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Journal ArticleDOI

Power and Area-Efficient Adaptive Equalization at Microwave Frequencies

08 Feb 2008-IEEE Transactions on Circuits and Systems I-regular Papers (IEEE)-Vol. 55, Iss: 6, pp 1412-1420
TL;DR: The proposed technique, which is term the lumped parameter equalizer, addresses several of the problems associated with conventional microwave equalizers based on the tapped delay line structure and is suitable for combating inter-symbol-interference at very high data rates.
Abstract: We present a low power analog adaptive equalization technique suitable for combating inter-symbol-interference at very high data rates. The proposed technique, which we term the lumped parameter equalizer, addresses several of the problems associated with conventional microwave equalizers based on the tapped delay line structure. The theory is given, and simulation results comparing it with the performance of ideal tapped delay line filters are shown. Circuit implementations are discussed, along with the effect of nonidealities on equalizer performance.
Citations
More filters
Journal ArticleDOI
TL;DR: A ladder filter-based programmable time-delay element for beamforming in ultra-wideband (UWB) systems and a lumped-element realization becomes possible by approximating e-std as a ratio of polynomials (based on Taylor and Padé expansions).
Abstract: We introduce a ladder filter-based programmable time-delay element for beamforming in ultra-wideband (UWB) systems. Such a lumped-element realization becomes possible by approximating e -std as a ratio of polynomials (based on Taylor and Pade expansions). When compared with conventional methods based on the tapped delay-line architecture, the proposed technique achieves lower power dissipation, higher delay range and resolution, and better area efficiency. A prototype delay line designed for the 3.1-10.6 GHz UWB range achieves a delay range of 140 ps and a gain range of -30 dB to +10 dB. Fabricated in a 0.25 μm SiGe BiCMOS process, the delay element occupies an active area of 1 mm 2 and consumes 53 mW from a 2.5 V supply. A four-antenna beamforming system using the delay element can achieve a scanning range of ±61 ° with 0.86 ° resolution for an antenna spacing of 15 mm.

23 citations


Additional excerpts

  • ...In this work, we exploit duality to efficiently sense inductor current [25]....

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Journal ArticleDOI
TL;DR: Through simulation it is shown that the effects of transmission line loss, uneven tap weight spacing and terminal impedance mismatch can be mitigated by properly adjusting the tap weights of the oscillator.
Abstract: This paper describes a type of distributed oscillator which combines the functions of distributed amplifiers (DAs), distributed transversal filters (DTFs), and distributed mixers (DMs). Nonlinear feedback of the kind used in mode-locked laser (MLL) systems is used in order to obtain phase locking between the resonant frequencies within the oscillator. The theory of operation is given and a tuning procedure for the tap weights of the distributed oscillator aimed at achieving a desired state of oscillation is presented. The impact that the nonideal components of the oscillator have on its performance is discussed. Through simulation it is shown that the effects of transmission line loss, uneven tap weight spacing and terminal impedance mismatch can be mitigated by properly adjusting the tap weights of the oscillator. Examples of waveform synthesis are given in which different periodic waveforms are produced by the oscillator including those found in an MLL and a waveform suitable for impulse based ultra-wideband systems.

10 citations


Cites background from "Power and Area-Efficient Adaptive E..."

  • ...The parasitics, losses, terminal impedance mismatch, and other nonideal characteristics inherent to distributed electronic components are known to affect their performance [16], [17]....

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Proceedings ArticleDOI
24 May 2015
TL;DR: This work presents a programmable pulse shaping filter based on singly-terminated LC ladders that by appropriate setting of the filter taps, a variety of shapes related to a Gaussian pulse can be generated.
Abstract: UWB pulse waveforms based on modified Hermite polynomials are spectrally efficient and mutually orthogonal. A reconfigurable generation of these UWB signals is a challenge. In this work, we present a programmable pulse shaping filter based on singly-terminated LC ladders. By appropriate setting of the filter taps, a variety of shapes related to a Gaussian pulse can be generated. Experimental results from a test chip designed in a 0.25 μm BiCMOS process are given.

7 citations


Cites methods from "Power and Area-Efficient Adaptive E..."

  • ...In this work, we use a dual ladder - this way, inductor currents in the original network are capacitor voltages in the dual - and can therefore be sensed using transconductors [10][11]....

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Proceedings ArticleDOI
11 Nov 2013
TL;DR: A ladder filter based programmable time delay element for beamforming in Ultra-Wideband (UWB) systems is introduced and achieves lower power dissipation, better area efficiency, and finer delay and gain resolution more efficiently.
Abstract: We introduce a ladder filter based programmable time delay element for beamforming in Ultra-Wideband (UWB) systems When compared to conventional methods based on the tapped delay line architecture, our technique achieves lower power dissipation, better area efficiency, and finer delay and gain resolution more efficiently The proposed architecture is more scalable, has better parasitic absorption capability and highly programmable with delay and gain resolution dependent only on transconductor resolution A prototype delay line designed for the 31-106 GHz UWB range achieves a delay range of 80 ps with 05 ps resolution and a gain range of -30 dB to +10 dB with 015 dB step Fabricated in a 025 μm SiGe BiCMOS process, the delay element occupies an active area of 1 mm2 and consumes 47 mW from a 25 V supply A four antenna beamforming system using the delay element can achieve scanning range of ± 51° with resolution of 086 ° for antenna spacing of 10 mm

6 citations


Cites methods from "Power and Area-Efficient Adaptive E..."

  • ...The efficacy of these techniques were demonstrated by measurements from a test chip....

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Proceedings ArticleDOI
24 May 2015
TL;DR: This work describes the working principle and design details of a low cost, on-chip monitor circuit that enables the determination of the eye diagram and demonstrates the efficacy of the techniques.
Abstract: Monitoring the eye diagram at the output of an embedded analog adaptive equalizer used in a high speed serial link is challenging. Eye measurement using an external oscilloscope is problematic due to the bandwidth of the test setup. In this work, we describe the working principle and design details of a low cost, on-chip monitor circuit that enables the determination of the eye diagram. The eye opening monitor (EOM), implemented in a 65 nm CMOS process, occupies 0.06 mm2 and consumes 5.7 mW from a 1.2 V supply. Measurements demonstrate the efficacy of our techniques.

1 citations


Cites methods from "Power and Area-Efficient Adaptive E..."

  • ...This has motivated the use of analog techniques for adaptive equalization - see for instance [1]....

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References
More filters
BookDOI
01 Jan 1986

2,843 citations


"Power and Area-Efficient Adaptive E..." refers methods in this paper

  • ...The implementation of the LMS algorithm involves the least amount of complexity if the state-signals (the signals that are being linearly combined) are explicitly available in the filter [14]....

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Journal ArticleDOI
01 Oct 1998
TL;DR: The topical decisions utilized in this tutorial can be used to help catalog the emerging literature on the CM criterion and on the behavior of (stochastic) gradient descent algorithms used to minimize it.
Abstract: This paper provides a tutorial introduction to the constant modulus (CM) criterion for blind fractionally spaced equalizer (FSE) design via a (stochastic) gradient descent algorithm such as the constant modulus algorithm (CMA). The topical decisions utilized in this tutorial can be used to help catalog the emerging literature on the CM criterion and on the behavior of (stochastic) gradient descent algorithms used to minimize it.

907 citations


"Power and Area-Efficient Adaptive E..." refers background in this paper

  • ...The optimal delay corresponds to the minimum diagonal element of [18]....

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Journal ArticleDOI
G. Ungerboeck1
TL;DR: It is shown that making the tap spacing of the equalizer somewhat smaller than T (fractional tap spacing) leads to satisfactory performance of theequalizer for a broad continuous range of clock phases, without penalizing the speed of convergence.
Abstract: Adaptive equalizers are usually realized in the form of a transversal filter with variable tap gains and tap spacing equal to the symbol spacing T . The performance of these equalizers depends critically on the symbol-clock phase derived in the receiver, due to the clock-phase dependent aliasing of the spectral roll-off components, upon which the conventional equalizer has no influence. In this paper we study the possibility of overcoming this difficulty by making the tap spacing of the equalizer somewhat smaller than T (fractional tap spacing). It is shown that this leads to satisfactory performance of the equalizer for a broad continuous range of clock phases, without penalizing the speed of convergence. Furthermore, it allows the application of a simple clock recovery scheme which derives a phase control signal from the equalizer tap-gain values.

309 citations


"Power and Area-Efficient Adaptive E..." refers background in this paper

  • ...The performance of an ideal symbol-spaced equalizer is sensitive to the timing-phase of the decision-device [12]....

    [...]

Book
01 Jan 1996
TL;DR: Digital Baseband Transmission and Recording provides an integral, in-depth and up-to-date overview of the signal processing techniques that are at the heart of digital baseband transmission and recording systems.
Abstract: From the Publisher: Digital Baseband Transmission and Recording provides an integral, in-depth and up-to-date overview of the signal processing techniques that are at the heart of digital baseband transmission and recording systems. The coverage ranges from fundamentals to applications in such areas as digital subscriber loops and magnetic and optical storage. Much of the material presented here has never before appeared in book form. The main features of Digital Baseband Transmission and Recording include: -- a survey of digital subscriber lines and digital magnetic and optical storage; -- a review of fundamental transmission and reception limits; -- an encyclopedic introduction to baseband modulation codes; -- development of a rich palette of equalization techniques; -- a coherent treatment of Viterbi detection and many near-optimum detection schemes; -- an overview of adaptive reception techniques that encompasses adaptive gain and slope control, adaptive detection, and novel forms of zero-forcing adaptation; -- an in-depth review of timing recovery and PLLs, with an extensive catalog of timing-recovery schemes. Featuring around 450 figures, 200 examples, 350 problems and exercises, and 750 references, Digital Baseband Transmission and Recording is an essential reference source to engineers and researchers active in telecommunications and digital recording. It will also be useful for advanced courses in digital communications.

284 citations


"Power and Area-Efficient Adaptive E..." refers methods in this paper

  • ...On the other hand, deductive timing recovery techniques [13] (those that use the output of the TIA/VGA or the equalizer in Fig....

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Journal ArticleDOI
TL;DR: In this paper, a seven-tap distributed transversal equalizer prototype has been implemented in a commercial 0.18/spl mu/m SiGe BiCMOS process for 10-Gb/s multimode fiber-optic links.
Abstract: Intersymbol interference (ISI) caused by intermodal dispersion in multimode fibers is the major limiting factor in the achievable data rate or transmission distance in high-speed multimode fiber-optic links for local area networks applications. Compared with optical-domain and other electrical-domain dispersion compensation methods, equalization with transversal filters based on distributed circuit techniques presents a cost-effective and low-power solution. The design of integrated distributed transversal equalizers is described in detail with focus on delay lines and gain stages. This seven-tap distributed transversal equalizer prototype has been implemented in a commercial 0.18-/spl mu/m SiGe BiCMOS process for 10-Gb/s multimode fiber-optic links. A seven-tap distributed transversal equalizer reduces the ISI of a 10-Gb/s signal after 800 m of 50-/spl mu/m multimode fiber from 5 to 1.38 dB, and improves the bit-error rate from about 10/sup -5/ to less than 10/sup -12/.

163 citations


"Power and Area-Efficient Adaptive E..." refers background or methods in this paper

  • ...For example, each delay cell used in the traveling-wave equalizer reported in [3] is approximately 220 m across....

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  • ...motivation for using microwave techniques to realize FIR filters in the analog domain, as evidenced in several recent publications [3]–[10]....

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