Direct-conversion radio transceivers for digital communications

Direct-conversion is an alternative wireless receiver architecture to the well-established superheterodyne, particularly for highly integrated, low-power terminals. Its fundamental advantage is that the received signal is amplified and filtered at baseband rather than at some high intermediate frequency. This means lower current drain in the amplifiers and active filters and a simpler task of image-rejection. There is considerable interest to use it in digital cellular telephones and miniature radio messaging systems. This paper briefly covers case studies in the use of direct-conversion receivers and transmitters and summarizes some of the key problems in their implementations. Solutions to these problems arise not only from more appropriate circuit design but also from exploiting system characteristics, such as the modulation format in the system. Baseband digital signal processing must be coupled to the analog front-end to make direct-conversion transceivers a practical reality     

CMOS mm-wave transceivers for Gbps wireless communication

The challenges in the design of CMOS millimeter-wave (mm-wave) transceiver for Gbps wireless communication are discussed. To support the Gbps data rate, the link bandwidth of the receiver/transmitter must be wide enough, which puts a lot of pressure on the mm-wave front-end as well as on the baseband circuit. This paper discusses the effects of the limited link bandwidth on the transceiver system performance and overviews the bandwidth expansion techniques for mm-wave amplifiers and IF programmable gain amplifier. Furthermore, dual-mode power amplifier (PA) and self-healing technique are introduced to improve the PA''s average efficiency and to deal with the process, voltage, and temperature variation issue, respectively. Several fully-integrated CMOS mm-wave transceivers are also presented to give a short overview on the state-of-the-art mm-wave transceivers.     

High speed serial transceivers for data communication systems

The architecture and critical circuit design issues for high-speed serial data links operating in excess of 1 Gb/s are described. Trade-offs in power vs. performance are presented for SONET/SDH transceivers and backplane transceivers for Infiniband or similar standards     

A wideband SAW resonator and its application to a VCO for mobileradio transceivers

A new wideband SAW resonator has been developed for SAW-VCOs used in mobile radio communication transceivers. The resonator is based on a repeated structure of pairs of electrically connected IDTs, which provides a high Q and a wide frequency bandwidth. An experimental SAW-VCO module measuring 8×8 mm² offers a frequency-variation bandwidth of about 20 MHz, a C/N of 75 dB, and an output power of 3-4 dBm at 900 MHz, satisfying the specifications for Japanese MCA and business-use radio transceivers     

一种用于LoRa可穿戴设备的小型化双频段天线

提出了一种适用于LoRa可穿戴设备的小型化双频段天线.该天线由半径为18 mm的基板及上方高6 mm的圆环支架构成，利用顺时环绕单极子、耦合分支在一定小型化的结构上激励出两个低频谐振模式，满足LoRa天线性能要求.实测天线-10 dB阻抗带宽为476~502 MHz和854~879 MHz，能够覆盖LoRa设备在470~510 MHz和863~868 MHz的大部分工作频段，同时在490 MHz和865 MHz两个工作频率点测得效率分别为15.56%和27.91%.该天线结构简单，覆盖频率广，体积小，工作频带内具有良好的辐射性能，具有一定的工程应用价值.     

Strain effects in SAW devices

An analytical model is developed to determine the velocity of surface acoustic waves in strained media. It is shown that, in addition to the variations in path length, the SAW propagation may depend significantly on the velocity change with strain.     

不同光纤收发器间（QSFP与GTH）通信研究与实现

本文介绍了Xilinx Virtex-6 HXT系列FPGA内嵌光收发器GTH与Tyco Electronics光收发器QSFP,实现了光纤数据的高速传输。     

小型化双通带声表滤波器设计研究

针对小型化双通带声表面波(SAW)滤波器的需求背景,对两端口、两通带的SAW滤波器的设计技术展开研究。通过搭建包含两组耦合模(COM)参数的双通带SAW滤波器声电协同仿真平台,分析优化滤波器性能,成功研制出CSP2520封装的双通带SAW滤波器,其中心频率分别为1 995 MHz和2 185 MHz,通带带宽均为40 MHz,插入损耗小于3 dB,通带间隔离度大于30 dB。测试与仿真结果基本一致。     

Spurious acoustic responses in SAW devices

Substantial documentation of the character of spurious responses in SAW devices has shown that they can be completely characterized as families of plate modes when the substrates have parallel top and bottom surfaces. Presented here are theoretical plate mode calculations and the corresponding experimental results for commonly used substrate orientations. It is shown that quantitative terminal response predictions are possible when all the plate modes are included in the analysis. Results for a new substrate cut, 46° (ZYW) LiNbO3, show that it can have lower than -60-dB spurious modes relative to the Rayleigh mode.     

SAW器件用金刚石膜的制备工艺研究

针对声表面波( SAW)器件对金刚石膜的要求,采用石英钟罩式微波等离子体化学气相沉积(MPCVD)装置,研究了不同气体体系对金刚石膜生长速率、电阻率、表面形貌、表层C化合态及相对含量(粒子数分数Xc)的影响.结果表明:在H2-CH3COCH3、CH4-H2-Ar和CH4-H2-N2三种气体体系下,金刚石膜的生长速率分别...     

Probability distributions for the number of radio transceivers which can communicate with one another

This paper considers points which can communicate with one another and which are uniformly and randomly distributed on the plane, assuming an inverse power law for attenuation and log-normal shadowing. First, a probability distribution is obtained for the distance between a pair of such points. Communication is assumed to be possible if the attenuation of a signal transmitted from one point, say a mobile phone, does not exceed some specified value by the time it reaches the other, say a base station. The probability distribution of the number of base stations which can hear such a signal from a given mobile is found. An example shows how the probability that a mobile is in a handover region between two or more base stations can be evaluated. The analysis is extended to the case where the power law changes at a specified distance from the mobile, and also to consider the effect of an area within the plane containing a greater density of mobiles and/or base stations (a hot spot). A final result gives the conditional distribution for the number of base stations within some specified area of the plane, given the number within some larger area containing that specified area. The results also apply to the number of mobiles within range of a base station and, in an ad hoc network, to the number of nodes within range of a given node.     

Design of high-speed data transfer turbo code for body channel communication transceivers

In this work, a digital differential transmitter based on low-power wireless compensation transceiver for body channel communication (BCC) is proposed. Further, the proposed transceiver is composed of Touch Status Detection Unit (TSDU), Wireless Status Compensation Unit (WSCU), and a reconfigurable preamplifier. Initially, the human body channel environment for wireless communication is investigated based on properties from 1 to 100 MHz. Further, the turbo code-based encoding scheme is used to encode the data before transferring the data on the transmitter side. Also, the proposed error-correcting parallel turbo decoder using a modified step-by-step algorithm is presented. The turbo code-based decoding scheme is used to recover the error-free transmitted data at the receiver side. Results demonstrate that the proposed BCC transceiver is designed using 90 nm CMOS technology and it is observed that the proposed BCC transceiver has utilized an area of 600mm². Also, the maximum data rate achieved by a proposed BCC transceiver was 100 Mbps, and the overall transceiver power consumption is 0.42 mW, and energy for communication is 0.02 nj/b.     

Transoceanic radio communication

The paper defines the state of the art of today which is the result of developments during the war. Transatlantic radio communication is at present maintained by five first class stations, two in America and three in Europe. These stations operate at wave lengths between 12,500 and 17,000 meters. The range of wave lengths suited for such traffic is rather limited, the desirable wave length being included between the limits of 10,000 to 20,000 meters. New developments indicate three methods for increasing the radio traffic without interference between the different messages. These methods are increase of the transmitting speed, closer spacing of wave lengths and directive reception. If these technical possibilities are intelligently used, the author predicts that radio communication will be equal to all demands that will be placed upon it. The second part of the paper describes the radio transmitting system for the development of which the author is responsible. This system is represented by the naval radio station, New Brunswick, N. J. and comprises new means for generating modulating, and radiating the continuous wave energy. The generator is the high-frequency alternator with which the author's name has become associated. The modulating system is the "magnetic amplifier" which is described in a paper by the author before the Institute of Radio Engineers. The "multiple antenna" system of radiation is described in this paper for the first time. The general theory and figures for the increased radiation efficiency are given. The author also predicts that the multiple antenna will make possible directive radiation on a large scale.     

New radio networks for tactical communication

A packet-switched radio system designed and developed for the Norwegian Army is presented. In particular, the development of an overall network concept, the network and access protocols, and the routing strategy are examined. Network synchronization and radio process protocols are discussed, and simulation results are given. A radio design allowing integration of electronic countermeasures (ECM) protected data and voice channels is presented     

Guided-wave devices for optical communication

We review the current status of guided-wave optical communication devices. The operation and presently demonstrated performance characteristics of waveguides switches, modulators, filters, and polarization transforming devices are discussed. Emphasis is given to recent developments with very high speed modulators and polarization insensitive devices.     

Quantification of electromagnetic absorption in humans from body-mounted communication transceivers

The internal electric (E) field and energy deposition in a full-size adult male mannequin in the immediate vicinity of 1.5 W body-mounted communication transceivers have been measured. Transceivers operating at the four frequencies 50, 150, 450, and 800 MHz, and placed at various locations vis-à-vis the body were used. The mannequin was filled with two-thirds muscle-simulant biological phantom mixtures at each of the four frequencies. The complex permittivities (ε^*) of these mixtures were confirmed by measurement. The internal E-field distribution was measured by three-dimensional implantable E-field probes. Relatively superficial energy depositions were obtained at points close to the location of the transceiver antenna for the two higher frequencies with energy depositions typically less than 1-2 W/kg. Considerably reduced energy depositions were measured at the two lower frequencies on account of in-depth and wider dissemination of the absorbed energy and the relatively high ε^*of the tissues which results in an increased shielding of the body.     

Spurious response sensitivity of two-way transceivers related to the 3rd-order nonlinearity of SAW filters

The spurious response sensitivities (SRSs) of two-way radio transceivers, as determined from the 3rd-order nonlinearities of SAW filters, are compared using two types of filter, the IIDT-type and a newly-developed SAW-resonator-coupled type, in high-power ( approximately 1 W) applications. The latter type is shown to result in an SRS which satisfies system specifications with sufficient margins.<>     

Mobile in-home UHF radio propagation for short-range devices

In-home propagation measurements, in the frequency range of 400, 860, and 2400 MHz, are evaluated for single, narrow-band applications of one-way domestic mobile alarm systems. In particular, the influence of multipath effects is investigated     

Display technologies for portable communication devices

Telecommunications networks are rapidly advancing toward adequate capacity to support multimedia content transmission between mobile terminals. This development opens opportunities for terminal manufacturers to realize functions on the devices that previously have been considered impractical. It is necessary for the terminals, however to exploit advances in new display technologies, such as reflective-color liquid-crystal displays, bistable displays, organic emissive displays, and microdisplays, to make use of the new functionality. The state of the art of mobile phone and personal digital assistant displays as well as some of the emerging technologies are reviewed based on their applicability in new uses in mobile terminals