Design and analysis of a CMOS passive Σ∆ ADC for low power RF transceivers

Design and analysis of a Σ∆ modulator with a passive switched capacitor loop filter is presented. Design steps for optimum loop filter design for quantization noise suppression and thermal noise reduction is outlined. Design specifications for sampling clock phase noise, reference buffer and input buffer settling is analyzed. Presented design has a 2nd-order loop filter and uses only metal-metal capacitors and thin oxide digital transistors with no additional components occupying less than 0.1 mm² silicon area in 0.13 μm CMOS digital process. Measurement results show that the ADC achieves 80 dB peak SNR at a 100 kHz integration bandwidth with 1 pJ/sample conversion efficiency. With decimation filter power consumption of 0.22 mW at 104 MHz sampling rate, the ADC consumes only about 1 mA at 1.5 V for each channel.     

Aluminum nitride for heatspreading in RF IC’s

To reduce the electrothermal instabilities in silicon-on-glass high-frequency bipolar devices, the integration of thin-film aluminum nitride as a heatspreader is studied. The AlN is deposited by reactive sputtering and this material is shown to fulfill all the requirements for actively draining heat from RF IC’s, i.e., it has good process compatibility, sufficiently high thermal conductivity and good electrical isolation also at high frequencies. The residual stress and the piezoelectric character of the material, both of which can be detrimental for the present application, are minimized by a suitable choice of deposition conditions including variable biasing of the substrate in a multistep deposition cycle. Films of AlN as thick as 4 μm are successfully integrated in RF silicon-on-glass bipolar junction transistors that display a reduction of more than 70% in the value of the thermal resistance.     

Thyristor Input-Protection Device Suitable for CMOS RF IC’s

Based on simulation results and accompanying analysis, we suggest a thyristor-type ESD protection device structure suitable for implementation in standard CMOS processes to reduce the parasitic capacitances added to the input nodes, which is very important in CMOS RF ICs. We compare DC breakdown characteristics of the suggested device to those of a conventional NMOS protection device to show the benefits of using the suggested device for ESD protection. The characteristic improvements are demonstrated and the corresponding mechanisms are explained based on simulations. Structure dependencies are also examined to define the optimal structure. AC simulation results are introduced to estimate the magnitude of reduction in the added parasitic capacitance when using the suggested device for ESD protection. The analysis shows a possibility of reducing the added parasitic capacitance down to about 1/45 of that resulting with a conventional NMOS protection transistor, while maintaining robustness against ESD.Jin-Young Choi was born in Seoul, Korea in 1956. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the M.S. and Ph.D. degrees in electrical engineering from the University of Florida, USA, in 1986 and 1991, respectively. In 1991, he joined Samsung Electronics Memory Division, Korea, where he was engaged in high-speed SRAM development. In 1992, he moved to the Hongik University, Jochiwon, Korea, where he is now an associate professor. His recent research interests include the high-frequency modeling of CMOS devices, CMOS RF circuit design, and analysis & design for ESD protection.Woo Suk Yang was born in Seoul, Korea in 1957. He received the B.S. degree in electrical engineering from the Seoul National University, Korea, in 1979, and the Ph.D. degree in electrical and computer engineering from the North Calorina State University, USA, in 1990. His doctorial research was in the area of signal processing. In 1990, he joined LG Electronics Co. Korea. In 1991, he moved to the Hongik University, Jochiwon, Korea, where he is now a professor. His recent research interests include the high-frequency modeling and various topics in signal processing area.Dongmin Kim was born in Korea in 1956. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea, in 1979 and 1984, respectively and the Ph.D. degree in ECE from the University of Michigan, USA, in 1996. Now, he is an assistant professor of the Hongik University, Jochiwon, Korea. His recent research interests include circuit design and analysis.Youngju Kim was born in Seoul, Korea in 1957. He received the B.S. and M.S. degrees in electrical engineering from the Seoul National University, Korea in 1980 and 1985, respectively and the Ph.D. degree in electrical engineering from the Polytechnic University of New York, USA, in 1995, respectively. In 1996, he joined the Hongik University, Jochiwon, Korea, where he is now an assistance professor. His recent research interests include the RF circuit design and LIN wireless systems.     

RF IC收发器的建模

便携通信产品(如寻呼机、双向无线收发机、无绳电话、蜂窝电话、个人全球定位系统(GPS)接收机,无线Internet浏览器和便携可视电话等)的全球市场正在日益增长.这些小型无线手机可传送语音、数据、图像和视频,这将导致人们通信和存取信息方法的革命.这些高性能通信系统的制造商必须在产品的功耗、成本、尺寸、重量和性能诸方面进行激烈的竞争.RF收发器是关键的硬件,它决定一种便携手持通信产品的性能、成本、大小及电池寿命.然而,没有适当的工具实现RF收发器的设计和验证是困难的或者是不可能的.     

移动电话用RF IC的最新进展

就移动电话而言，小型、轻量、低功耗、低成本以及较短的开发周期都是基本而又迫切的要求。在各器件中，RFIC对增强产品的竞争力起着非常重要的作用。本文着重介绍国外主要的RF半导体厂商在这方面的最新进展。     

RF IC芯片的测试挑战

目前专注在RF的厂商不在少数,但特别专注在RFTesting技术上的却不多,LTX即是其中之一。     

Systematic top-down design of reconfigurable ΣΔ modulators for multi-standard transceivers

This paper addresses the design techniques of reconfigurable analog-to-digital converters for multi-standard wireless communication terminals. While most multi-standard converters reported so far follow an ad hoc design approach, which do not guarantee either efficient silicon area occupation or power efficiency in the different operation modes, the methodology presented here formulates a systematic design flow that ensures that both factors are considered at all hierarchical levels. Expandible cascade modulators are considered as the starting point to further reconfigurability at the architectural level. From here on, and using a combination of accurate behavioral modeling, statistical optimization techniques, and device-level simulation, the proposed methodology handles the design complexity of a reconfigurable converter while ensuring adaptive power consumption and boosting hardware sharing. A case study is presented where a reconfigurable modulator is designed to operate under three communication standards, GSM, Bluetooth, and UMTS, in a 130 nm-CMOS technology.     

RF功率放大器IC在移动电话中的应用

目前已进入“无线时代10年”的后半期,在移动电话中靠近天线部分巳使用单片IC,这正是技术人员和企业家所期盼的。     

实现即插即用的RF前端IC亮相

成立才一年半的RFaxis公司,藉今年的COMPUTEX向厂商介绍号称业界最小且最高整合度的RF前端IC,用以取代现行体积较大的IRF前端模块,此次最先推出的两款芯片,可支持Bluetooth、Zigbee、WLAN和MIMO等主流无线技术,未来将会推出支持WiMAX和WHDI的芯片。     

RF IC技术的若干发展动向

RFIC(射频集成电路)是90年代中期以来随着IC工艺改进而出现的一种新型器件.RFIC的技术基础主要包括:1)工作频率更高、尺寸更小的新器件研究;2)专用高频、高速电路设计技术;3)专用测试技术;4)高频封装技术.本文将从IC技术的角度对该领域近期出现的一些新动向进行简要的综述和分析.     

PM88xx：WiMAX RF IC

PMC-Sierro宣布用于宽带无线用户设备的高集成度WIMAX RF IC方案—WiZIRD系列又新增四个多频段器件，新器件可使WiMAX系统设计人员用一个射频设计为全球WiMAX部署所有常用宽带无线频段（450-928MHz、2.3-2.7GHz、2.7-2.9GHz、3.3-3.8GHz以及4.9-5.95GHz）提供用户终端设备（CPE）和网络接口卡（NIC）。     

RF振荡电路用IC—MAX2620

MAXIM公司生产的MAX2620是一种可在10MHz～1050MHz频率范围内使用的振荡电路用IC。该IC内藏直流电源和输出缓冲器,能够在温度和负载发生变化的情况下实现稳定的振荡。其功耗较小(Vcc=3V时为27mW),适用于以电池为能源的便携式设备。     

集成微控制器和发送器的RF IC

ATA6285和ATA6286是带有传感器接口的微控制器和发送器IC，可用于轮胎安全监测系统中。它们在睡眠模式下的最低电流为0．5mA，在95℃、90kHZ的振荡模式下的最大电流为0．85mA，在传感器测量时的电流为200mA，在传输模式、6dBm下的电流为8．5mA。     

Time‐varying modeling of a nonstationary signal

In this paper, a method for modeling a nonstationary signal using timevarying parameters by considering that the signal is generated by a linear, timevarying (LTV) system with a stationary white noise input is presented. This method is based on the Wold–Cramer (WC) representation of a nonstationary signal. Because the relationship between the generalized transfer function of an LTV system and the timevarying coefficients of the difference equation of a discretetime system is not addressed so far in the literature, therefore, in this paper a solution to this problem is proposed. A simple relationship between the system generalized transfer function and the timevarying parameters of the system is derived, then an MLS algorithm is developed to solve for the system timevarying parameters. Computer simulation illustrating the effectiveness of our algorithm is presented.     

Adaptive Threshold Median Filter for Multiple-Impulse Noise

Attenuating the noises plays an essential role in the image processing. Almost all the traditional median filters concern the removal of impulse noise having a single layer, whose noise gray level value is constant. In this paper, a new adaptive median filter is proposed to handle those images corrupted not only by single layer noise. The adaptive threshold median filter （ATMF） has been developed by combining the adaptive median filter （AMF） and two dynamic thresholds. Because of the dynamic threshold being used, the ATMF is able to balance the removal of the multiple-impulse noise and the quality of image. Comparison of the proposed method with traditional median filters is provided. Some visual examples are given to demonstrate the performance of the proposed filter.     

PMC—Sierra扩展WiMAX RF IC方案

PMC—Sierra为宽带无线高集成WiMAX RF IC方案的WiZIRD系列新增4个多频段器件,该产品可使系统设计人员用一个射频为全球WiMA×部署常用宽带无线频段（450～928MHZ、2．3～2．7GHZ、27～29GHZ、3．3～3．8GHZ以及49～5．95GHZ）,提供用户终端设备和网络接口卡。WiZIRD系列是业界应用广泛且完整的WiMAX RF IC产品,在成本和性能上具有很高的灵活性,可应对全球各地不同频谱带来的挑战。     

Silicon Labs CMOS产品抢占RF IC市场

Silicon Laboratories是目前业界唯一用CMOS工艺量产RFIC的厂商,GSM/GPRS手机IC的市场份额两年内增长了20%。公司最近发布了业界第一颗利用标准数字CMOS工艺生产的GSM功率放大器。与多芯片和分立器件组成的典型功率放大器模块相比,Si4300为单芯片PA,前者至少需要1个HV-CMOS内核、2个GaAsHBT内核,以及5个分立器件,基底面积约为70mm2, 后者为单一的标准CMOS芯核,不需要分立器件,基底面积为25mm2。Si4300集成了收发器到天线开关模块间的所有功能,包括完整的功率控制电路、过热和负载不匹配保护功能、谐波滤除以及输入和输出…     

直接变频RF IC不需要SAW滤波器

随着含较高性能与功能的小型器件需求的不断增加,芯片数需要减少。ＡＤ公司用于ＧＳＭ／ＧＰＲＳ蜂窝电话和无线Ｉｎｔｅｒｎｅｔ设备的下一代ＲＦＩＣ芯片集,通过去掉ＳＡＷ ＩＦ滤波器,把ＲＦ功能高度集成在一个芯片上,可以减少芯片数。 ＡＤ公司的新型直接变频收发器ＩＣ把其第一代双芯片Ｏｔｈｅｌｌｏ的所有功能都集成在了一个芯片上。三频段ＧＳＭ芯片Ｏｔｈｅｌｌｏ Ｏｎｅ共有５１个元件,比上一代产品少了４０％。新型芯片集成有ＲＦ收发器、多频段Ｎ分频锁相环合成器、三个ＧＳＭ频段的ＬＮＡ, Ｒ Ｆ功率控制器以及ＬＤＯ稳…     

基于CMOS的RF IC的发展现状

目前，射频电路存在广阔的市场，成为无线通信领域内研究的热点之一。文章主要介绍了基于CMOS工艺的射频电路的研完现状。