Laser Stabilization on a Fiber Ring Resonator and Application to RF Filtering

The potential of optical fiber ring resonators for radio frequency (RF) or microwave signals filtering on optical carriers is demonstrated on a short length high Q resonator. The problem of the frequency shift due to the resonator self heating with the optical power is solved thanks to a Pound-Drever feedback loop. A multifrequency RF filter is obtained, with a frequency step of 205 MHz between resonances, and a 3-dB bandwidth of 2.4 MHz. This corresponds to the computed optical resonator 3-dB bandwidth, and thus represents an efficient technique for the measurement of ultrahigh Q optical resonators. In the field of microwave applications, the equivalent Q -factor obtained is particularly interesting in the upper microwave range.     

8-GHz Narrowband High-Temperature Superconducting Filter With High Selectivity and Flat Group Delay

This paper reports a development of a narrowband high-temperature superconducting filter with both high selectivity and flat group delay. The filter has a center frequency of 8.625 GHz and a 3-dB bandwidth of 42 MHz (a fractional bandwidth of 0.49%). In order to achieve both high band-edge steepness and excellent group-delay flatness, we introduce a 14-resonator quasi-elliptic function response with three pairs of transmission zeros (one pair for high selectivity and two pairs for flat group delay) in the cascaded quadruplet coupling structure. We also develop a novel low radiation resonator (double-folded resonator) to reduce the parasitic coupling and meet other requirements for the 8-GHz filter. The filter was fabricated on a 2-in-diameter 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a midband insertion loss of 1.6 dB and a return loss better than 15.5 dB. Band-edge steepness reaches over 11.7 dB/MHz at both the high- and low-frequency edges. The 60-dB rectangle ratio is less than 1.25. The out-of-band rejection is over 70 dB at 5.98 MHz from the 3-dB band edge. The variation of group delay is less than 23 ns over 33 MHz (78.5% of 3-dB bandwidth), and less than 30 ns over 34.5 MHz (82% of 3-dB bandwidth).      

A single-chip Si-bipolar 1.6-GHz VCO with integrated-bias network

A single-chip 2.7-V voltage-controlled oscillator (VCO) with an integrated-bias network has been implemented in an Si-bipolar process with an f_T of 25 GHz. With an on-chip resonator consisting of vertically coupled inductors and varactor diodes, an oscillation frequency of 1.56 GHz was measured. A careful design of the oscillator and bias network was necessary to achieve a phase noise performance of -139 dBc/Hz at 4.7 h MHz off carrier. The tuning sensitivity was 100 MHz/V, which is sufficient to compensate for production tolerances. The VCO can be used as a building block for single-chip transceivers in digital European cordless telephone or global system for mobile communication systems     

8千兆赫介质带通滤波器

本文描述了介质窄带带通滤波器的设计方法,介绍了8千兆赫圆柱形介质谐振器窄带滤波器.该滤波器的中心频率为8059兆赫,带宽为±25兆赫,通带插损分别小于0.5分贝(三谐振器)和0.8分贝(四谐振器),阻带衰减分别大于25分贝(三谐振器)和35分贝(四谐振器),通带内驻波特性,其反射损耗大于25分贝.     

高频宽带晶体滤波器的研制

在目前获得高频钽酸锂晶体谐振器较难的情况下,该文以石英晶体为材料,通过化学腐蚀法,将谐振器的基波频率从45 MHz提高到63 MHz,并采用在传统差接桥型电路中插入LC调谐回路的电路展宽方式,将石英晶体滤波器的相对带宽从0.3%拓展到1%。基于该法研制出相对带宽约1%的63 MHz晶体滤波器,其带宽大于600 kHz,损耗为4 dB。     

Hybrid Dual-Mode Frequency Synthesis for Cognitive Multi-radio Front-Ends

This paper investigates a novel approach to reconfigurable frequency synthesis for flexible radio transceivers in future cognitive multi-radios. The frequency range covered by the proposed multi-radio synthesizer corresponds to the frequency bands of the most diffused wireless communication standards operating in the radio band ranging from 800 MHz to 6 GHz. A hybrid phase locked loop (PLL) based frequency synthesizer is proposed here and a novel switching protocol is presented and validated on an experimental evaluation board. The proposed architecture combines fractional and integer PLL modes of operation along with a switched loop filter topology. Compared to standard PLL techniques, the proposed configuration provides great flexibility options and moreover, it offers relatively low circuit complexity and low power consumption. The proposed architecture provides reconfigurability of the loop bandwidth, frequency resolution, phase noise and settling time performance and hence, it can adapt itself to diverse requirements given by the concerned wireless communication standards.     

Compact, narrow bandwidth, lumped element bandstop resonators

This letter describes the design and simulation of novel, highly compact, lumped element bandstop resonators. The resonators are fabricated using copper microstrip lines, with resonant frequencies around 5GHz but with areas of only 1.075mm /spl times/ 1.275mm. Each resonator consists of 8 interdigital capacitive fingers in parallel with a straight line inductor. The new design offers at least a 40% size reduction compared with similar resonators , . Furthermore, adjustment of the input and output feed line geometries enables resonator tuning at the design stage over a bandwidth of approximately 100MHz. The measured characteristics show good agreement with the simulated responses. Ultimate performance of this type of bandstop resonator is achieved using superconducting thin films, and to conclude a 20-finger, superconducting resonator (of area 1mm /spl times/ 0.41mm) is described and simulated.     

A cascaded continuous-time /spl Sigma//spl Delta/ Modulator with 67-dB dynamic range in 10-MHz bandwidth

This paper presents the design of a 2-2 cascaded continuous-time sigma-delta modulator. The cascaded modulator comprises two stages with second-order continuous-time resonator loopfilters, 4-bit quantizers, and feedback digital-to-analog converters. The digital noise cancellation filter design is determined using continuous-time to discrete-time transformation of the sigma-delta loopfilter transfer functions. The required matching between the analog and digital filter coefficients is achieved by means of simple digital calibration of the noise cancellation filter. Measurement results of a 0.18-/spl mu/m CMOS prototype chip demonstrate 67-dB dynamic range in a 10-MHz bandwidth at 8 times oversampling for a single continuous-time cascaded modulator. Two cascaded modulators in quadrature configuration provide 20-MHz aggregate bandwidth. Measured anti-alias suppression is over 50 dB for input signals in the band from 150 to 170 MHz around the sampling frequency of 160 MHz.     

Miniaturized SAW devices for radio communication transceivers

Various applications of surface-acoustic-wave (SAW) technologies are investigated in which the use of SAW devices would result in reduced volume and weight for VHF/UHF radio communication transceivers. Attention is given to improved insertion loss and power requirements reported for SAW filters. In particular, by analyzing the loss mechanisms of a previously developed high-performance SAW filter for mobile telephones, a new extremely low-loss SAW filter (loss of as low as 1.2-2.0 dB at 600 MHz) has been developed. The results of fundamental experiments for a SAW antenna duplexer using this new SAW filter as the transmitter filter with a semicoaxial filter as the receiver filter at 800 MHz are presented     

Design of a tapered coaxial resonator filter for mobilecommunications

The authors describe the design, a simple fabrication technique, and performance of a coaxial resonator filter with tapered inner conductors to be used in mobile radios. The effects of coupling, window area, and temperature on the performance of the filter have also been considered. The passband of the filter is 30 MHz with a center frequency of 925 MHz, 1.15-dB insertion loss, 0.8-dB ripple, and 14.7-dB return loss at the center frequency. The resonant frequency and coupling coefficient stabilities with temperature have been measured at 28.38 ppm/°C and 3.5×10^-4/°C, respectively. The 3-dB bandwidth is measured as 32 MHz and a sharp cutoff is observed at -16.5 dB with a bandwidth of 37 MHz for narrow scale and -65 dB with a bandwidth of 84 MHz for wide scale. The fabrication technique developed using a zinc-cast inner conductor and extruded aluminum outer conductor has better reproducibility than the conventional machining technique and is highly cost effective     

The effects of polarization rotation and phase delay with frequency on ionospherically propagated signals

When a CW skywave signal is received on a linearly polarized antenna, polarization (Faraday) rotation produces a variation of received signal strength with radio frequency. The resulting dependence of received signal amplitude on radio frequency may impose a bandwidth limitation on pulsed signals where waveform preservation is important. A measure of this limitation, termed polarization bandwidth, is defined to correspond to the bandwidth in which the plane of polarization rotates90deg. Computer ray-tracing calculations were performed using a single Chapman-layer ionospheric model to determine the 1-hop polarization bandwidth as a function of geomagnetic azimuth and radio frequency. The polarization bandwidth was found to decrease with increasing radio frequency and with increasingly close alignment of the propagation path with the longitudinal component of the earth's magnetic field. Assuming a critical frequency of 9 MHz and a path length of 2000 km, the polarization bandwidth increased from a minimum of 140 kHz at 10.5 MHz and from a minimum of 70 kHz at 17.5 MHz, as the propagation direction varied from geomagnetic north to east. A model for the 1-hop ionospheric signal channel is proposed whose parameters are the rate of change of polarization rotation with frequency and the phase versus frequency characteristic of the path. These two parameters are shown to be readily determined from FM-CW or equivalent oblique-path sounding records. Using this model, predictions are made of the effects of polarization rotation with frequency, and also of ionospheric dispersion or phase distortion, on the envelope shape of short-pulse signals (of from 1.5 to50 mus duration). A pronounced waveshape distortion due to the effects of polarization rotation on the pulse envelope was observed when the signal bandwidth appreciably exceeded the "polarization bandwidth" for the path.     

基于双模谐振器的双通带可调谐滤波器设计

从理论上分析了开路支节加载双频谐振器的谐振模式,通过在谐振器末端加载变容二极管的方式,设计了一款双通带独立可调谐滤波器。通过调节谐振器末端变容二极管电容值大小来改变通带的中心频率,通过调节支节末端的变容二极管来调节通带的带宽。该滤波器的两个通带之间相互独立,调谐其中一个通带对另一个通带几乎没有影响。通过引入源与负载的耦合,使得双通带两侧各产生一个传输零点,提高了滤波器的选择性和带外抑制能力。最终设计出的滤波器第一通带的中心频率在1.08~1.19 GHz之间连续可调,绝对带宽在112~152 MHz之间连续可调;第二通带中心频率在2.07~2.22 GHz 之间连续可调,其绝对带宽在132~189 MHz 之间连续可调。在调谐过程中,通过调节中心开路支节末端变容二极管加载直流电压大小,实现调谐过程两通带带宽基本维持不变。     

A 1.5 V 3.1 GHz–8 GHz CMOS Synthesizer for 9-Band MB-OFDM UWB Transceivers

This paper presents the design of a CMOS synthesizer for dual-conversion zero-IF2 Multi-Band OFDM (MB-OFDM) transceivers covering the first 9 frequency bands from 3.1GHz to 8.0GHz, each with a bandwidth of 528 MHz. A wideband single-sideband mixer with wideband inductive network loading is proposed. Moreover, a modified transformer-coupled quadrature VCO and interconnection-loading-insensitive layout technique are employed. Fabricated in TSMC 0.18-mum CMOS process and operated at 1.5V, the synthesizer measures phase noise of -127.4dBc/Hz at 10MHz offset, integrated phase noise of 4.43deg, sideband suppression of better than -22 dBc, and a switching time of less than 1ns while consuming 59 mA     

Design and Performance of an Ultra-Narrowband Superconducting Filter at UHF Band

A stepped impedance spiral resonator suitable for high-temperature superconducting (HTS) filter with bandwidth narrower than 0.5% is presented. An eight-pole demonstration HTS filter is developed with a central frequency of 650 MHz and a bandwidth of 0.3%. The measurements show that the insertion loss is less than 0.3 dB, and the return loss is better than 16 dB. The filter has out-of-band rejections of 65 dB at 2 MHz below the passband and 80 dB at 2 MHz above the passband, respectively.     

A monolithic CMOS 2368/spl plusmn/30 MHz transformer based Q-enhanced series-C coupled resonator bandpass filter

A three-pole 0.1 dB ripple Chebyshev series-C coupled resonator bandpass filter with transformer-based Q-enhancement is presented. This Q-enhancement technique compensates resonator loss and produces a flat passband response with low insertion loss. The compensation scheme uses frequency-dependent negative resistance to compensate frequency-dependent inductor losses, avoiding passband distortion, which is a problem with cross-coupled negative resistance circuits. Fabricated in 0.18 /spl mu/m CMOS, the measured filter center frequency is 2368 MHz with a 60 MHz (3 dB) bandwidth, including probe pad and connecting trace parasitic losses. The filter draws 5.84 mA at 1.5 V, and the die area is 1.5 mm/spl times/1.5 mm.     

FM noise and linewidth reduction in semiconductor laser weakly coupled to a single-mode fibre resonator

Optical feedback effects on spectral properties of an AlGaAs semiconductor laser weakly coupled to a single-mode fibre resonator with a Fabry-Perot transmission bandwidth of 15 MHz are reported. FM noise spectrum, linewidth and resonator output measurements are found to be in good agreement with theory.     

能陷理论在研究和设计低噪声石英谐振器中的应用

本文引用Shockley等人进行“能陷”分析得出的基本结论,将其用来研究和设计低噪声石英谐振器。将AT切型石英晶片等效为一组合“声波导”,经过推导与分析引出了与控制晶片中噪声有关的“响应带宽”和“内调制”两个参量,这两个参数可以通过设计谐振器的晶片和电极来加以控制。文中对设计制成的低噪声100MHz石英谐振器及其应用情况均作了介绍,列出了一些测试数据,得到了比较满意的结果,表明所提出的设计方法是有效的。     

A novel ultra-compact resonator for Superconducting thin-film filters

This paper proposes a novel thin-film resonator structure, which combines the microstrip resonator and the coplanar resonator to form an integrated resonator. This resonator structure has an extremely compact size, as compared to the thin-film resonator structures from the literature, and its resonant frequency was shown theoretically to be less sensitive to, or even insensitive to, the thickness of the substrate. An eight-pole quasi-elliptic filter based on this novel resonator was designed. The exact filter layout was simulated and optimized by full-wave electromagnetic simulation using IE3D software. The full-wave simulated filter response was in good agreement with the theoretical filter response. A filter was fabricated on a double-sided YBa/sub 2/Cu/sub 3/O/sub 7/ thin film epitaxially grown on a 2-in-diameter MgO wafer. The measured filter response showed a bandwidth of 1.5 MHz and a center frequency of 850.3 MHz at 78 K. The insertion loss at the passband center was 1 dB, corresponding to a filter Q of 28 000. Steep rejection slopes were obtained at the band edges and rejections reached over 70 dB in approximately 300 kHz from the passband edges. No pronounced changes were observed for input power levels between -20-0 dBm, indicating a relatively high power-handling capability of the filter.     

高性能声表面波调频振荡器的研究

分析了声表面波谐振器的性能 ,论述了声表面波振荡器的工作原理及设计方法 ,最终完成中心频率为797.3 MHz的振荡电路 ,调频带宽 2 MHz(2 5 0 0 PPM)。文中对影响调频带宽、相位噪声的因素进行了分析讨论。本项目研究成果已获得实际应用     

CMOS wideband analogue delay stage

A new second-order all-pass filter with maximum achievable delay-bandwidth-product (DBW) is presented. The proposed circuit will be used as a wideband delay element in impulse radio ultra-wideband transceivers. Benefiting from a simple architecture, the proposed circuit achieves a 60 ps delay across a 10 GHz bandwidth, which is the largest delay ever reported over such a wide bandwidth. In addition, the most noticeable advantage of this delay circuit is the small variation of group delay across a wide frequency range, which means negligibly small phase distortion introduced by the circuit