB return loss, and better than 1.1-dB insertion loss at 2.5 GHz. The phase shifter has a 1-GHz bandwidth over which the return loss remains better than 12.1dB

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This paper presents a novel differential 0.13mum CMOS active inductor circuit, which is employed in the design of an integrated negative refractive index metamaterial phase shifter. The active inductor circuit employs a digital/analog tunable feedback resistance to allow controlling both the inductance and the quality factor. The inductance is tunable from 2.5nH to 13.6nH at 5GHz while having a fixed peak quality factor of 100. This results in a phase shift of 36.7deg/stage, at 5GHz, with less than 0.67dB insertion loss

m CMOS Phase Shifter Using Tunable Positive/Negative Refractive Index Transmission Lines

This paper presents an integrated phase shifter based on the high-pass L-C topology. The circuit utilizes both varactors and active inductors to extend the tuning range and achieve a low return loss. The high-pass topology results in a compact IC implementation, and allows phase compensation in series-fed antenna arrays utilizing this phase shifter. Furthermore, this approach allows integrating multiple stages on the same IC, without a significant size increase. A negative resistance is generated by the active inductor circuit, and is used to partially compensate the varactor losses. A test chip is fabricated in a standard 0.13 mum CMOS process, and a phase tuning range of 96deg is achieved at 4 GHz, with a return loss better than -18 dB across the entire tuning range. The phase shifter achieves a -2.2 dBm input compression point and a 7.4 dBm IIP3 while operating from a 1.5 V supply.

A differential 0.13/spl mu/m CMOS active inductor for high-frequency phase shifters

This paper presents a novel tunable metamaterial-based phase-shifter structure utilizing active circuits. It comprises a microstrip transmission line loaded with series varactors and tunable active shunt inductors to increase the phase tuning range and maintain the input & output matching of the metamaterial phase shifter. The proposed phase shifter is capable of providing both a positive and negative phase shift. The active inductors are fabricated in a 0.13mum CMOS process and operate from a 1.5V supply, a 1:2.9 inductance tuning range is measured at 2.5GHz with a tunable peak quality factor >100. The performance of the metamaterial phase shifter unit-cell is simulated using the measured active inductor S-parameters, it achieves a phase tuning range of plusmn20deg at 2.5GHz, with <0.6dB insertion loss and better than -30dB reflection loss

A Bi-Directional Electronically Tunable CMOS Phase Shifter Using the High-Pass Topology

This paper presented a steerable series-fed phased array architecture using zero-degree tunable positive/negative-refractive-index (PRI/NRI) phase shifters. Using PRI/NRI phase shifters centered around the 0deg mark makes the array capable of steering its beam off broadside. The patch antennas of the array are moved off the centerline of the main feed line allowing for the inclusion of impedance transformers, which in turn, allows using identical inter-stage phase shifters, and allows using the same bias/control voltages to tune all stages.

A Tunable Metamaterial Phase-Shifter Structure Based on a 0.13μm CMOS Active Inductor

Almost all genomic studies of breast cancer have focused on well-established tumours because it is technically challenging to study the earliest mutational events occurring in human breast epithelial cells. To address this we created a unique dataset of epithelial samples ductoscopically obtained from ducts leading to breast carcinomas and matched samples from ducts on the opposite side of the nipple. Here, we demonstrate that perturbations in mRNA abundance, with increasing proximity to tumour, cannot be explained by copy number aberrations. Rather, we find a possibility of field cancerization surrounding the primary tumour by constructing a classifier that evaluates where epithelial samples were obtained relative to a tumour (cross-validated micro-averaged AUC = 0.74). We implement a spectral co-clustering algorithm to define biclusters. Relating to over-represented bicluster pathways, we further validate two genes with tissue microarrays and in vitro experiments. We highlight evidence suggesting that bicluster perturbation occurs early in tumour development.Studying the spatial mutational and gene expression alterations in breast cancer could impact our understanding of breast cancer development. Here, the authors analyse a unique dataset of epithelial samples that highlight potential field cancerisation surrounding the primary tumour.

A Steerable Series-fed Phased Array Architecture Using Tunable PRI/NRI Phase Shifters

Genome wide association studies (GWASs) for complex traits have implicated thousands of genetic loci. Most GWAS-nominated variants lie in noncoding regions, complicating the systematic translation of these findings into functional understanding. Here, we leverage convolutional neural networks to assist in this challenge. Our computational framework, peaBrain, models the transcriptional machinery of a tissue as a two-stage process: first, predicting the mean tissue specific abundance of all genes and second, incorporating the transcriptomic consequences of genotype variation to predict individual abundance on a subject-by-subject basis. We demonstrate that peaBrain accounts for the majority (>50%) of variance observed in mean transcript abundance across most tissues and outperforms regularized linear models in predicting the consequences of individual genotype variation. We highlight the validity of the peaBrain model by calculating non-coding impact scores that correlate with nucleotide evolutionary constraint that are also predictive of disease-associated variation and allele-specific transcription factor binding. We further show how these tissue-specific peaBrain scores can be leveraged to pinpoint functional tissues underlying complex traits, outperforming methods that depend on colocalization of eQTL and GWAS signals. We subsequently derive continuous dense embeddings of genes for downstream applications, and identify putatively functional eQTLs that are missed by high-throughput experimental approaches.

Mapping genomic and transcriptomic alterations spatially in epithelial cells adjacent to human breast carcinoma.

ABSTRACT Background: Language is one of the first faculties afflicted by Alzheimer’s disease (AD). A growing body of work has focussed on leveraging automated analysis of speech to accurately predict the onset of AD. Previous work, however, did not address the effects of AD on the structure of discourse in spontaneous speech and literature. Aims: Our goal is to identify the effects of AD on the structure of discourse, both in spontaneous speech and in literature. Methods & Procedures: We use two existing data sets, DementiaBank and the Carolina Conversations Collection, to explore how AD manifests itself in spontaneous speech. This is done by automatically extracting discourse relations according to Rhetorical Structure Theory. We also study written novels, comparing authors with and without dementia using the same tools. Outcomes & Results: Several discourse relations, especially those involving elaboration and attribution, are significant indicators of AD in speech. Indicators of the disease in written text, by contrast, involve relations of logical contingency. Conclusions: Our work highlights how AD can alter discourse structures in both spontaneous speech and written text. Future work should combine discourse analysis with previously studied lexico-syntactic features.