A Photonic Analog-to-Digital Converter Based on an Unbalanced Mach-Zehnder Quantizer

Sarantos, Chris H.; Dagli, N.

doi:10.1109/mwp.2007.4378135

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…Among them, synchronization is the core functionality of communication systems, especially for the THz high‐speed communication system [ 6 ] . The large bandwidth characteristic of the signal makes it difficult for the Analog‐digital‐converters (ADCs) as well as Digital‐analog‐converters (DACs) to reach the Nyquist sampling rate while maintaining a high quantization bit number [ 7 , 8 ] . Furthermore, the accuracy of both ADCs and DACs deteriorates drastically at very high sampling rates, making it unsuitable for high‐order modulation.…”

Section: Introductionmentioning

confidence: 99%

A Novel Synchronization Method in Terahertz Large‐Scale Antenna Array System

Zheng¹,

Ding²,

Liu³

et al. 2021

Chinese J of Electronics

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We focus on the problems of the accurate time delay estimation, the design of training pilots, and hybrid matrix optimization within the large‐scale antenna array Terahertz (THz) broadband communication system. In contrast to the existing researches based on narrow‐band arrays, we hereby shed light on the time delay estimation of broadband arrays. In THz broadband communication systems, the data symbol duration is relatively short when comparing with the dimension of the antenna array. In large‐scale antenna systems, signals received in each antenna are no longer different phase‐shifted copies of the same symbol, but completely different symbols in which occasion traditional narrow‐band structure is no longer suitable. Based on the above conclusion, firstly, we put forward a system model based on large‐scale antenna arrays and Time delay line (TDL) structure. Secondly, we deduce the Cramer‐Rao lower bound (CRLB) of the time delay estimation, and present a time delay estimation algorithm that could reach the CRLB. Thirdly, by minimizing the CRLB, we address the design of the training pilot and optimized TDL structure under the condition of constant envelope training pilot and modulus TDL structure. Finally, we disclose the numerical simulation results. According to the simulation results, the aforementioned method is workable in reaching the CRLB, the TDL structure can significantly surpass that of the traditional model, and the optimal pilot design method outperforms the pseudo‐random pilot structure.

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Section: Introductionmentioning

confidence: 99%

A Novel Synchronization Method in Terahertz Large‐Scale Antenna Array System

Zheng¹,

Ding²,

Liu³

et al. 2021

Chinese J of Electronics

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“…In the past several decades, many ADC schemes with the help of photonic technologies have been proposed. Typical schemes include the techniques of photonic sampling and electronic digitizing [6,7], the technique of photonic time stretch for preprocessing signals prior to electronic quantization [8,9], the approaches based on amplitude-to-frequency conversion using optical nonlinearities [10,11], and the photonic digitization schemes using Mach-Zehnder interferometers (MZIs) or Mach-Zehnder modulators (MZMs) [12][13][14][15][16][17][18], as well as others [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…Since this approach avoids the difficulty relating to V  scaling as in Taylor's approach, the concept of phase-shifting photonic digitization (PSPD) has attracted a great deal of attention. Up to now a number of PSPD schemes have been proposed, such as the approach using a PM and polarization interferometric phase shifters [14], the scheme using properly biased MZMs with identical V  [15], the differential encoding scheme using a single PM and delay line interferometers [16], the approach using an unbalanced MZM [17], and so on [18]. Although the PSPD schemes avoid the geometrical scaling of V  , the realized quantization levels are relatively low, which is 2N for a system with N channels but not 2 N as in Taylor's scheme.…”

Section: Introductionmentioning

confidence: 99%

A Photonic Digitization Scheme With Enhanced Bit Resolution Based on Hierarchical Quantization

et al. 2020

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The major limitation of the photonic digitization schemes based on the phase-shifting of modulation transfer function lies in its relatively low bit resolution, which is log2(2N), where N is the number of optical channels or modulators. In this paper, we propose a novel photonic digitization scheme based on hierarchical quantization, which could greatly improve the system resolution with a relatively simple configuration. It is shown that 6N quantization levels, can be realized by using only three Mach-Zehnder modulators (MZMs) and a hierarchical quantization module (HQM) in the proposed scheme. By adjusting the fine quantization module inside HQM, the system resolution can be enhanced greatly. A proof-of-concept experiment is implemented, which fully verifies the correctness of the approach. Since simpler configuration and higher resolution are achieved, the proposed scheme provides a promising solution for high-performance photonic analog-to-digital conversion.INDEX TERMS analog-to-digital conversion, hierarchical quantization, ENOB.

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“…Another scheme of PSPD is to use parallel intensity modulators with optical attenuation [20], which achieves the desired phase shifts by controlling the modulated signal intensity. In addition, the PSPD schemes can also be realized by using a single MZM with a fiber stretcher array [21] or based on a special designed MZM (i.e., unbalanced MZM) [22].…”

Section: Introductionmentioning

confidence: 99%

Photonic Digitization With Differential Encoding Based on Orthogonal Vector Superposition

et al. 2019

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In this paper a novel photonic digitization scheme with differential encoding based on orthogonal vector superposition (OVS) is proposed and demonstrated. A phase modulator (PM) and two delay-line interferometers (DLIs) with π/2 difference in bias phase are employed to generate two orthogonal modulated signals. By adjusting and combining the intensity of two orthogonal signals with an OVS module, the desired phase shifts among different transfer functions can be obtained. The proposed scheme can differentially encode the input signal with enhanced bit resolution. Compared with the existing photonic digitization schemes based on modulators, this scheme features its simple configuration, because only a single PM, two DLIs and an OVS module are required; moreover, since the desired phase shifts of transfer functions are realized by attenuating the signal intensities, the proposed scheme can effectively alleviate the problem of phase bias drift induced by modulators. Proof-of-concept experiments of 3-and 4-bit photonic digitization systems based on OVS are successfully carried out, which demonstrate the feasibility of the approach.

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A Photonic Analog-to-Digital Converter Based on an Unbalanced Mach-Zehnder Quantizer

Cited by 4 publications

References 11 publications

A Novel Synchronization Method in Terahertz Large‐Scale Antenna Array System

A Novel Synchronization Method in Terahertz Large‐Scale Antenna Array System

A Photonic Digitization Scheme With Enhanced Bit Resolution Based on Hierarchical Quantization

Photonic Digitization With Differential Encoding Based on Orthogonal Vector Superposition

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