225 research outputs found

    RF CMOS Oscillators for Modern Wireless Applications

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    While mobile phones enjoy the largest production volume ever of any consumer electronics products, the demands they place on radio-frequency (RF) transceivers are particularly aggressive, especially on integration with digital processors, low area, low power consumption, while being robust against process-voltage-temperature variations. Since mobile terminals inherently operate on batteries, their power budget is severely constrained. To keep up with the ever increasing data-rate, an ever-decreasing power per bit is required to maintain the battery lifetime. The RF oscillator is the second most power-hungry block of a wireless radio (after power amplifiers). Consequently, any power reduction in an RF oscillator will greatly benefit the overall power efficiency of the cellular transceiver. Moreover, the RF oscillators' purity limits the transceiver performance. The oscillator's phase noise results in power leakage into adjacent channels in a transmit mode and reciprocal mixing in a receive mode. On the other hand, the multi-standard and multi-band transceivers that are now trending demand wide tuning range oscillators. However, broadening the oscillator’s tuning range is usually at the expense of die area (cost) or phase noise. The main goal of this book is to bring forth the exciting and innovative RF oscillator structures that demonstrate better phase noise performance, lower cost, and higher power efficiency than currently achievable. Technical topics discussed in RF CMOS Oscillators for Modern Wireless Applications include: Design and analysis of low phase-noise class-F oscillators Analyze a technique to reduce 1/f noise up-conversion in the oscillators Design and analysis of low power/low voltage oscillators Wide tuning range oscillators Reliability study of RF oscillators in nanoscale CMO

    High Performance Optical Transmitter Ffr Next Generation Supercomputing and Data Communication

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    High speed optical interconnects consuming low power at affordable prices are always a major area of research focus. For the backbone network infrastructure, the need for more bandwidth driven by streaming video and other data intensive applications such as cloud computing has been steadily pushing the link speed to the 40Gb/s and 100Gb/s domain. However, high power consumption, low link density and high cost seriously prevent traditional optical transceiver from being the next generation of optical link technology. For short reach communications, such as interconnects in supercomputers, the issues related to the existing electrical links become a major bottleneck for the next generation of High Performance Computing (HPC). Both applications are seeking for an innovative solution of optical links to tackle those current issues. In order to target the next generation of supercomputers and data communication, we propose to develop a high performance optical transmitter by utilizing CISCO Systems®\u27s proprietary CMOS photonic technology. The research seeks to achieve the following outcomes: 1. Reduction of power consumption due to optical interconnects to less than 5pJ/bit without the need for Ring Resonators or DWDM and less than 300fJ/bit for short distance data bus applications. 2. Enable the increase in performance (computing speed) from Peta-Flop to Exa-Flops without the proportional increase in cost or power consumption that would be prohibitive to next generation system architectures by means of increasing the maximum data transmission rate over a single fiber. 3. Explore advanced modulation schemes such as PAM-16 (Pulse-Amplitude-Modulation with 16 levels) to increase the spectrum efficiency while keeping the same or less power figure. This research will focus on the improvement of both the electrical IC and optical IC for the optical transmitter. An accurate circuit model of the optical device is created to speed up the performance optimization and enable co-simulation of electrical driver. Circuit architectures are chosen to minimize the power consumption without sacrificing the speed and noise immunity. As a result, a silicon photonic based optical transmitter employing 1V supply, featuring 20Gb/s data rate is fabricated. The system consists of an electrical driver in 40nm CMOS and an optical MZI modulator with an RF length of less than 0.5mm in 0.13&mu m SOI CMOS. Two modulation schemes are successfully demonstrated: On-Off Keying (OOK) and Pulse-Amplitude-Modulation-N (PAM-N N=4, 16). Both versions demonstrate signal integrity, interface density, and scalability that fit into the next generation data communication and exa-scale computing. Modulation power at 20Gb/s data rate for OOK and PAM-16 of 4pJ/bit and 0.25pJ/bit are achieved for the first time of an MZI type optical modulator, respectively

    RF CMOS Oscillators for Modern Wireless Applications

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    While mobile phones enjoy the largest production volume ever of any consumer electronics products, the demands they place on radio-frequency (RF) transceivers are particularly aggressive, especially on integration with digital processors, low area, low power consumption, while being robust against process-voltage-temperature variations. Since mobile terminals inherently operate on batteries, their power budget is severely constrained. To keep up with the ever increasing data-rate, an ever-decreasing power per bit is required to maintain the battery lifetime. The RF oscillator is the second most power-hungry block of a wireless radio (after power amplifiers). Consequently, any power reduction in an RF oscillator will greatly benefit the overall power efficiency of the cellular transceiver. Moreover, the RF oscillators' purity limits the transceiver performance. The oscillator's phase noise results in power leakage into adjacent channels in a transmit mode and reciprocal mixing in a receive mode. On the other hand, the multi-standard and multi-band transceivers that are now trending demand wide tuning range oscillators. However, broadening the oscillator’s tuning range is usually at the expense of die area (cost) or phase noise. The main goal of this book is to bring forth the exciting and innovative RF oscillator structures that demonstrate better phase noise performance, lower cost, and higher power efficiency than currently achievable. Technical topics discussed in RF CMOS Oscillators for Modern Wireless Applications include: Design and analysis of low phase-noise class-F oscillators Analyze a technique to reduce 1/f noise up-conversion in the oscillators Design and analysis of low power/low voltage oscillators Wide tuning range oscillators Reliability study of RF oscillators in nanoscale CMO

    Maximizing the performance for microcomb based microwave photonic transversal signal processors

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    Microwave photonic (MWP) transversal signal processors offer a compelling solution for realizing versatile high-speed information processing by combining the advantages of reconfigurable electrical digital signal processing and high-bandwidth photonic processing. With the capability of generating a number of discrete wavelengths from micro-scale resonators, optical microcombs are powerful multi-wavelength sources for implementing MWP transversal signal processors with significantly reduced size, power consumption, and complexity. By using microcomb-based MWP transversal signal processors, a diverse range of signal processing functions have been demonstrated recently. In this paper, we provide a detailed analysis for the processing inaccuracy that is induced by the imperfect response of experimental components. First, we investigate the errors arising from different sources including imperfections in the microcombs, the chirp of electro-optic modulators, chromatic dispersion of the dispersive module, shaping errors of the optical spectral shapers, and noise of the photodetector. Next, we provide a global picture quantifying the impact of different error sources on the overall system performance. Finally, we introduce feedback control to compensate the errors caused by experimental imperfections and achieve significantly improved accuracy. These results provide a guide for optimizing the accuracy of microcomb-based MWP transversal signal processors.Comment: 15 pages, 12 figures, 60 reference

    A Low Phase Noise Wide-Tuning Range Class-F VCO Based on a Dual-Mode Resonator in 65nm CMOS

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    A Voltage Controlled Oscillator (VCO) is a critical building block in the design of current frequency synthesizers for RF system applications. State-of-the-art operation defines that an oscillator should have the best spectral purity while consuming low amount of power for a wide tuning range. With this in mind, this work presents a low phase noise wide tuning range ClassF VCO using a dual-mode resonator. In comparison to other conventional wideband oscillators, the proposed capacitively/inductively-coupled resonator will integrate the benefits of Class-F voltage control oscillators and dual-mode switching networks to obtain simultaneous low phase noise and wide-tuning range. The proposed structure, prototyped in 65nm TSMC CMOS technology, shows a 2.14 – 4.22GHz continuous tuning range, phase noise figure-of-merit (FoM) of 192.7dB at 2.3GHz and better than 188dB across the entire operating frequency range. The oscillator consumes 15-16.4mW from a 0.6V supply and occupies an active area of 0.7mm^2 . In conclusion, the proposed resonator achieves 2- 3dB phase noise improvement while achieving 65% overall tuning range when compared to a typical class-F VCO architecture

    Automatic Tuning of Silicon Photonics Millimeter-Wave Transceivers Building Blocks

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    Today, continuously growing wireless traffic have guided the progress in the wireless communication systems. Now, evolution towards next generation (5G) wireless communication systems are actively researched to accommodate expanding future data traffic. As one of the most promising candidates, integrating photonic devices in to the existing wireless system is considered to improve the performance of the systems. Emerging silicon photonic integrated circuits lead this integration more practically, and open new possibilities to the future communication systems. In this dissertation, the development of the electrical wireless communication systems are briefly explained. Also, development of the microwave photonics and silicon photonics are described to understand the possibility of the hybrid SiP integrated wireless communication systems. A limitation of the current electrical wireless systems are addressed, and hybrid integrated mm-wave silicon photonic receiver, and silicon photonic beamforming transmitter are proposed and analyzed in system level. In the proposed mm-wave silicon photonic receiver has 4th order pole-zero silicon photonic filter in the system. Photonic devices are vulnerable to the process and temperature variations. It requires manual calibration, which is expensive, time consuming, and prone to human errors. Therefore, precise automatic calibration solution with modified silicon photonic filter structure is proposed and demonstrated. This dissertation demonstrates fully automatic tuning of silicon photonic all-pass filter (APF)-based pole/zero filters using a monitor-based tuning method that calibrates the initial response by controlling each pole and zero individually via micro-heaters. The proposed tuning approach calibrates severely degraded initial responses to the designed elliptic filter shapes and allows for automatic bandwidth and center frequency reconfiguration of these filters. This algorithm is demonstrated on 2nd- and 4th-order filters fabricated in a standard silicon photonics foundry process. After the initial calibration, only 300ms is required to reconfigure a filter to a different center frequency. Thermal crosstalk between the micro-heaters is investigated, with substrate thinning demonstrated to suppress this effect and reduce filter calibration to less than half of the original thick substrate times. This fully automatic tuning approach opens the possibility of employing silicon photonic filters in real communication systems. Also, in the proposed beamforming transmitter, true-time delay ring resonator based 1x4 beamforming network is imbedded. A proposed monitor-based tuning method compensates fabrication variations and thermal crosstalk by controlling micro-heaters individually using electrical monitors. The proposed tuning approach successfully demonstrated calibration of OBFN from severely degraded initial responses to well-defined group delay response required for the targeted radiating angle with a range of 60â—¦ (-30â—¦ to 30â—¦ ) in a linear beamforming antenna array. This algorithm is demonstrated on OBFN fabricated in a standard silicon photonics foundry process. The calibrated OBFN operates at 30GHz and provide 2GHz bandwidth. This fully automatic tuning approach opens the possibility of employing silicon OBFN in real wideband mm-wave wireless communication systems by providing robust operating solutions. All the proposed photonic circuits are implemented using the standard silicon photonic technologies, and resulted in several publications in IEEE/OSA Journals and Conferences

    Widely tunable silicon Raman laser

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    Stimulated Raman scattering is an effective means of wavelength conversion and can largely extend the operating spectral range of an optical source. We demonstrate a highperformance tunable Raman laser on a sub-micrometer-thick silicon on insulator wafer using a standard foundry process. The key feature to this laser is the use of a tunable coupling mechanism to adjust both pump and signal coupling coefficients in the ring cavity, allowing demonstration of laser emission over a large wavelength tuning range of 83 nm. This Raman laser demonstrates efficient (slope of up to 26% and a maximum pump-to-signal power conversion efficiency of 10%) on-chip non-linear wavelength conversion. Our results indicate great promise for substantially increasing the optical spectral resources available on a silicon chip

    Construction of a linear ion trap and engineering controlled spin-motional interactions

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    This thesis outlines the design and construction of an experimental system for confining and manipulating 171Yb+ ions in a linear trap. The experimental system is used to demonstrate two complementary techniques relating to entangling gates in trapped ions. Firstly, phase-modulated pulse sequences are used to perform motion-mediated entangling gates in a manner that enables robustness to noise, parameter flexibility and the ability to generate entanglement in large ion registers. Secondly, phase- and amplitude-modulated pulse sequences with tuneable noise sensitivity are used to perform spectrally-resolved sensing of fluctuations in the motional frequency of trapped ions. Together, these techniques form a joint framework for the measurement and suppression of error in trapped ion entangling gates

    High-frequency oscillator design for integrated transceivers

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    Chip-scale optical frequency comb sources for terabit communications

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    To keep up with the ever-increasing data transmission speed needs, data center interconnects are scaling up to provide multi-Tbit/s connectivity. These links require a high number of WDM channels, while the associated transceivers should be compact and energy efficient. Scaling the number of channels, however, is still limited by the lack of adequate optical sources. In this book, we investigate novel chip-scale frequency comb generators as multi-wavelength light sources for Tbit/s WDM links
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