12 research outputs found

    Photonic RF Channelization Based on Microcombs

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    In recent decades, microwave photonic channelization techniques have developed significantly. Characterized by low loss, high versatility, large instantaneous bandwidth, and immunity to electromagnetic interference, microwave photonic channelization addresses the requirements of modern radar and electronic warfare for receivers. Microresonator-based optical frequency combs are promising devices for photonic channelized receivers, enabling full advantage of multicarriers, large bandwidths, and accelerating the integration process of microwave photonic channelized receivers. In this paper, we review the research progress and trends in microwave photonic channelization, focusing on schemes that utilize integrated microcombs. We discuss the potential of microcomb-based RF channelization, as well as their challenges and limitations, and provide perspectives for their future development in the context of on-chip silicon-based photonics.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

    Circuit Techniques for Multiple and Wideband Beamforming

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    University of Minnesota Ph.D. dissertation.June 2018. Major: Electrical Engineering. Advisor: Ramesh Harjani. 1 computer file (PDF); x, 102 pages.This thesis presents different architectures with regard to multiple beamforming and wideband phased array transceiver. Three different designs are implemented in TSMC 65nm RF CMOS to demonstrate different solutions. The design in this thesis have included major RF blocks in state-of-art wireless transceiver: RF receiver, local oscillator, and RF transmitter. First, a RF/analog FFT based four-channel four-beam receiver with progressive partial spatial ltering is proposed. This architecture is particularly well suited for MIMO systems where multiple beams are used to increase throughput. Like the FFT, the proposed architecture reuses computations for multi-beam systems. In particular, the proposed architecture redistributes the computations so as to maximize the reuse of the structure that already exist in a receiver chain. In many fashions the architecture is quite similar to a Butler matrix but unlike the Butler matrix it does not use large passive components at RF. Further, we exploit the normally occurring quadrature down-conversion process to implement the tap weights. In comparison to traditional MIMO architectures, that effectively duplicate each path, the distributed computations of this architecture provide partial spatial ltering before the final stage, improving interference rejection for the blocks between the LNA and the ADC. Additionally, because of the spatial ltering prior to the ADC, a single interferer only jams a single beam allowing for continued operation though at a lower combined throughput. The four-beam receiver core prototype in 65nm CMOS implements the basic FFT based architecture but does not include an LNA or extensive IF stages. This four-channel design consumes 56mW power and occupies an active area of 0:65mm2 excluding pads and test circuits. Second, a wideband phased array receiver architecture with simultaneous spectral and spatial filtering by sub-harmonic injection oscillators is presented. The design avoids using expensive delay elements by many conventional wideband phased array. Different from prior art of channelization which cannot solve beam-squinting issue among the sub-channels, we use sub-harmonic injection locking scheme, which make the center frequencies of all sub-channels point to the same spatial direction to overcome beam-squinting issue. The low frequency, low power and narrowband phase shifters are placed at LO in comparison to conventional way of placing delay elements or phase shifters in the signal path. This avoids receiver performance degradation from delay elements or phase shifters. The simultaneous spectral and spatial ltering dictates less ADC dynamic range requirement and further reduces power. The injection locking scheme reduces the phase noise contribution from the oscillators. The two-band prototype design realized in 65nm GP CMOS is centered at 9GHz, provides 4GHz instantaneous bandwidth, reduces beam-squinting by half, consumes 31.75mW/antenna and occupies 2.7mm2 of chip area. In the third work, a steerable RF/analog FFT based four-beam transmitter architecture is presented. This work is based on the idea of FFT based multiple beamforming in 1st work, but extended to the transmitter and make the all beams steerable. Due to the reciprocity between receiver and transmitter, decimation-in-frequency (DIF) FFT is utilized in the transmitter. All the beams are steered simultaneously by front-end phase shifters, while keep each of the beams is independent of the others. The steerability of FFT based multiple beamforming scheme makes this proposed prototype could tackle more complicated portable wireless environment. The first and second proposed architecture have been silicon veried, and the design of the third has been finished and ready for tapeout

    Microwave Photonic Signal Processing Using On-Chip Nonlinear Optics

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    The field of microwave photonics (MWP) emerged as a solution to the challenges faced by electronic systems when dealing with high-bandwidth RF and microwave signals. Photonic devices are capable of handling immense bandwidths thanks to the properties of light. MWP therefore employs such devices to process and distribute the information carried by RF and microwave signals, enabling significantly higher capacity compared to conventional electronics. The photonic devices traditionally used in MWP circuits have mainly comprised bulky components, such as spools of fibre and benchtop optical amplifiers. While achieving impressive performance, these systems were not capable of competing with electronics in terms of size and portability. More recently, research has focused on the application of photonic chip technology to the field of MWP in order to reap the benefits of integration, such as reductions in size, weight, cost, and power consumption. Integrated MWP however is still in its infancy, and ongoing research efforts are exploring new ways to match integrated photonic devices to the unique requirements of MWP circuits. This work investigates the application of on-chip nonlinear optical interactions to MWP. Nonlinear optics enables light-on-light interactions (not normally possible in a linear regime) which open a vast array of powerful functionalities. In particular, this thesis focuses on stimulated Brillouin scattering, resulting from the interaction of light with hypersonic sound waves, and four-wave mixing, where photons exchange energies. These two nonlinear effects are applied to implement MWP ultra-high suppression notch filters, wideband phase shifters, and ultra-fast instantaneous frequency measurement systems. Experimental demonstrations using integrated optical waveguides confirm record results

    Design of large polyphase filters in the Quadratic Residue Number System

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    Microwave Photonic Signal Processing Using On-Chip Nonlinear Optics

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    The field of microwave photonics (MWP) emerged as a solution to the challenges faced by electronic systems when dealing with high-bandwidth RF and microwave signals. Photonic devices are capable of handling immense bandwidths thanks to the properties of light. MWP therefore employs such devices to process and distribute the information carried by RF and microwave signals, enabling significantly higher capacity compared to conventional electronics. The photonic devices traditionally used in MWP circuits have mainly comprised bulky components, such as spools of fibre and benchtop optical amplifiers. While achieving impressive performance, these systems were not capable of competing with electronics in terms of size and portability. More recently, research has focused on the application of photonic chip technology to the field of MWP in order to reap the benefits of integration, such as reductions in size, weight, cost, and power consumption. Integrated MWP however is still in its infancy, and ongoing research efforts are exploring new ways to match integrated photonic devices to the unique requirements of MWP circuits. This work investigates the application of on-chip nonlinear optical interactions to MWP. Nonlinear optics enables light-on-light interactions (not normally possible in a linear regime) which open a vast array of powerful functionalities. In particular, this thesis focuses on stimulated Brillouin scattering, resulting from the interaction of light with hypersonic sound waves, and four-wave mixing, where photons exchange energies. These two nonlinear effects are applied to implement MWP ultra-high suppression notch filters, wideband phase shifters, and ultra-fast instantaneous frequency measurement systems. Experimental demonstrations using integrated optical waveguides confirm record results

    Temperature aware power optimization for multicore floating-point units

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    High-Q Millimeter Wave RF Filters and Multiplexers

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    For a long period of time, millimeter waves (mm-Wave) were considered unsuitable for wireless data transmission due to high attention while propagating in the atmosphere. Over the past few years, due to the vigorous developments of multiple-in-multiple-out (MIMO) antenna technology and semiconductor technology, it is now feasible to have reliable wireless data transmissions using mm-Wave. Traditionally, mobile communication networks operate in the frequency spectrum under 6 GHz. In order to meet the ever-increasing demand for high communication data rate and high-quality multi-media services, the current fifth generation (5G) and the emerging 6G mobile communication systems will start to utilize the mm-Wave spectrum due to its bandwidth advantages, which in turn translates into a high data transmission rate. Millimeter-wave technology is also widely used in radar, imaging, medical therapy, and sensing applications. For those reasons, over the past few years, the interest in mm-Wave spectrum has significantly increased. RF filters are essential components in any communication systems to provide frequency selectivity. As the operating frequency of communication systems is extending to the mm-Wave spectrum, the conductor loss, the dielectric loss, and the radiation loss increase rapidly, which makes it challenging to develop high-Q mm-Wave filters. Three-dimensional (3D) waveguide filter structures exhibit excellent RF performance at mm-Wave frequencies and have been widely employed in high-performance RF systems. Nevertheless, as the operating frequency increases to mm-Wave frequency, the physical sizes of the waveguide filters become miniature in size impeding the use of post-fabricated tuning elements to compensate for the manufacturing tolerances of the traditional machining technologies. The silicon-micromachining technology has the potential to develop very accurate miniature 3D filters. This thesis focuses on the development of high-Q ultra-wideband mm-Wave planar filters using multilayer superconductor technology and 3D filter structures using silicon micromachining technology, making use of recent advances in deep reactive ions etching (DRIE) techniques. This thesis first introduces a new technique for filter design and tuning using the phase of the input impedance (PII) as the design parameter. This novel method is applicable to both narrow and wideband filters. Compared with conventional filter design and tuning methods, this approach requires less computation time and provides a clear step-by-step procedure for identifying the proper inter-resonator coupling and the resonant frequencies of the resonators. In practice, the physical realization of the filter always has a non-ideal I/O port, which can introduce an unexpected unknown transmission line between the physical reference plane and the port of the corresponding inverter in the circuit model. In this thesis, the PII response is used to determine the equivalent electrical length of this unknown transmission line. The validity of the proposed technique is demonstrated through the design of a wideband planar filter with a fractional bandwidth of 72%, the tuning of filters with transmission zeros and the design of a wideband diplexer. The multilayer superconductor technology allows to realize high-Q planar structures with highly miniature physical dimensions. The superconductor digital receivers can directly digitalize RF signals up to very high frequencies, eliminating the need to use mixers and oscillators to convert the RF signals to lower frequencies. This thesis demonstrates the feasibility of an ultra-wide band superconductor mm-Wave continuous triplexer that can be integrated with superconductor analog to digital converter (ADC) on a single niobium chip. A wideband high-Q mm-Wave highly miniature niobium-based superconductor multiplexer realized on an 8-layer niobium process has been developed, fabricated, and tested covering the frequency range 20 GHz - 80 GHz. In addition to monolithic integration of the superconductor multiplexer with the superconductor ADC, the thesis also demonstrates the feasibility of mounting the triplexer chip on a multi-chip-module (MCM) substrate using flip-chip technology interfaced with 1 mm mm-Wave connectors. This thesis also demonstrates using a unique behavior of spiral inductors designed intentionally to have a large parasitic capacitance in the realization of a tunable band reject filter. It is shown that, regardless of the operating frequency, the conductivity of the metal strips forming the inductor has a significant impact on how the spiral inductor behaves as an inductor or a capacitor. The concept is used to demonstrate a band reject filter made from a multilayer niobium circuit operating at 4 Kelvin. Such band reject filters are needed in the front-end of superconductor digital receivers to eliminate interference. Micromachining fabrication processes provide much higher manufacturing accuracy than traditional CNC machining technologies. Moreover, the DRIE silicon micromachining process is more economical for mass production and makes it possible to produce highly accurate 3D waveguide structures. This thesis presents filter designs composing of highly miniature silicon-micromachined ridge waveguide resonators. The proposed filter designs provide highly compact physical size with reasonable high Q values. An ultra-high-Q mm-Wave cavity filter employing a silicon-micromachined barrel-shape cavities operating in TE011 mode has been developed, fabricated and tested. The barrel-shape is proposed to realize a high-Q cavity, while circumventing the spurious issues of the degenerate TM modes that exist in traditional cylindrical-shape cavities. The filter was realized on silicon using DRIE techniques
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