A Fast Low-Loss Microstrip p-i-n Phase Shifter

A 4-bit p-i-n phase shifter with low RF attentuation, fast switching time, and low switching power requirements is described. The circuit, made in microstripline, consists of four cells giving phase shifts of 180, 90, 45, and 22.5/sup deg/, respectively. Each cell consists of a 3-dB coupler loaded by two p-i-n diodes. The transmission loss is 1.6 dB /spl plusmn/ 0.2 dB over the operating bandwidth of 11.7-12.2 GHz for a biasing current of only 5 mA/cell. Switching time between phase states is 1 ns.     

A 2-GHz GaAs HBT RF Pulsewidth Modulator

RF pulsewidth modulation (PWM) has been proposed as an efficiency improving technique for power amplifiers (PAs) handling varying envelope signals. The core idea is to modulate the varying envelope into a square-wave signal such that the width of each pulse is varied according to the envelope, and any phase information is contained in the timing of the pulses. The square wave signal can give a theoretical efficiency of 100% for the subsequent PA. Such a system differs significantly from a conventional up-conversion and PA and, therefore, a significant design challenge results. The first important step is to generate the PWM signal. This paper demonstrates a functional modulator for Universal Mobile Telecommunications System operating at 2 GHz. The modulator is designed in a GaAs HBT process and uses low-frequency feedback combined with predistortion to obtain a high spectral purity. Measurements show a Universal Mobile Telecommunications System PWM signal with more than 10-dB margin to the modulation mask and an error vector magnitude of less than 1.5% rms (requirement: 17.5%).     

一种12位开关电流型Σ-△调制器

开关电流电路（ＳＩ）是近年兴起的一种模拟电路。文中引用了新型的两步采样开关电流技术（Ｓ＾２Ｉ）,对该电路中减小时钟馈漏效应的几种方法进行了分析。利用差分平衡结构的Ｓ＾２Ｉ存储单元设计了平衡Ｓ＾２Ｉ积分器,并在此基础上设计出一种平衡差分结构的二阶∑－△调制器。该调制器能够完全与标准ＣＭＯＳ数字工艺兼容。利用标准１．２μｍ数字ＣＯＭＳ工艺的ＨＳＰＩＣＥ模型参数进行了分析,该电路信噪比达到７３．３ｄＢ,     

A 10-GHz Resonant-Type LiNbO 3 Optical Modulator Array

A resonant-type optical modulator array connected with antennas can effectively convert a micro/millimeter-wave to a light wave for the uplink of a radio-on-fiber system. We demonstrated the operation of an array that contained four modulators using power simultaneously received by microstrip antennas connected to each modulator. We confirmed that the optical phase change induced by the received power was proportional to the number of connected antennas     

A 4-GHz Multistage Transistor Amplifier

Multistage microwave transistor amplifiers of simple construction have been developed. In these amplifiers, unit amplifiers of the same design are connected in cascade with short transmission lines inserted between each amplifier. The n-stage (three-, four-, five-, six-, and seven-stage) amplifiers designed for the 4-GHz band gave power gains n times that of the unit amplifier (4 dB) and flat bandwidths of about 1000 MHz. The stripline circuit of the amplifier is fabricated on alumina substrates in the usual way. The amplifier has the disadvantage of poor input and output impedance matching. However, this problem was solved by integrating isolators in the input and output ports of the multistage amplifier. Noise performance of the amplifier is also described.     

A 10-GHz Single Sideband Modulator With 1-kHz Frequency Shift (Correspondence)

A single sideband modulator which frequency shifts a 10-GHz signal by 1 kHz and which suppresses the carrier and unwanted sideband by 65 dB and >57 dB, respectively, with respect to the wanted sideband, is described. The modulator comprises two commercially available double sideband modulators and a readily constructed high-pass filter. Using the modulator in one arm of a microwave bridge, phase shtits and changes in attenuation of <1/spl deg/ and 0.05 dB have been measured; the low modulating frequency allows audio-frequency circuitry to be used to measure the phase shift and attenuation.     

12 GHz枝节匹配宽带微带均衡器

给出了一种匹配良好的宽带微带均衡器的设计。它由在枝节上加载了薄膜电阻的微带枝节谐振器构造而成。通过大量的试验和仿真研究了电阻值对谐振器的影响。当加载薄膜电阻在枝节谐振器上时，可以得到可调的品质因数。利用HFSS分析可以看到电阻加载的枝节谐振器不仅频率可调，而且衰减可调、品质因数可调。文中利用四个加载了不同阻值的枝节谐振器得到了一个12GHz带宽的微带均衡器，给出了结构图和特性曲线。结果表明这种加载电阻的谐振器结构很适合宽带微带均衡器设计。     

A wide-band 4-GHz Esaki-diode injection-locked oscillator

A locking figure of merit larger than 2 was achieved with 4-GHz Esaki-diode oscillators with microstrip-line structure. A typical oscillator gave a locking bandwidth of 720 MHz at a gain of 20 dB.     

A 4-GHz 8-b ADC system

The system described incorporates silicon bipolar, thick-film hybrid, and CMOS process technologies. A sampler chip providing filtered pulses to four analog-to-digital converter chips on one thick-film hybrid can provide 8 b of resolution and a 2-Gsample/s sampling rate. A novel sampling process called sample and filter is used to reduce the bandwidth requirements of post-sampling circuitry. Two thick-film hybrids with interleaved sample timing were used to obtain a 4-Gsample/s sample rate, 2-GHz bandwidth, and eight effective bits at DC. The goals for system functionality, resolution, bandwidth, and noise were all met with the initial prototypes of the chips and the thick-film hybrid     

A Low-Cost Multiple-Channel 12-GHz Receiver for Satellite Television Broadcasting

The design of a low-cost FM-microwave satellite-ground-station receiver is described. It is capable of accepting 12 contiguous color-television equivalent-bandwidth channels in the 11.72-12.2-GHz band using a wide-band FM format and frequency division multiplexing (FDM) of the channels. Each channel has 36 MHz of usable bandwidth with a 4-MHz guard band and provides a CATV compatible output. The overall system specifications are first discussed. Then consideration is given to the design, fabrication, and evaluation of the different subsystems in the receiver.     

A Compact 4-GHz Linearize for Space Use

A compact and lightweight 4-GHz linearizer for satellite TWTA's has been developed by using MIC packages with chip devices. The linearize is composed of a preamplifier, a predistortion Iinearizer, and a limiting ampfifier, consisting of two, three, and three 25x12.5-mm packages, respectively. It improves the noise power ratio for an FM system by 3 dB and the required C/N for a TDMA system by 4.5 dB compared with the conventional satellite TWTA. A space environmental test and an aging test were successfully performed on the equipment.     

A Novel Bidirectional 60-GHz Radio-Over-Fiber Scheme With Multiband Signal Generation Using a Single Intensity Modulator

We experimentally demonstrated a novel radio-over-fiber system to simultaneously generate dispersion-tolerant multiband downstream signals, including millimeter-wave, microwave, and baseband signals, based on multicarrier modulation in an intensity modulator and a subsequent optical filter. The uplink connection is realized by remodulation of downlink optical carrier and by baseband detection in the central office. The high-dispersion tolerance comes from the subcarrier cross-selection with only one data-bearing tone before signal beating in the receiver. The power penalty of 1.4 dB for 60-GHz carrier and negligible degradation for baseband and upstream are achieved for 2.5-Gb/s signal after 50-km single-mode fiber (SMF-28) and 4-m air link transmission. The theoretical analysis is also provided to obtain the optimal operation point.     

A New Six-Port Transformer Modeling Methodology Applied to 10-dBm 60-GHz CMOS ASK Modulator Designs

This paper presents a new broadband equivalent-circuit model for millimeter-wave transformers on silicon. The model includes a center tap on the primary and secondary, and considers coupling between all segments of the windings. A corresponding methodology to analytically extract the model from electromagnetic (EM) simulations is developed. The broadband model is verified by EM simulations and measurements. Two amplitude modulatable power oscillators with high power efficiency are demonstrated using low-loss transformers. One achieves an output power of 10.4 dBm near 57 GHz with a total efficiency of 23.6%. Applying amplitude-shift keying modulation, their maximum data rate exceeds 2 Gb/s. Simulations of these circuits showed the transformer model performs well in time-domain simulations.      

一种带匹配路径约束的最长公共子序列长度算法

在带约束的最长公共子序列问题中提出一种特殊的新问题：假设有两序列Q和C, Q中指定的匹配位置序列I,计算两序列Q和C的最长公共子序列,且这个最长公共子序列的匹配路径必须经过位置序列I。针对此问题,该文提出一种带匹配路径约束的最长公共子序列算法。首先定义带匹配路径约束的最长公共子序列模型,其次推出该序列的性质,最后求出带匹配路径约束的最长公共子序列长度的基础算法和快速算法。基础算法和快速算法时间复杂度分别为O(mnt)和O(mn), m, n, t分别为序列Q, C, I的长度。     

A 12-GHz silicon bipolar dual-conversion receiver for digital satellite applications

A 12-GHz monolithic silicon bipolar receiver for digital video broadcasting via satellite (DVB-S) is presented. The receiver is based on a dual-conversion superheterodyne architecture that employs a single LO integrated in the same die. To comply with the stringent LO phase noise requirement of -101 dBc/Hz at 100 kHz offset from the carrier, an innovative VCO topology, based on a three-layer monolithic transformer, was used. The VCO exhibits a phase noise of -102 dBc/Hz at 100 kHz offset from a 5.3-GHz carrier and a 1.1-GHz tuning range. At 12 GHz, the conversion gain is 33.6 dB, the single-sideband noise figure is 5.9 dB and the output IP3 is +16 dBm. This work reports the first 12-GHz DVB-S monolithic receiver integrated in a low-cost silicon bipolar technology.     

A 46-GHz Direct Wide Modulation Bandwidth ASK Modulator in 0.13-μm CMOS Technology

A 46-GHz direct wide modulation bandwidth amplitude shift keying (ASK) modulator with an embedded voltage controlled oscillator (VCO) is proposed in this letter. This circuit is fabricated using a standard commercial bulk 0.13-mum CMOS technology and exhibits a modulation bandwidth wider than 1 GHz with a chip size of 390 times 480 mum². The recovered time-domain waveform shows a very good eye-pattern opening. To the best of the authors' knowledge, this is the first direct ASK modulator with an embedded VCO in the millimeter-wave regime using CMOS processes.     

A Wide-Band 12-GHz 12-Way Planar Power Divider/Combiner (Short Paper)

A 12-way, low-loss, wide-band planar electrically symmetric hybrid power divider/combiner for the X-band is described. It is a two-stage fork, 12-way hybrid realized completely in microstrip. A circuit design is given to maximize the match and isolation at band center. Over a frequency band of 10-13 GHz, this divider/combiner has an insertion loss of less than 1 dB and an isolation between output ports of better than 17 dB.     

中部开周期性缝隙的微带漏波天线及其在微带漏波天线小型化中的应用

传统的微带漏波天线在长度较短的情况下性能较差,主要表现为反向波束较大。1979年由W．Menzel首先提出的微带漏波天线长为10cm（2．23λ0）,为获得更好的性能,天线的长度要增大到4至5个波长。增大天线的长度可以改善天线的性能,但会影响到它在很多领域的应用。当微带漏波天线的中部开周期性的缝隙后,天线表面的电流分布会改变,天线的性能将随之改变。分析了周期性缝隙的各个参数对微带漏波天线主波束方向角和主波束增益的影响,以及这种方法在微带漏波天线小型化中的应用。     

A 4-GHz Lumped-Element Circulator (Short Papers)

The successful application of thin-film lumped-element circulators (LEC) at L band has led to the following question: How far can these devices be extended in frequency using our present beam-crossover technology? An exploratory study aimed at building an LEC at approximately 4 GHz was successfully completed. Preliminary tests showed a 20-dB band from 4.2 to 5 GHz with an insertion loss <1 dB (minimum, 0.5 dB). This includes fixture losses, which account for about 0.2 dB. The device has been tuned to operate above 5 GHz, and from the experiments it is concluded that a device of this type could be built at frequencies as high as X band. These devices are very small; at 4 GHz, the circulator junction is a 0.075- in diam.     

A 12–18-GHz Three-Pole RF MEMS Tunable Filter

This paper presents a state-of-the-art RF microelectromechanical systems (MEMS) wide-band tunable filter designed for the 12–18-GHz frequency range. The coplanar-waveguide filter, fabricated on a glass substrate using loaded resonators with RF MEMS capacitive switches, results in a tuning range of 40% with very fine resolution, and return loss better than 10 dB for the whole tuning range. The relative bandwidth of the filter is$hbox5.7pm hbox0.4hbox%$over the tuning range and the size of the filter is 8 mm$, times ,4$mm. The insertion loss is 5.5 and 8.2 dB at 17.8 and 12.2 GHz, respectively, for a 2-$hboxkOmega/hboxsq$bias line. The loss improves to 4.5 and 6.8 dB at 17.8 and 12.2 GHz, respectively, if the bias line resistance is increased to 20$hboxkOmega/hboxsq$. The measured$ IIP_3$level is$≫$37 dBm for$Delta f ≫ 200$kHz. To our knowledge, this is the widest band planar tunable filter to date.