一种基于相位调制器的40 GHz OFDM-ROF系统实验研究

实验研究了一种基于相位调制器(PM)并级联强度调制器(IM)实现40 GHz毫米波传输正交频分复用(OFDM)信号的光纤无线通信(ROF)系统。在中心站,采用20 GHz的射频(RF)信号驱动PM,调节驱动信号的强度,使输出的信号经光纤布拉格光栅(FBG)滤除中心载波后再送入IM。2.5 Gbit/s的OFDM信号直接调制在光毫米波上,经过50 km标准的单模光纤(SSMF)传输到基站。在基站,光调制信号经光电转换器(PD)转换成电调制信号,再与RF信号混频,恢复出基带OFDM信号。实验结果表明,在无色散补偿、误码率(BER)为10-3的条件下,下行链路中2.5 Gbit/s的OFDM信号经光纤传输50 km后,其功率代价小于1 dB,而且信号的星座图依然较好。     

60GHz微带波导转换结构设计及其在通信集成前端中的应用

60 GHz无线通信技术具有非常宽的带宽,可以应用于超高速无线数据传输,已经成为第四代无线通信的重要组成部分,学术界和工业界对此投入了持续的关注。对60 GHz频段微带波导转换结构进行了设计,结果显示在57 GHz～64 GHz通信频率范围内,插入损耗小于1 dB,回波损耗小于-15 dB,达到了实用化要求。并利用MMIC芯片完成了60 GHz毫米波通信系统T/R模块的集成设计,对QPSK通信体制下的调制和解调信号进行了分析,验证了系统的可行性。     

An All-Digital RF Signal Generator Using High-Speed $DeltaSigma$ Modulators

An all-digital RF signal generator using DeltaSigma modulation and targeted at transmitters for mobile communication terminals has been implemented in 90 nm CMOS. Techniques such as redundant logic and non-exact quantization allow operation at up to 4 GHz sample rate, providing a 50 MHz bandwidth at a 1 GHz center frequency. The peak output power into a 100 Omega diff. load is 3.1 dBm with 53.6 dB SNDR. By adjusting the sample rate, carriers from 50 MHz to 1 GHz can be synthesized. RF signals up to 3 GHz can be synthesized when using the first image band. As an example, UMTS standard can be addressed by using a 2.6 GHz clock frequency. The measured ACPR is then 44 dB for a 5 MHz WCDMA channel at 1.95 GHz with output power of -16 dBm and 3.4% EVM. At 4 GHz clock frequency the total power consumption is 120 mW (49 mW for DeltaSigma modulator core) on a 1 V supply voltage, total die area is 3.2 mm² (0.15 mm² for the active area).     

11GHz微波光子信号的单边带布里渊选择放大实验研究

提出一种实现11GHz微波光子信号单边带布里渊选择放大的简单系统,对该系统进行了研究,理论分析了11GHz微波光子信号下边带的光功率变化,通过实验实现了11GHz微波光子信号的单边带选择放大,得到了30dB单边带增益。对实验测得的边带光功率随泵浦波光功率的变化进行了讨论,实验结果和理论计算相吻合。     

Generation and transmission of millimeter-wave data-modulated optical signals using an optical injection phase-lock loop

Generation and transmission of millimeter-wave data-modulated optical signals is presented using an optical injection phase-lock loop (OIPLL). Millimeter-wave signal generation is demonstrated with wide locking range, 30-GHz low phase noise level, -93 dBc/Hz, and a wide frequency tuning range, 4-60 GHz generation demonstrated using optical injection locking only, verified by using OIPLL in the 26-40 GHz range. The OIPLL is also used to transmit error-free 140-Mb/s amplitude shift keying and 68-Mb/s differential phase-shift keying (DPSK) modulated millimeter-wave signals over up to 65 km of uncompensated standard singlemode fiber. The DPSK system uses reference frequency modulation, eliminating the need for optical amplification.     

A 4 GHz quadrature output fractional-N frequency synthesizer for an IR-UWB transceiver

This paper describes a 4 GHz fractional-N frequency synthesizer for a 3.1 to 5 GHz IR-UWB transceiver.Designed in a 0.18μm mixed-signal & RF 1P6M CMOS process, the operating range of the synthesizer is 3.74 to 4.44 GHz. By using an 18-bit third-order ∑-△ modulator, the synthesizer achieves a frequency resolution of 15 Hz when the reference frequency is 20 MHz. The measured amplitude mismatch and phase error between I and Q signals are less than 0.1 dB and 0.8° respectively. The measured phase noise is -116 dBc/Hz at 3 MHz offset for a 4 GHz output.Measured spurious tones are lower than -60 dBc. The settling time is within 80 μs. The core circuit conupSigmaes only 38.2 mW from a 1.8 V power supply.     

脉幅有序变化OTDM信号的支路及群路全光时钟提取

将含暗帧脉冲的 4× 2 .5GHz的光时分复用 (OTDM)信号注入一含半导体光放大器 (SOA)的锁模光纤激光器 ,利用SOA的交叉增益调制效应 ,提取出 2 .5GHz的支路时钟信号和 5GHz,10GHz的群路时钟信号 ;群路时钟的提取机制是有理数谐波锁模机制。光时分复用信号采用暗帧脉冲不但可以用来识别支路信号 ,而且显著提高了支路时钟信号的质量     

利用半导体光放大器环路镜实现4×2.5GHzOTDM解复用

报道了利用半导体光放大器环路镜对４×２．５ＧＨｚ光时分复用（ＯＴＤＭ）进行全光解复用的实验，实验结果表明用该方法解复用可得到具有很好消光比的解复用信号。     

100 GHz active electronic probe for on-wafer S-parameter measurements

Reports the development of an active electronic probe for 100 GHz on-wafer S-parameter measurements. Integrated on the substrate of this wafer probe were a quintupler for 100 GHz stimulus signal generation, two directional couplers for incident and reflected signals sampling, and two newly developed harmonic mixers to down-convert these 100 GHz signals to 20 MHz. The authors also demonstrate all-electronic on-wafer 75-100 GHz two-port S-parameter measurements using these probes.<>     

Microwave Photonic Signal Down‐Conversion Using a Novel Two‐Frequency Bragg Grating Based Brillouin Fiber Laser

A simple technique using a novel two‐frequency Bragg grating based Brillouin fiber laser to down‐convert high frequency microwave photonic signals is presented. The mechanism of the Brillouin fiber laser and the principle of this technique for microwave photonic signal down‐conversion are analyzed. The 12GHz microwave photonic signals are experimentally down‐converted to 1.13GHz IF signal with the technique.     

Design and implementation of a 94 GHz CMOS down-conversion mixer with integrated miniature planar baluns for image radar sensors

A 94 GHz down-conversion mixer for image radar sensors using standard 90 nm CMOS technology is reported. The down-conversion mixer comprises a double-balanced Gilbert cell with peaking inductors between RF transconductance stage and LO switching transistors for conversion gain (CG) enhancement and noise figure suppression, a miniature planar balun for converting the single RF input signals to differential signals, another miniature planar balun for converting the single LO input signals to differential signals, and an IF amplifier. The mixer consumes 22.5 mW and achieves excellent RF-port input reflection coefficient of ?10 to ?35.9 dB for frequencies of 87.6–104.4 GHz, and LO-port input reflection coefficient of ?10 to ?31.9 dB for frequencies of 88.2–110 GHz. In addition, the mixer achieves CG of 4.9–7.9 dB for frequencies of 81.8–105.8 GHz (the corresponding 3-dB CG bandwidth is 24 GHz) and LO–RF isolation of 37.7–47.5 dB for frequencies of 80–110 GHz, one of the best CG and LO–RF isolation results ever reported for a down-conversion mixer with operation frequency around 94 GHz. Furthermore, the mixer achieves an excellent input third-order intercept point of ?3 dBm at 94 GHz. These results demonstrate the proposed down-conversion mixer architecture is promising for 94 GHz image radar sensors.     

A low-voltage,low power divide-by-4 LC-tank injection-locked frequency divider

A low-voltage wide locking range injection-locked frequency divider (ILFD) using a standard 0.18?µm complementary metal-oxide-semiconductor process is presented. The ILFD is based on a differential LC VCO with one injection metal oxide semiconductor field effect transistor (MOSFET) for coupling external signals to the resonator. The low-voltage operation and wide locking range is obtained by boosting the gate voltage swing of the ILFD. Measurements show that at the supply voltage of 0.67?V, the divider's free-running frequency is tunable from 3.91 to 4.22?GHz, and the core power consumption is 1.87?mW. At the incident power of 0?dBm the divide-by-4 operation range is about 2?GHz (12.3%), from the incident frequency 15.3–17.3?GHz. The divide-by-2 locking range is about 5.1?GHz (77%), from the incident frequency 4.1–9.2?GHz.     

High-speed experiments on a QFP-based comparator for ADCs with18-GHz sample rate and 5-GHz input frequency

The authors report on the high-speed operation of a superconducting comparator circuit, based on coupling the quantum flux parametron (QFP) to an RF SQUID, which can be used to build a flash-type analog-to-digital converter (ADC). Simulations of this circuit show that it is expected to achieve operation with input signal bandwidths greater than 4 GHz and with a dynamic range equal to at least 4 b of resolution. A QFP-based comparator fabricated with a process using NbN/Pb-alloy Josephson junctions of 5 μm by 5 μm and a current density of 100 A/cm² has been examined to evaluate the properties of the QFP-ADC. Analog-to-digital conversion of the comparator has been observed with a QFP activation frequency up to 18.2 GHz. By employing a sampling method, input signals with frequencies up to 5.4 GHz have also been digitized     

Spectral efficiency analysis of digital signals for 3.1–10.6 GHz ultra-wideband radio systems

Spectral efficiency analysis of widely used types of digital signals in the 3.1–10.6 GHz frequency band is presented. Peculiarities of energy accumulation in the specified frequency band are demonstrated for video signals and modulated signals. Optimal durations, which provide maximum value of spectral efficiency, of the considered video signals are determined. Practical recommendations on using the considered digital signals in the 3.1–10.6 GHz ultra-wideband radio systems are concluded.     

Miniaturized quad-channel microstrip diplexer with low insertion loss and wide stopband for multi-service wireless communication systems

Wireless Networks - In this paper, a compact four-channel diplexer is designed using a microstrip structure to separate input signals at 2.07/3.94&nbsp;GHz and 2.37/4.49&nbsp;GHz and load...     

High-frequency broad-band signal generation using a semiconductor laser with a chaotic optical injection

Chaotic signals with a flat power spectrum over 20 GHz have been generated using two commercially available semiconductor lasers coupled in a unidirectional master-slave scheme. The master laser has an external optical feedback that induces optical chaos in the laser output. A part of the chaotic light output from the master laser is injected into the slave laser. We experimentally demonstrated the generation of broad-band signals up to 22 GHz using lasers whose relaxation oscillation frequency in the free-running state is only around 6.4 GHz. We also show that the experimental results can be well reproduced by numerical simulations using two coupled rate equations. The numerical investigation shows that the high-frequency broad-band signal generation is owing to two key effects: high-frequency oscillations as a result of beating between the master and slave laser lights, and spectrum flattening due to the injection of the chaotic signal. The flatness, stability, and tunability of the power spectra demonstrated in our experiments suggests that the proposed system can be potentially useful for generation of high-frequency broad-band random signals.     

Measurements of low angle fading in the Canadian arctic

In July 1974, an experiment was conducted at Eureka, Canada (80° N, 86° W), to measure the tropospheric fading of satellite signals at 4 and 6 GHz. At Eureka, the 4.6 m antenna was located on a hill 250 m above sea level providing a clear path at an elevation angle of 1° to the Anik II satellite. The 4 GHz downlink signal strength was recorded at Eureka. Fading of the 6 GHz uplink signal from Eureka was measured at the Communications Research Centre, Ottawa. The uplink and downlink fading contributions for the entire experimental period are nearly identical, indicating that the fading distributions are essentially frequencyindependent over the 4–6 GHz range. For the 18 days period of the experiment, the link margins are 10.8 dB and 20.3 dB for 99 % and 99.9 % reliability, respectively. For the worst twohour period, the margins are 18 dB and 28 dB, corresponding to those for a Rayleigh distribution. No marked diurnal effect is discernible. Distributions of the fade durations indicate, for example, that 90 % of all fades exceeding 6 dB do not exceed 36 seconds duration. Although fading at 4 GHz is always accompanied by fading at 6 GHz, their correlation is sometimes poor, yielding correlation coefficients as low as 0.34. The amplitude correlation of two 6 GHz signals separated by up to 10 MHz always exceeds 0.90, indicating minimal amplitude distortion across the band. The implications of these results on the design of a satellite link are discussed.     

Multiple-frequency basestation RoF system based on polarization multiplexed FWM in SOA

An approach of multiple-frequency millimeter-wave(mm-wave)signal generation is proposed for radio-over-fiber(RoF)system with multiple-frequency basestations(MFBSs).Two groups of orthogonally polarized signals are injected into a semiconductor optical amplifier(SOA),and subsequently ten new different wavelengths are generated via four-wave mix-ing(FWM)effect.At each MFBS,different wavelengths are filtered out using demultiplexer and then input to a photodiode(PD)to generate the mm-wave signals with the frequencies from 52 GHz to 68 GHz at the interval of 2 GHz.Simulation results verify that the proposed multiple-frequency generation for MFBS RoF system can work properly.     

A novel real-time Fourier and inverse Fourier transforming system based on non-uniform coupled-line phaser

A novel real-time Fourier and inverse Fourier transforming (RTFaIFT) system realizing both positive and inverse transformations is designed and verified, using non-uniform coupled-line phaser. Two kinds of Fourier transformations are integrated within one system for the first time. This system can map the spectrum of the input signal into a waveform in time domain whose amplitude mimics the spectrum magnitude, owing to the frequency-varying group delay (GD) response of the phaser. Furthermore, the correspondence between the output waveform and the spectrum of the input signal is given for accurate analysis of the spectrum. This configuration possesses the characteristic of compact structure, simple design procedure, and perfect performance, consisting of a mixer, a phaser with linear group delay, a diode, and a LPF. For experimental demonstration, a RTFaIFT system operating at 6 GHz is designed and fabricated, the bandwidth of which is 4 GHz with −0.5 ns/GHz GD slope. Both single- and double-pulse signals have been chosen as the test signals to verify the performance of the RTFaIFT system, respectively. The experimental results agree well with simulation and theoretical results.     

A 4 GS/s 4 bit ADC with 3.8 GHz analog bandwidth in GaAs HBT technology

An ultra-wideband 4 GS/s 4 bit analog-to-digital converter(ADC)which is fabricated in 2-level interconnect, 1.4μm InGaP/GaAs HBT technology is presented.The ADC has a-3 dB analog bandwidth of 3.8 GHz and an effective resolution bandwidth(ERBW)of 2.6 GHz.The ADC adopts folding-interpolating architecture to minimize its size and complexity.A novel bit synchronization circuit is used in the coarse quantizer to eliminate the glitch codes of the ADC.The measurement results show that the chip achieves larger than 3.4 ENOBs with an input frequency band of DC-2.6 GHz and larger than 3.0 ENOBs within DC-4GHz at 4 GS/s.It has 3.49 ENOBs when increasing input power by 4 dB at 6.001 GHz of input.That indicates that the ADC has the ability of sampling signals from 1st to 3rd Nyquist zones(DC-6 GHz).The measured DNL and INL are both less than±0.15 LSB. The ADC consumes power of 1.98 W and occupies a total area of 1.45×1.45 mm~2.