Gm Cell Research Articles

Design and Simulation of variable gain amplifier using cadence Tool

The radio frequency (RF) amplifiers are widely used in a variety of communication systems. However, the conventional analog RF resulted in reduced volage gain, magnitude, and phase responses. So, this work provides an overview of a research paper focused on the design and analysis of a single-stage variable gain amplifier (SSVGA) utilizing cascaded linear transconductance amplifier (Gm cell) and linear transimpedance amplifier (TIA) blocks with feedback via shunt resistors. The SSVGA architecture aims to maintain constant bandwidth while offering controllable voltage gain, making it versatile for applications with varying input signal strengths. The first stage of the SSVGA is realized as a current mode TIA, converting the input voltage signal to an output current efficiently. The second stage features a Gm cell with source degeneration, enhancing bias current efficiency and transconductance at the supply voltage. The proposed SSVGA design offers flexibility and adaptability, making it suitable for diverse communication systems and signal processing applications. The incorporation of feedback control ensures consistent performance across different voltage gain settings, resulting in a robust and efficient solution for varying signal strengths.

Calotropis procera: A double edged sword against glioblastoma, inhibiting glioblastoma cell line growth by targeting histone deacetylases (HDAC) and angiogenesis

Despite substantial investments in anti-glioblastoma (GBM) drug discovery over the last decade, progress is limited to preclinical stages, with clinical studies frequently encountering obstacles. Angiogenic and histone deacetylase inhibitors (HDACi) have shown profound results in pre-clinical studies. Investigating a multicomponent anti-cancer remedy that disrupts the tumor angiogenic blood vessels and simultaneously disrupts HDACs, while inducing minimal side effects, is critically needed. The crude extracts derived from medicinal plants serve as a renewable reservoir of anti-tumor drugs, exhibiting reduced toxicity compared to chemically synthesized formulations. Calotropis procera is a traditional medicinal plant, and its anticancer potential against many cancer cell lines has been reported, however its antiangiogenic and HDAC inhibitory action is largely unknown. The anticancer activity of methanol leaf extract of C. procera was tested in three types of human glioblastoma cell lines. Wild-type and transgenic zebrafish embryos were used to evaluate developmental toxicity and angiogenic activity. A human angiogenic antibody array was used to profile angiogenic proteins in the U251 GM cell line. A real-time reverse transcriptase polymerase chain reaction (RT PCR) assay was used to detect the differential expression of eleven HDAC genes in U251 cells treated with C. procera extract. The extract significantly reduced the proliferation of all three types of GBM cell lines and the cytotoxicity was found to be more pronounced in U251 GM cells, with an IC50 value of 2.63 ± 0.23 μg/ml, possibly by arresting the cell cycle at the G2/M transition. The extract did not exhibit toxic effects in zebrafish embryos, even at concentrations as high as 1000 μg/ml. The extract also inhibited angiogenic blood vessel formation in the transgenic zebrafish model in a dose-dependent manner. The results from the angiogenic antibody array have suggested novel angiogenesis targets that can be utilized to treat GBM. Real-time RT PCR analysis has shown that C. procrea extract caused an upregulation of HDAC5, 7, and 10, while the mRNA of HDAC1, 2, 3 and 8 (Class I HDACs), and HDAC4, 6, and 9 (Class II) were downregulated in U251 GM cells. The cytotoxicity of the C. procera extract on GBM cell lines could be due to its dual action by regulation of both tumor angiogenesis and histone deacetylases enzymes. Through this study, the C. procera leaf extract has been suggested as an effective remedy to treat GBM with minimal toxicity. In addition, various novel angiogenic and HDAC targets has been identified which could be helpful in designing better therapeutic strategies to manage glioblastoma multiforme in human patients.

An Ultra Low Power Integer-N PLL with a High-Gain Sampling Phase Detector for IOT Applications in 65 nm CMOS

A low-power and low-jitter 1.2 GHz Integer-N PLL (INPLL) is designed in a 65 nm standard CMOS process. A novel high-gain sampling phase detector (PD), which takes advantage of a transconductance (Gm) cell to boost the gain, is developed to increase the phase detection gain by ~100× compared to the Phase-Frequency Detectors (PFDs) used in conventional PLLs. Using this high detection gain, the noise contribution of the PFD and Charge Pump (CP), reference clock, and dividers on the PLL output is minimized, enabling low output jitter at low power, even when using low-frequency reference clocks. To provide a sufficient frequency locking range, an auxiliary frequency-locked loop (AFLL) is embedded within the INPLL. An integrated Lock Detector (LD) helps detect the INPLL locked state and disables the AFLL to save on power consumption and minimize its impact on the INPLL jitter. The proposed INPLL layout measures 700 µm × 350 µm, consumes 350 µW, and exhibits an integrated phase noise (IPN) of −37 dBc (from 10 kHz to 10 MHz), equivalent to 2.9 ps rms jitter, while keeping the spur level 64 dBc lower, resulting in jitter figure of Merit (FoMjitter) ~−236 dB.

Automatic phase error compensation of rotary traveling wave oscillator: Analysis and design

Automatic phase error compensation of rotary traveling wave oscillator: Analysis and design

A 6-to-7.5-GHz 54-fsrms Jitter Type-II Reference-Sampling PLL Featuring a Gain-Boosting Phase Detector for In-Band Phase-Noise Reduction

This paper presents a type-II reference-sampling (RS) phase-locked loop (PLL) exploiting a novel gain-boosting reference-sampling phase detector (RSPD) to reduce the in-band phase noise and RMS jitter. The proposed gain-boosting RSPD converts the phase error to the voltage error and utilizes a passive switched-capacitor voltage multiplier to amplify the sampled voltage error, which effectively increases the gain of the RSPD. The boosted RSPD gain helps suppress the phase noise contributed from the gm cell. To prevent the transistors in the gain-boosting RSPD and gm cell from breakdown, the gain-boosting function is only activated during the locked state when the phase and voltage errors are small. The switching between the gain-boosting and normal modes is realized automatically by monitoring the sampled voltage and comparing it with a pre-defined threshold window. Fabricated in 65-nm CMOS, the type-II RS-PLL measures an RMS jitter of 54 fs at 6.75 GHz and consumes 7.1 mW, corresponding to a jitter figure-of-merit (FoMjitter) of −256.8 dB. The measured reference spur is −62.6 dBc, and the active area is 0.25 mm2.

Optimum Layout of Low Power LC-Based Digitally Controlled Oscillator for Bluetooth Low Energy in a 4G/5G LTE System

This paper presents an optimum layout method of a low-power, digitally controlled oscillator (DCO) for a Bluetooth low-energy (BLE) transceiver in a 4G/5G LTE system. For the optimal LC-based DCO layout, three different layouts, including different gm cell locations and an Al metal layer, were implemented, and performance was compared and verified for BLE application. The implemented neck DCO (NDCO), where the gm cell is located in the neck of the main inductor, showed superior performance compared to other layouts in terms of low phase noise and low power consumption. The designed NDCO had a low phase noise of −116.1 dBc/Hz at 1 MHz with a 0.5 mW power consumption. The supply voltage and oscillation frequency range were 0.8 V and 4.7–5.7 GHz, respectively, and the NDCO designed with the optimal layout had a good figure-of-merit of −192.6 dBc/Hz.

0.76-mW/pF/GHz, 7-GHz Quadrature Resonant Clock With Frequency Tuning Capacitor and Amplitude Control Feedback Loop

This brief presents a quadrature resonant clock generator for driving four 4.3-mm load wires with tuning capacitors and an amplitude control feedback loop. By using frequency tuning capacitors, which reduce the mismatch in operation and LC resonant frequencies, the proposed clock generator offers power reduction by 20-25% compared with conventional CMOS clock driver and by 23-34% compared with conventional CML clock driver over a wide voltage swing. The amplitude control feedback loop, which determines the bias current of the negative gm cell, maintains the constant optimized clock swing over wide PVT variations. Measurement result from the prototype chip fabricated in 65 nm CMOS shows that total power consumption of the proposed quadrature resonant clock is 11.92 mW in 7-GHz operation with four 559-fF load wire capacitances. Measured period jitter is 573.6 fsrms and phase noise at 1MHz offset is -138.37 dBc/Hz.

Two-Photon Absorption and Cell Imaging of Fluorene-Functionalized Epicocconone Analogues.

Epicocconone 1 is a natural chromophore isolated from the fungus Epicoccum nigrum that has shown applications in proteomics and fluorescent microscopy thanks to its unique pro-fluorescence properties. The modification of the skeleton of the natural product by replacing the triene side chain by a fluorenyl scaffold can noticeably increase the fluorophore's absorption coefficient. The synthesis of the analogues of the natural product has been made possible by the use of a palladium-catalyzed carbonylation reaction, allowing the construction of the β-keto-dioxinone key intermediate. Two-photon absorption cross-section measurements of the fluorenyl epicocconone analogues show a structure dependency with values ranging from 60 to 280 GM and live cell imaging show intense staining of intracellular vesicle-like structures around the nucleus.

0.18 mW/pole inverter‐based G m ‐C bandpass filter with automatic frequency tuning

A low-power Gm-C filter with the elliptic prototype targeting wireless application of the IEEE 802.15.4 (ZigBee) standard is presented. A modified inverter-based Gm cell is proposed to increase the current efficiency. Due to the tail current source, this Gm cell also shows better common-mode rejection and power supply rejection performance than traditional operational transconductance amplifier (OTA) structure. The filter is implemented in a 65 nm CMOS process. It achieves a figure of merit of 0.01 fJ with a power consumption of 0.18 mW/pole from a 1.2 V supply voltage. It provides stopband attenuation better than 40 dB, and an in-band IIP3 of 9 dBm. An automatic frequency tuning circuit based on sine-wave PLL method is introduced to compensate for the process variations. The centre frequency and bandwidth can be simultaneously tuned to satisfy the specifications. They are also stable over the process variations with only 2.3% deviation.

Sink ? Source System of In vitro Suspension Culture of Celastrus paniculatus under Regulation of Monochromatic Lights

Plants are wonderful resource of bioproducts encompassing significant value to medicines and drug development. The plant cell suspension cultures bear immense potential for production of high?value secondary metabolites and are chosen as alternative sources of raw material for industrial use. In the present study, homogenous cell suspension culture of Celastrus paniculatus a medicinally important plant was established and multifold production of alkaloids and total phenols was obtained under the influence of monochromatic lights. One month old leaf derived friable callus of C. paniculatus was used to raise homogenous suspension culture and kept on rotary shakers in cabinets illuminated with different monochromatic LED lights (Blue, Yellow and Red). The monochromatic lights proved to be a strong abiotic elicitor in driving the production of secondary metabolites so much so that the metabolites were released extracellularly and the medium served as sink or spacious pool for leaked out metabolites from the cell mass. Maximum production and enhancement in alkaloids and phenols (98 and 44.7%, respectively) over control was obtained from cell mass grown under yellow light treatment, followed by blue (64 and 23.7%) and red light (50 and 26%) treatments. Further scale up of secondary metabolite production was hence performed under yellow light conditions, starting from 2.5 gm cell mass suspended in 250 ml of media extended up to 1000 ml culture media for one month. The continuous culture system exhibited remarkable potential of this plant cell system as multifold yield of total alkaloids (91.69 ?g/1750 ml) and phenols (70.59 ?g/1750 ml) was obtained during 30 days of culture under yellow light conditions. The production was remarkably enhanced by 100?folds (5.29 to 48.21 ?g; Fig. 2) for alkaloids and 70?folds (1.73 to 46.33 ?g; Fig. 3) for phenols, from zero days to 30?day?old culture phase. Hence, strategic implementation of monochromatic lights holds great promises for controlled commercial production of myriads of valuable secondary metabolites from plant cell cultures of important medicinal plants. Present work contributes to the first reports where continuous, enhanced, multifold yield of important secondary metabolites were obtained from cell suspension culture of Celasrus paniculatus an endangered medicinal plant.Plant Tissue Cult. & Biotech. 26(2): 175-185, 2016 (December)

Harmonic fold back reduction at the N‐path filters

SummaryIn this paper, a method is proposed to reduce harmonic fold back (HFB) problem of N‐path filters, without increasing the input reference clock (fCLK) frequency. The HFB at the N‐path filter is analyzed, and simple expressions are extracted to model this problem. Using the results of the analysis, an M‐of‐N‐path filter has been proposed that behaves like an M × N‐path filter in terms of HFB problem; however, the fCLK frequency of this structure is the same as an N‐path filter. To demonstrate the feasibility of the proposed idea, a 3‐of‐4‐path filter is designed, and its characteristics are compared with 4‐path and 12‐path filters by simulation. Impacts of different non‐idealities like clock‐phase error, mismatch, and parasitic capacitance are investigated. The transistor‐level implementation of this filter is performed in 0.18 µm Complementary Metal Oxide Semiconductor (CMOS) technology. The simulation results show that the filter has the pass‐band gain of 17 dB, tuning range of 0.2–1.2 GHz, −3 dB bandwidth of 25 MHz, quality factor of 8–48, 18 dB out‐of‐band rejection, 16 dB rejection of the third harmonic of switching frequency (fs), and the noise figure of 4.35 dB (using ideal Gm cells) and 6.95 dB (for practical Gm cells). The strongest harmonic folding to the filter pass‐band occurs around 11fs with the attenuation of 23.8 dB. Each Gm cell draws about 12.4 mA from 1.8 V supply, and the out‐of‐band IIP3 and P1 dB,CP are 17 and 4 dBm, respectively. Copyright © 2016 John Wiley & Sons, Ltd.

I/Q mismatch calibration of a transmitter using local quadrature oscillator

In this paper a calibration technique for I/Q mismatch of a transmitter is introduced. The calibration technique is based on the fact that all mismatches in I/Q paths can be modeled as the mismatch of the local oscillator quadrature outputs. Based on this fact, a simple tuning scheme for quadrature output of the oscillator is used to calibrate the mismatch of the I/Q transmitter. In addition to quadrature oscillator, gain mismatch of the I/Q paths and LO feedthorugh and leakage is calibrated by using a tunable linear Gm cell in the base band part. In order to demonstrate the proposed technique, a transmitter with 1.8GHz carrier frequency is designed with auxiliary blocks to extract and cancel out the I/Q mismatches. The simulation results in 0.18µm RFCMOS process show that the proposed technique can reduce amplitude of the image signal resulting from mismatches in I/Q paths about 18.5dB in the transmitter output.

A CMOS Distributed Amplifier With Distributed Active Input Balun Using GBW and Linearity Enhancing Techniques

A CMOS distributed amplifier (DA) with distributed active input balun is presented that achieves a gain-bandwidth product of 818 GHz, while improving linearity. Each gm cell within the DA employs dual-output two-stage topology that improves gain and linearity without adversely affecting bandwidth (BW) and power. Comprehensive analysis and simulations are carried out to investigate gain, BW, linearity, noise, and stability of the proposed gm cell, and compare them with conventional gm cells. Fabricated in a 65-nm low-power CMOS process, the 0.9-mm2 DA achieves 22 dB of gain and a P1dB of 10 dBm, while consuming dc power of 97 mW from a 1.3-V supply. A distributed balun, designed and fabricated in the same process, using the same gm topology achieves a BW larger than 70 GHz and a gain of 4 dB with 19.5-mW power consumption from 1.3-V supply.

CMOS on-chip active RF tracking filter for digital TV tuner ICs

A full frequency band active RF tracking filter design for a digital TV tuner is implemented for the first time. By combined control of the Gm and C values in the biquad of the Gm - C filter, the proposed tracking bandpass filter satisfies full frequency band tuning while maintaining narrow bandwidth. The Gm cell of the tracking filter is based on a dynamic source degenerated differential pair with optimised transistor size ratio, which provides good linearity and high-frequency operation. The fabricated tracking filter based on a 0.13 μm CMOS process shows 48 780 MHz tracking range with 15 60 MHz bandwidth, more than 50 dB of third-order harmonic rejection, 14 dB unwanted signal rejection at N + 6 channel offset, and a maximum IIP3 of 3.8 dBm at 4.7 dB gain while drawing 30 mA from a 1.2 V supply.

A Low Power and Low Noise On-Chip Active RF Tracking Filter for Digital TV Tuner ICs

In this paper, a highly linear and low noise CMOS active RF tracking filter for a digital TV tuner is presented. The Gm cell of the Gm-C filter is based on a dynamic source degenerated differential pair with an optimized transistor size ratio, thereby providing good linearity and high-frequency operation. The proposed RF tracking filter architecture includes two complementary parallel paths, which provide harmonic rejection in the low band and unwanted signal rejection in the high band. The fabricated tracking filter based on a 0.13µm CMOS process shows a 48∼860MHz tracking range with 30-32dB 3rd order harmonic rejection, a minimum input referred noise density of 2.4nV/√Hz, and a maximum IIP3 of 0dBm at 3dB gain while drawing 39mA from a 1.2-V supply. The total chip area is 1mm × 0.9mm.

70–280 MHz 21 mW 53 dB SFDR Gm-C filter

A 70–280 MHz fifth-order Chebyshev Gm-C lowpass filter in 0.13 µm CMOS is presented. A topological modification is proposed that can improve IIP3 for 10 dB compared to conventional Gm-C filters. Measured spurious free dynamic range (SFDR) is greater than 50 dB. The filter passband response is accurately maintained over four times frequency range by using unit Gm cell arrays and an independent Q tuning circuit. It consumes 21 mW under a supply voltage of 1.5 V and occupies an area of 0.12 mm2.

Wideband LNA Using a Negative gm Cell for Improvement of Linearity and Noise Figure

A differential common gate low noise amplifier (LNA) has been widely used for a wideband LNA. However, it has poor linearity due to a nonlinear transconductance in a MOSFET and poor noise performances from the common gate configuration. We propose a differential common gate LNA with a negative g m cell for the improvement of the linearity and noise figure. The cell comprises cross coupled transistors instead of a current source. The negative g m cell creates the opposite phased harmonic, canceling the distortion. The noise figure is improved by canceling the noise from the common gate transistors through the negative g m cell. The LNA is fabricated in 0.13 μm RF CMOS. The LNA has the bandwidth of 0.7 ∼ 3.5 GHz frequency and has provided the expected characteristics for linearity and noise figure.

A fifth-order gm–c continuous-time Δ Σ modulator with process-insensitive input linear range

Continuous-time ?? modulators (CT-DSMs) that use transistor-based Gm-C integrators are simple but sensitive to process and temperature variations. Their performance depends heavily on the input linear range that varies widely. A CT-DSM is implemented using a triode Gm-C integrator and a tri-level switched-capacitor digital-to-analog converter (SCDAC). A self-scaling SCDAC keeps the input signal range constant, and an adaptive input common-mode bias control enables the triode Gm cell to operate always with its constant input linear range. The proposed Gm cell exhibits a tuning range of ± 15% while maintaining its linear range over the temperature variation from -30°C to 85°C. A 2-MHz bandwidth, fifth-order CT-DSM in 0.18 ?m CMOS samples at 128 MS/s with an over-sampling ratio of 32 (OSR = 32), occupies an active area of 0.4 mm2, and consumes 11 mW at 1.8 V. With a -3 dB input of the full scale (400 mV), the measured dynamic range, second harmonic distortion (HD2), and third harmonic distortion (HD3) are 71, -86, and -91 dB, respectively.

Specific Detection of CD56 (NCAM) Isoforms for the Identification of Aggressive Malignant Neoplasms with Progressive Development

Alternative splicing of transcripts from many cancer-associated genes is believed to play a major role in carcinogenesis as well as in tumor progression. Alternative splicing of one such gene, the neural cell adhesion molecule CD56 (NCAM), impacts the progression, inadequate therapeutic response, and reduced total survival of patients who suffer from numerous malignant neoplasms. Although previous investigations have determined that CD56 exists in three major isoforms (CD56(120kD), CD56(140kD), and CD56(180kD)) with individual structural and functional properties, neither the expression profiles nor the functional relevance of these isoforms in malignant tumors have been consistently investigated. Using new quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) strategies and novel CD56 isoform-specific antibodies, CD56(140kD) was shown to be exclusively expressed in a number of highly malignant CD56(+) neoplasms and was associated with the progression of CD56(+) precursor lesions of unclear malignant potential. Moreover, only CD56(140kD) induced antiapoptotic/proliferative pathways and specifically phosphorylated calcium-dependent kinases that are relevant for tumorigenesis. We conclude, therefore, that the specific detection of CD56 isoforms will help to elucidate their individual functions in the pathogenesis and progression of malignant neoplasms and may have a positive impact on the development of CD56-based immunotherapeutic strategies.

Lineage Instructive Function of C/EBPα in Multipotent Hematopoietic Progenitor Cells Revealed in a Novel Cebpa-Cre Knock-in Model

Transcription factors control the lineage specification and differentiation of hematopoietic progenitor cells. They are expressed in a cell type-restricted pattern and activate lineage specific genetic programs. Recent studies have demonstrated that expression of GATA-1 or PU.1 in multipotent lin−Sca-1+c-Kit+ (LSK) cells specifies them to develop into myeloerythroid progenitors or lymphomyeloid progenitors, respectively. In contrast, C/EBPα, a transcription factor indispensable for the production of granulocytes and macrophages, is thought to predominantly act at a later stage of hematopoietic commitment, by governing the transition from common myeloid progenitors (CMPs) into granulocytic/monocytic progenitors (GMPs). To study whether C/EBPα may already exert a lineage instructive function at an earlier stage of hematopoietic cell development, i.e., at the level of multipotent LSK cells, we generated a knock-in mouse model expressing Cre recombinase under the regulation of the cebpa promoter and crossed C/EBPαcre/+ mice with R26 YFP reporter mice. This model faithfully demonstrates high levels of C/EBPα expression in myeloid cells and enabled us to trace cebpa-driven Cre/YFP expression in single LSK cells and their progeny by flow cytometry and colony cultures. On average cebpa-driven YFP expression was found in 17% (range 10–25%) of the total LSK fraction (n=12 mice). Within the CD150+CD48− CD34− subset of LSK cells, which contains the most primitive hematopoietic stem cells (HSC), 3–8% of the cells expressed YFP, indicating that cebpa is lowly expressed in bona fide HSC. This low level of expression appears insufficient for lineage determination, since the same levels of YFP expression (1–10%) were found in peripheral T and B cells. Within the CD34+ fraction of LSK cells, a population enriched for multipotent progenitors, 19% (range 14%–28%) of the cells expressed YFP. Identical distributions of YFP+ cells among the different LSK subsets were found in fetal livers of day 14.5 embryos, suggesting a comparable regulation of cebpa expression in fetal and adult cells. Similar to the reported data for GATA-1 and PU.1, cebpa-expressing LSK cells were predominantly found in the Sca-1low fraction. When cultured in a multilineage cytokine cocktail, YFP+ LSK cells gave predominantly rise to GM colonies (73% of all colonies; range 65–85%), whereas YFP− cells formed multiple types of colonies including mixed, megakaryocytic and erythroid colonies. The predominant outgrowth of YFP+ LSK cells to GM lineages was further supported in GM-CSF-supplemented colony assays, which gave rise to cloning efficiencies of 26% for YFP+ and 4% for YFP− LSK cells, respectively. In conclusion, our results show that C/EBPα starts to exert its instructive function towards GM cell development already within the LSK population, at the level of the multipotent progenitors. This has important ramifications for our understanding of the role of C/EBPα in early hematopoietic cell fate decisions.