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Gabriel M Rebeiz - One of the best experts on this subject based on the ideXlab platform.

  • a packaged 0 01 26 ghz single chip sige reflectometer for two port vector network analyzers
    IEEE Transactions on Microwave Theory and Techniques, 2020
    Co-Authors: Hyunchul Chung, Mustafa Sayginer, Gabriel M Rebeiz
    Abstract:

    This article presents a packaged SiGe BiCMOS reflectometer for 0.01–26-GHz two-port vector network analyzers (VNAs). The reflectometer chip is composed of a resistive bridge coupler and two wideband Heterodyne Receivers for coherent magnitude and phase detection. In addition, a high-linearity receiver channel is designed to accommodate ~20 dBm of RF input power to the reflectometer. External sources are used to provide stimulus over the entire bandwidth, and a high-linearity shunt 50- $\Omega $ switch is placed at the input of each reflectometer chip to provide a matched condition for better measurement accuracy. The measured dynamic range (DR) of the Heterodyne receiver is 129±3 dB at 0.01–26 GHz at an IF resolution bandwidth (RBW) of 10 Hz. The reflectometer chip is packaged on a low-cost printed circuit board (PCB) and connectorized for repeatable measurements. Several passive and active device-under-test (DUTs), such as filters and amplifiers, are measured in single- and dual-port complex $S$ -parameter setup at 0.01–26 GHz. The single-chip reflectometer results in excellent agreement with commercially available test equipment and with minimal magnitude and phase difference. Several definitions (mean deviation and error vector) are used to quantify the measurement accuracy. A measured $S_{21}$ of −80 dB is obtained using high-rejection filters. An in-depth DR analysis of possible limiting factors in the measurement setup is also presented. This article shows that silicon-based highly integrated reflectometers can be used in low-cost VNAs with excellent DR and accuracy.

  • a 0 01 26 ghz single chip sige reflectometer for two port vector network analyzers
    International Microwave Symposium, 2017
    Co-Authors: Hyunchul Chung, Mustafa Sayginer, Gabriel M Rebeiz
    Abstract:

    This paper presents a single-chip 0.01–26 GHz reflectometer for two-port vector network analyzers (VNA). The reflectometer consists of a bridge coupler integrated together with two wideband Heterodyne Receivers. For wideband operation, a resistive bridge coupler is used with a directivity of 33 dB up to 26 GHz. Also, a high-linearity receiver channel is designed so as to accommodate 10 dBm of RF input power to the reflectometer. The SiGe chip is 1.8 mm2 and consumes 640 mW from a 3.3 V supply. The dynamic range of the reflectometer chip is 127±2 dB at 0.01–26 GHz with an IF resolution bandwidth (RBW) of 10 Hz. The chip is placed on a printed circuit board (PCB), and RF, LO and DC bias are connecterized. Measurements of several device-under-test units (DUTs) with a two-port 0.01–26 GHz VNA composed of two reflectometer chips shows excellent agreement with a commercial VNA, with a magnitude and phase difference of 21 as well as minimal magnitude and phase difference compared to state-of-the-art VNA measurements.

  • a 70 110 ghz single chip sige reflectometer with integrated local oscillator quadrupler
    International Microwave Symposium, 2017
    Co-Authors: Hyunchul Chung, Gabriel M Rebeiz
    Abstract:

    This paper presents a 70–110 GHz single-chip SiGe reflectometer for one-port vector network analyzer (VNA). Two directional couplers are implemented together with two high-linearity Heterodyne Receivers on a single chip at 70–110 GHz. In addition, a x4 frequency multiplier chain is also implemented on the same chip. A CPW (Coplanar Waveguide) coupled-line directional is used with a shielded gound plane for improved isolation and directivity. The dynamic range of the receiver is 110–115 dB at 70–110 GHz with 10 dB back-off and 10 Hz resolution bandwidth (RBW). The SiGe chip is 5.86 mm2 and consumes 440 mW from a 2 V supply. The chip is mounted on a printed circuit board (PCB), and RF and LO signals are applied using probes. A 95 GHz bandpass filter is measured as the device-under-test (DUT) and the results obtained using the on-chip VNA and a commericial VNA show good agreement over a wide frequency range.

Murat Uysal - One of the best experts on this subject based on the ideXlab platform.

  • Multi-Hop Coherent Free-Space Optical Communications over Atmospheric Turbulence Channels
    2016
    Co-Authors: Sahar Molla Aghajanzadeh, Murat Uysal, Student Member, Senior Member
    Abstract:

    Abstract—In this paper, we investigate multi-hop relaying as an efficient fading mitigation tool for coherent free-space optical (FSO) systems over atmospheric turbulence channels. We consider an FSO relaying system with decode-and-forward relay nodes and multiple Heterodyne Receivers with modal compensa-tion. Based on a recently introduced statistical characterization for the combined effects of log-normal turbulence fading and modal compensation, we derive the outage probability and quantify the potential performance improvements through the derivation of diversity-multiplexing tradeoff (DMT) and diversity gain. Our outage analysis yields impressive power savings for multi-hop relaying even with a single-relay. In addition, the DMT analysis in practical signal-to-noise ratio (SNR) ranges demon-strates that multi-hop transmission scheme improves finite-SNR diversity gain throughout the range of the multiplexing gain. Index Terms—Free-space optical systems, multi-hop trans-mission, finite-SNR diversity-multiplexing tradeoff, atmospheric turbulence-induced fading. I

  • multi hop coherent free space optical communications over atmospheric turbulence channels
    IEEE Transactions on Communications, 2011
    Co-Authors: Sahar Molla Aghajanzadeh, Murat Uysal
    Abstract:

    In this paper, we investigate multi-hop relaying as an efficient fading mitigation tool for coherent free-space optical (FSO) systems over atmospheric turbulence channels. We consider an FSO relaying system with decode-and-forward relay nodes and multiple Heterodyne Receivers with modal compensation. Based on a recently introduced statistical characterization for the combined effects of log-normal turbulence fading and modal compensation, we derive the outage probability and quantify the potential performance improvements through the derivation of diversity-multiplexing tradeoff (DMT) and diversity gain. Our outage analysis yields impressive power savings for multi-hop relaying even with a single-relay. In addition, the DMT analysis in practical signal-to-noise ratio (SNR) ranges demonstrates that multi-hop transmission scheme improves finite-SNR diversity gain throughout the range of the multiplexing gain.

F Joint - One of the best experts on this subject based on the ideXlab platform.

  • compact and sensitive Heterodyne receiver at 2 7 thz exploiting a quasi optical heb qcl coupling scheme
    Applied Physics Letters, 2019
    Co-Authors: F Joint, Pierrebaptiste Vigneron, T Vacelet, Stefano Pirotta, R Lefevre, Y Jin, A G Davies, E H Linfield, Y Delorme
    Abstract:

    We demonstrate a sensitive and compact terahertz Heterodyne detection system based on a quantum cascade laser (QCL) as a local oscillator and a hot electron bolometer (HEB) as a mixer. It relies on an original optical coupling scheme where the terahertz (THz) signal to be detected and the local oscillator (LO) signal are coupled to the HEB from both sides of the integrated lens/antenna mixer. The THz signal of interest impinges on the front side through the silicon lens while the LO onto the rear (air) side. This concept allows us to remove the beam splitter usually employed in terahertz Heterodyne Receivers. The mixer consists of a Niobium Nitride HEB with a log-spiral planar antenna mounted on the flat side of a hyperhemispherical silicon lens. The local oscillator of the Heterodyne detector is a low power consumption and low beam divergence 3rd-order distributed feedback laser with single mode emission at the target frequency of 2.7 THz. The coupling between the QCL and the HEB has been further optimized, using a dielectric hollow waveguide that reliably increases the laser beam directivity and permits us to pump the HEB into its most sensitive state through the air side of the planar antenna. We have measured a noncorrected double sideband receiver noise temperature of 880 K at 2.7 THz.

W R Mcgrath - One of the best experts on this subject based on the ideXlab platform.

  • tunable antenna coupled intersubband terahertz tacit mixers the quantum limit without the quantum liquid
    arXiv: Instrumentation and Detectors, 2019
    Co-Authors: M S Sherwin, C L Cates, B Serapiglia, Y Dora, J B Williams, K D Maranowski, A C Gossard, W R Mcgrath
    Abstract:

    At present, nearly quantum-limited Heterodyne Receivers for Terahertz (THz) frequencies require cooling to temperatures below 4K. We are working to build semiconductor-based "tunable antenna-coupled intersubband terahertz" (TACIT) Heterodyne mixers for 1-5 THz. We predict that they can achieve single-sideband noise temperatures of a few hundred K with intermediate frequency (IF) bandwidth >10 GHz, while operating at lattice temperatures >20 K and requiring local oscillator (LO) power ~ 1 $\mu$W.

  • mixing and noise in diffusion and phonon cooled superconducting hot electron bolometers
    Journal of Applied Physics, 1999
    Co-Authors: Peter Burke, W R Mcgrath, R J Schoelkopf, D E Prober, A Skalare, B Bumble, B S Karasik, Michael C Gaidis, H G Leduc
    Abstract:

    We report a systematic, comprehensive set of measurements on the dynamics and noise processes in diffusion and phonon-cooled superconducting hot-electron bolometer mixers which will serve as ultralow noise detectors in THz Heterodyne Receivers. The conversion efficiency and output noise of devices of varying lengths were measured with radio frequency between 8 and 40 GHz. The devices studied consist of 100-A-thin film Nb bridges connected to thick (1000 A), high conductivity normal metal (Au) leads. The lengths of the devices studied range from 0.08 to 3 μm. For devices longer than the electron–phonon interaction length Le–ph≡Dτe–ph, with D the diffusion constant and τe–ph−1 the electron–phonon interaction rate, the hot electrons are cooled dominantly by the electron–phonon interaction, which in Nb is too slow for practical applications. If the device length is less than πLe–ph(≈1 μm at 4.2 K), then out diffusion of heat into the high conductivity leads dominates the cooling process. In this limit, the in...

  • length scaling of bandwidth and noise in hot electron superconducting mixers
    Applied Physics Letters, 1996
    Co-Authors: Peter Burke, W R Mcgrath, R J Schoelkopf, D E Prober, A Skalare, B Bumble, H G Leduc
    Abstract:

    Mixing experiments have been performed at frequencies from 4 to 20 GHz on Nb thin‐film superconducting hot‐electron bolometers varying in length from 0.08 to 3 μm. The intermediate frequency (IF) bandwidth is found to vary as L−2, with L the bridge length, for devices shorter than √12 Le−ph≊1 μm, with Le−ph the electron‐phonon length. The shortest device has an IF bandwidth greater than 6 GHz, the largest reported for a low‐Tc superconducting bolometric mixer. The conversion efficiencies range from −5 to −11 dB (single sideband, SSB). For short bridges, the mixer noise temperature is found to be as low as 100 K (double sideband, DSB), with little length dependence. The local oscillator power required is small, ≊10 nW. Such mixers are very promising for low‐noise THz Heterodyne Receivers.

Hercules Avramopoulos - One of the best experts on this subject based on the ideXlab platform.

  • Bandpass sampling in Heterodyne Receivers for coherent optical access networks
    Optics express, 2012
    Co-Authors: Paraskevas Bakopoulos, Stefanos Dris, B. Schrenk, I. Lazarou, Hercules Avramopoulos
    Abstract:

    A novel digital receiver architecture for coherent Heterodyne-detected optical signals is presented. It demonstrates the application of bandpass sampling in an optical communications context, to overcome the high sampling rate requirement of conventional Receivers (more than twice the signal bandwidth). The concept is targeted for WDM coherent optical access networks, where applying Heterodyne detection constitutes a promising approach to reducing optical hardware complexity. The validity of the concept is experimentally assessed in a 76 km WDM-PON scenario, where the developed DSP achieves a 50% ADC rate reduction with penalty-free operation.