Broadband radio access: LTE and LTE-advanced

Sawahashi, Mamoru; Kishiyama, Yoshihisa; Taoka, Hidekazu; Tanno, Motohiro; Nakamura, Takehiro

doi:10.1109/ispacs.2009.5383862

Cited by 15 publications

(8 citation statements)

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“…As a result, telecommunications systems such as Global System for Mobile (GSM) or Code Division Multiple Access (CDMA) have been partially replaced by networks that allow higher data transfer rates and multiple users per band. One such technology is the Long Term Evolution (LTE) system [1], characterized by broadband data transfer through multiple narrow bandwidth subcarriers. Multiple LTE frequency bands have been released in the ultra-high-frequency range.…”

Section: Imentioning

confidence: 99%

L-band Lamb mode resonators in Gallium Nitride MMIC technology

Popa

Weinstein

2014

2014 IEEE International Frequency Control Symposium (FCS)

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We present a theoretical and experimental study of L-band (1-2 GHz) Lamb mode resonators in Gallium Nitride (GaN) monolithic microwave IC technology. These resonators leverage Au-free metallization and optimized anchors, enabling f·Q products up to 5.5×10 12 , the highest reported in GaN resonators to date. These devices also demonstrate the highest electromechanical coupling (keff 2 of 0.39%) measured in GaN resonators using an interdigitated transducer in the absence of a bottom electrode. Achieving such high values of f·Q and keff 2 , these GaN MEMS resonators can enable channel select filters for wireless communications, with wide bandwidth tuning capabilities (0.18 -0.8 MHz ) at 1-2 GHz range.Keywords-gallium nitride, III-V, piezoelectricity, MEMS resonators, Lamb mode resonator. I.MOTIVATION Over the past few years, the transition to third and fourth generation (3G, 4G) wireless communications has led to an increase in demand for higher bandwidth wireless data transfer with unprecedented frequency selectivity. As a result, telecommunications systems such as Global System for Mobile (GSM) or Code Division Multiple Access (CDMA) have been partially replaced by networks that allow higher data transfer rates and multiple users per band. One such technology is the Long Term Evolution (LTE) system [1], characterized by broadband data transfer through multiple narrow bandwidth subcarriers. Multiple LTE frequency bands have been released in the ultra-high-frequency range. In order to achieve cost-efficient data transfer rates, these LTE radio access networks can benefit from efficient hardware, including both front-end filters and reliable frequency sources for clocking. With quality factors exceeding 5,000 at GHz frequencies, small footprints, and the ability to achieve multiple frequencies on the same chip, MEMS resonators can provide solutions for low loss narrow bandwidth filters and low phase-noise oscillators for operation over a wide frequency range.MEMS resonators also have the capacity for monolithic integration with standard integrated circuits, which has the benefit of reduced size, weight, and power, improved parasitics, and reduced impedance matching constraints, particularly at high frequencies. A lot of effort has gone into CMOS integration of MEMS resonators [2,3]. However, for high power, high frequency applications, III-V monolithic microwave ICs (MMICs) are increasingly dominating the market. As a wide bandgap semiconductor, GaN provides high electron velocities, charge densities (1×10 13 cm -2 in AlGaN/GaN), and critical electric fields, ideal for high power (>10W/mm), high frequency (>300 GHz) ICs. GaN also exhibits high piezoelectric coefficients (electromechanical coupling keff 2 up to 2% in FBARs) while at the same time having high acoustic velocities and low acoustic losses.The authors have previously demonstrated high performance passive and active (HEMT-sensed) GaN resonators from 200 MHz to 3.5 GHz in both flexural and contour modes [4]. Successful implementation of MEMS resonators for c...

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Section: Imentioning

confidence: 99%

L-band Lamb mode resonators in Gallium Nitride MMIC technology

Popa

Weinstein

2014

2014 IEEE International Frequency Control Symposium (FCS)

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“…Table 1 shows the typical ADC specifications for some of the most widespread mobile communication (LTE/LTE-Advanced [14][15][16]) and wireless connectivity standards (WiFi [3,17]). …”

Section: Requirements For Adcs Used In Communication Systemsmentioning

confidence: 99%

“…15 This is not critical in communication systems. Similarly, the input gain factor of the second stage, (i.e.…”

Section: N1mentioning

confidence: 99%

“…Using (2) to calculate the output of the DAC, and then considering the subtraction and residue amplification, leads to the input voltage of the backend ADC Fig. 23 Gain error modeling in the first stage of a N 1 + N bck -1 bit pipeline ADC 15 The quantizer is not affected by this gain error. From the perspective of the MDAC it is as if the code transition voltages of the quantizer are shifted, but this is not a problem due to redundancy.…”

Section: N1mentioning

confidence: 99%

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Recent Advances and Trends in High-Performance Embedded Data Converters

Figueiredo¹

2014

High-Performance AD and DA Converters, IC Design in Scaled Technologies, and Time-Domain Signal Processing

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This chapter discusses the architectures of Nyquist rate Analog-toDigital Converters (ADCs), that are embedded in systems-on-chip (SoCs) implementing some of the most widespread mobile communication, wireless and wireline connectivity standards. The typical requirements for these ADCs are presented, and the main conversion architectures are described in terms of the fundamental operations realized inside them. This constitutes a unified treatment that relates all architectures, thus providing a deeper understanding of their fundamental limitations and trade-offs. We then discuss some of the solutions recently published in the literature to improve ADC energy efficiency. Finally we disclose implementation details from two 12 bit digitally calibrated, high-speed ADCs, using the pipeline and SAR architectures.

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“…Thus, a set of user equipment (UE) for LTE-Advanced must be able to access Release 8 LTE networks, and LTE-Advanced networks must be able to support Release 8 LTE UEs. Third, LTEAdvanced should meet or exceed the IMT-Advanced minimum requirements within the ITU-R time plan [6].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Frequency Diversity Exploitation in Carrier Aggregation for LTE-Advanced Systems

Qiu

Minn

Chong³

2011

2011 IEEE Vehicular Technology Conference (VTC Fall)

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Abstract-LTE-Advanced systems have adopted the concept of Carrier Aggregation (CA) to meet the data rate requirements of IMT-Advanced systems. The CA approach opens up several new implementation challenges as well as opportunities for further performance improvement. Existing works on CA focus on implementation issues, but exploitation of CA-specific features for performance improvement has not been addressed yet. In this paper, we fill this gap and investigate the enhanced frequency diversity exploitation in CA based systems. New interleaving schemes for both downlink OFDMA and uplink SC-FDMA of LTE-Advanced systems are proposed to capture CA-specific enhanced frequency diversity with simple implementation. The proposed schemes also provide full backward compatibility with the LTE system. Performance evaluation via simulation in a simplified LTE system environment corroborates that the proposed approach provides performance advantages in both downlink and uplink.

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Broadband radio access: LTE and LTE-advanced

Cited by 15 publications

References 1 publication

L-band Lamb mode resonators in Gallium Nitride MMIC technology

L-band Lamb mode resonators in Gallium Nitride MMIC technology

Recent Advances and Trends in High-Performance Embedded Data Converters

Enhanced Frequency Diversity Exploitation in Carrier Aggregation for LTE-Advanced Systems

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