Guest editorial for the special issue on software-defined radio transceivers and circuits for 5G wireless communications

Yichuang Sun, Baoyong Chi, and Heng Zhang, Guest Editorial for the Special Issue on Software-Defined Radio Transceivers and Circuits for 5G Wireless Communications, published in IEEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 63 (1): 1-3, January 2016, doi: https://doi.org/10.1109/TCSII.2015.2506979.Peer reviewedFinal Accepted Versio

A 0.1–5.0 GHz flexible SDR receiver with digitally assisted calibration in 65 nm CMOS

© 2017 Elsevier Ltd. All rights reserved.A 0.1–5.0 GHz flexible software-defined radio (SDR) receiver with digitally assisted calibration is presented, employing a zero-IF/low-IF reconfigurable architecture for both wideband and narrowband applications. The receiver composes of a main-path based on a current-mode mixer for low noise, a high linearity sub-path based on a voltage-mode passive mixer for out-of-band rejection, and a harmonic rejection (HR) path with vector gain calibration. A dual feedback LNA with “8” shape nested inductor structure, a cascode inverter-based TCA with miller feedback compensation, and a class-AB full differential Op-Amp with Miller feed-forward compensation and QFG technique are proposed. Digitally assisted calibration methods for HR, IIP2 and image rejection (IR) are presented to maintain high performance over PVT variations. The presented receiver is implemented in 65 nm CMOS with 5.4 mm2 core area, consuming 9.6–47.4 mA current under 1.2 V supply. The receiver main path is measured with +5 dB m/+5dBm IB-IIP3/OB-IIP3 and +61dBm IIP2. The sub-path achieves +10 dB m/+18dBm IB-IIP3/OB-IIP3 and +62dBm IIP2, as well as 10 dB RF filtering rejection at 10 MHz offset. The HR-path reaches +13 dB m/+14dBm IB-IIP3/OB-IIP3 and 62/66 dB 3rd/5th-order harmonic rejection with 30–40 dB improvement by the calibration. The measured sensitivity satisfies the requirements of DVB-H, LTE, 802.11 g, and ZigBee.Peer reviewedFinal Accepted Versio

A 10-b Fourth-Order Quadrature Bandpass Continuous-Time ΣΔ Modulator With 33-MHz Bandwidth for a Dual-Channel GNSS Receiver

This document is the Accepted Manuscript version of the following article: Junfeng Zhang, Yang Xu, Zehong Zhang, Yichuang Sun, Zhihua Wang, and Baoyong Chi, ‘A 10-b Fourth-Order Quadrature Bandpass Continuous-Time ΣΔ Modulator With 33-MHz Bandwidth for a Dual-Channel GNSS Receiver’, IEEE Transactions on Microwave Theory and Practice, Vol. 65 (4): 1303-1314, first published online 16 February 2017. The version of record is available online at DOI: 10.1109/TMTT.2017.266237, Published by IEEE. © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A fourth-order quadrature bandpass continuous-time sigma-delta modulator for a dual-channel global navigation satellite system (GNSS) receiver is presented. With a bandwidth (BW) of 33 MHz, the modulator is able to digitalize the downconverted GNSS signals in two adjacent signal bands simultaneously, realizing dual-channel GNSS reception with one receiver channel instead of two independent receiver channels. To maintain the loop-stability of the high-order architecture, any extra loop phase shifting should be minimized. In the system architecture, a feedback and feedforward hybrid architecture is used to implement the fourth-order loop-filter, and a return-to-zero (RZ) feedback after the discrete-time differential operation is introduced into the input of the final integrator to realize the excess loop delay compensation, saving a spare summing amplifier. In the circuit implementation, power-efficient amplifiers with high-frequency active feedforward and antipole-splitting techniques are employed in the active RC integrators, and self-calibrated comparators are used to implement the low-power 3-b quantizers. These power saving techniques help achieve superior figure of merit for the presented modulator. With a sampling rate of 460 MHz, current-steering digital-analog converters are chosen to guarantee high conversion speed. Implemented in only 180-nm CMOS, the modulator achieves 62.1-dB peak signal to noise and distortion ratio, 64-dB dynamic range, and 59.3-dB image rejection ratio, with a BW of 33 MHz, and consumes 54.4 mW from a 1.8 V power supply.Peer reviewe

A Fully-Integrated Reconfigurable Dual-Band Transceiver for Short Range Wireless Communications in 180 nm CMOS

© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.A fully-integrated reconfigurable dual-band (760-960 MHz and 2.4-2.5 GHz) transceiver (TRX) for short range wireless communications is presented. The TRX consists of two individually-optimized RF front-ends for each band and one shared power-scalable analog baseband. The sub-GHz receiver has achieved the maximum 75 dBc 3rd-order harmonic rejection ratio (HRR3) by inserting a Q-enhanced notch filtering RF amplifier (RFA). In 2.4 GHz band, a single-ended-to-differential RFA with gain/phase imbalance compensation is proposed in the receiver. A ΣΔ fractional-N PLL frequency synthesizer with two switchable Class-C VCOs is employed to provide the LOs. Moreover, the integrated multi-mode PAs achieve the output P1dB (OP1dB) of 16.3 dBm and 14.1 dBm with both 25% PAE for sub-GHz and 2.4 GHz bands, respectively. A power-control loop is proposed to detect the input signal PAPR in real-time and flexibly reconfigure the PA's operation modes to enhance the back-off efficiency. With this proposed technique, the PAE of the sub-GHz PA is improved by x3.24 and x1.41 at 9 dB and 3 dB back-off powers, respectively, and the PAE of the 2.4 GHz PA is improved by x2.17 at 6 dB back-off power. The presented transceiver has achieved comparable or even better performance in terms of noise figure, HRR, OP1dB and power efficiency compared with the state-of-the-art.Peer reviewe

The preparation of titanium carbide thin film of Ti6Al4V at low temperature and study of friction and wear properties

In this article, the technology of salt bath carburizing at low temperature (640 °C) is used to prepare the titanium carbide thin film on Ti6Al4V alloy surface. The processed alloy sample surface phase and elements are observed by XRD and EDAX. The hardness of sample surface and permeability layer are measured by the MH-3 type microhardness meter. And the friction and wear contrast tests of the uncarburized and carburized samples are carried out using the M2000 friction and wear testing machine. The results show that: high hard phase carbide Ti8C5 is generated on the sample surface. The processed sample surface hardness is 953.28HV, which is 2.57 times of the original; The friction and wear properties of the carburized sample improve significantly; At 100 N, the uncarburzed wearing loss is 29 times of the carburized wearing loss, and at 300 N, the friction coefficient is reduced by 55.9 %

Mechanics-Seepage Experimental and Simulation Study of Gas-Bearing Coal under Different Load Paths

Mechanics-seepage synchronous tests on gas-bearing coal under three different stress paths were designed and implemented to evaluate how load path affected the mechanical strength and permeability of deep mining-disturbed coal. The cracks-count evolution of coal specimens during instability was observed through DEM numerical simulation. The results showed significant stress-strain and strength variations under different paths. At the time of failure, the specimen deformation and peak strength were Test 1 > Test 2 > Test 3, while the permeability was Test 3 > Test 2 > Test 1, with specimen permeability in Test 3 rising prominently. From numerical simulation, the cracks count was Test 2 > Test 3 > Test 1, with tensile cracks taking the largest proportion in Test 2 and shear cracks taking the largest proportion in Test 3. Our findings shed some light on the research and disaster prevention regarding coal and gas outburst

Activation of tyrosine hydroxylase mRNA translation by cAMP in midbrain dopaminergic neurons. Mol Pharmacol 73:1816–1828.

ABSTRACT During prolonged stress or chronic treatment with neurotoxins, robust compensatory mechanisms occur that maintain sufficient levels of catecholamine neurotransmitters in terminal regions. One of these mechanisms is the up-regulation of tyrosine hydroxylase (TH), the enzyme that controls catecholamine biosynthesis. In neurons of the periphery and locus coeruleus, this up-regulation is associated with an initial induction of TH mRNA. In contrast, this induction either does not occur or it is nominal in mesencephalic dopamine neurons. The reasons for this lack of compensatory TH mRNA induction remain obscure, because so little is known about the regulation of TH expression in these neurons. In this study, we test whether activation of the cAMP signaling pathway regulates TH gene expression in two rodent models of midbrain dopamine neurons, ventral midbrain organotypic slice cultures and MN9D cells. Our results demonstrate that elevation of cAMP leads to induction of TH protein and TH activity in both model systems; however, TH mRNA levels are not up-regulated by cAMP. The induction of TH protein is the result of a novel post-transcriptional mechanism that activates TH mRNA translation. This translational activation is mediated by sequences within the 3Ј untranslated region (UTR) of TH mRNA. Our results support a model in which cAMP induces or activates trans-factors that interact with the TH mRNA 3ЈUTR to increase TH protein synthesis. An understanding of this novel regulatory mechanism may help to explain the control of TH gene expression and consequently dopamine biosynthesis in midbrain neurons under different physiological and pathological conditions

Comparison of magnetite/reduced graphene oxide nanocomposites and magnetite nanoparticles on enhancing hydrogen production in dark fermentation

Magnetite/reduced graphene oxide nanocomposites (Fe3O4-rGO NCs) and magnetite nanoparticles (Fe3O4 NPs) were added to enhance biohydrogen (bioH(2)) production in dark fermentation. Concentration of supplements from 10 to 100 mg/L was appropriate to enhance bioH(2) production, and inhibition appeared once concentration exceeded 100 mg/L. The best bioH(2) yield was 198.30 mL/g glucose at 100 mg/L Fe3O4 NPs and 225.60 mL/g glucose at 100 mg/L Fe3O4-rGO NCs, which was 42.97% and 62.65% higher than that in the blank group, respectively. Both Fe3O4 NPs and Fe3O4-rGO NCs could intensify butyrate-type fermentation and change the hydrogen-producing microorganism cells morphology, but the enhancement effect of Fe3O4-rGO NCs was superior. Microbial community structure analysis showed that Clostridium-sensu-stricto-1 became more dominant ultimately by Fe3O4-rGO NCs. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Comparison of magnetite/reduced graphene oxide nanocomposites and magnetite nanoparticles on enhancing hydrogen production in dark fermentation

Magnetite/reduced graphene oxide nanocomposites (Fe3O4-rGO NCs) and magnetite nanoparticles (Fe3O4 NPs) were added to enhance biohydrogen (bioH(2)) production in dark fermentation. Concentration of supplements from 10 to 100 mg/L was appropriate to enhance bioH(2) production, and inhibition appeared once concentration exceeded 100 mg/L. The best bioH(2) yield was 198.30 mL/g glucose at 100 mg/L Fe3O4 NPs and 225.60 mL/g glucose at 100 mg/L Fe3O4-rGO NCs, which was 42.97% and 62.65% higher than that in the blank group, respectively. Both Fe3O4 NPs and Fe3O4-rGO NCs could intensify butyrate-type fermentation and change the hydrogen-producing microorganism cells morphology, but the enhancement effect of Fe3O4-rGO NCs was superior. Microbial community structure analysis showed that Clostridium-sensu-stricto-1 became more dominant ultimately by Fe3O4-rGO NCs. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved