A Sideband-separating Receiver with a Calibrated Digital If-Hybrid Spectrometer for the Millimeter Band

Rodríguez, Rafael; Finger, Ricardo; Mena, F. P.; Reyes, Nicolás; Ernest, Michael; Bronfman, L.

doi:10.1086/676307

Cited by 12 publications

(11 citation statements)

References 8 publications

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“…Most recently this concept has also been applied to the millimeter band achieving sideband-rejection ratios greater than 35 dB. 9 In this article we extend this later work by demonstrating that it can also be applied to receivers that incorporate a second down-conversion stage. The rest of the article is structured as follows.…”

Section: Introductionmentioning

confidence: 68%

“…In this way, the constants C1 to C4 (see Figure 1b) are obtained. 8,9 This calibration must be performed every time LO1 or LO2 frequencies or power are changed (see Figure 1a). To measure the image rejection ratio one can either apply the procedure described in Reference 13 or introduce two signals at different RF sidebands producing the same IF frequency.…”

Section: Methodsmentioning

confidence: 99%

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A digital sideband-separating receiver for the millimeter band

et al. 2014

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Sideband-separating receivers are usually preferred in the presence of high atmospheric noise. However, one of the most important figures of merit for this kind of receiver, the sideband ratio, is still low and typically around 10 dB. This is because keeping low amplitude and phase imbalances over large RF and IF frequencies is extremely difficult. However, by introducing a digital back-end that mimics the performance of an IF-hybrid, such imbalances can be calibrated out. We have recently presented a digital sideband-separating receiver, working at the W band, that can achieve sideband ratios well above 35 dB. Here we extend this work by demonstrating that it can also be applied to receivers that incorporate a second down-conversion stage with the same performance.

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Section: Introductionmentioning

confidence: 68%

Section: Methodsmentioning

confidence: 99%

A digital sideband-separating receiver for the millimeter band

et al. 2014

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“…We have implemented the SRR-compensation scheme on a fully analog Band-9 2SB prototype receiver of ALMA (Hesper et al 2016;Khudchenko et al 2017) using a FPGA-based digital spectrometer (Finger et al 2013;Rodríguez et al 2014b;Finger et al 2015). This receiver uses superconductor-insulator-superconductor (SIS) junctions as mixers and operates in the RF band of 602 to 720 GHz with the standard ALMA IF frequency range, 4-12 GHz.…”

Section: Methodsmentioning

confidence: 99%

Digital compensation of the sideband-rejection ratio in a fully analog 2SB sub-millimeter receiver

Rodríguez

Finger

Mena

et al. 2018

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Context. In observational radio astronomy, sideband-separating receivers are preferred, particularly under high atmospheric noise, which is usually the case in the sub-millimeter range. However, obtaining a good rejection ratio between the two sidebands is difficult since, unavoidably, imbalances in the different analog components appear.Aims. We describe a method to correct these imbalances without making any change in the analog part of the sideband-separating receiver, specifically, keeping the intermediate-frequency hybrid in place. This opens the possibility of implementing the method in any existing receiver.Methods. (i) We have built hardware to demonstrate the validity of the method and tested it on a fully analog receiver operating between 600 and 720 GHz. (ii) We have tested the stability of calibration and performance versus time and after full resets of the receiver. (iii) We have performed an error analysis to compare the digital compensation in two configurations of analog receivers, with and without intermediate frequency (IF) hybrid.Results. (i) An average compensated sideband rejection ratio of 46 dB is obtained. (ii) Degradation of the compensated sideband rejection ratio on time and after several resets of the receiver is minimal. (iii) A receiver with an IF hybrid is more robust to systematic errors. Moreover, we have shown that the intrinsic random errors in calibration have the same impact for configuration without IF hybrid and for a configuration with IF hybrid with analog rejection ratio better than 10 dB.Conclusions. We demonstrate that compensated rejection ratios above 40 dB are obtained even in the presence of high analog rejection. Further, we demonstrate that the method is robust allowing Article number, page 1 of 11 arXiv:1806.04053v1 [eess.SP] 11 Jun 2018 R. Rodriguez et al.: Digital rejection compensation in a 2SB sub-millimeter receiver.its use under normal operational conditions at any telescope. We also demonstrate that a full analog receiver is more robust against systematic errors. Finally, the error bars associated to the compensated rejection ratio are almost independent of whether IF hybrid is present or not.

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“…In a sideband separating receiver, DFTs may take over the function of the IFhybrid, thereby simplifying the mixer hardware [108]. The IF-hybrid functionality is implemented digitally by a properly phased sampling and combination of the output signals of the two mixers.…”

Section: If-processing and Backendsmentioning

confidence: 99%

Terahertz Heterodyne Array Receivers for Astronomy

Graf

Honingh

Jacobs

et al. 2015

J Infrared Milli Terahz Waves

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We review the development of multi-pixel heterodyne receivers for astronomical research in the submillimeter and terahertz spectral domains. We shortly address the historical development, highlighting a few pioneering instruments. A discussion of the design concepts is followed by a presentation of the technologies employed in the various receiver subsystems and of the approaches taken to optimize these for current and future instruments.

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A Sideband-separating Receiver with a Calibrated Digital If-Hybrid Spectrometer for the Millimeter Band

Cited by 12 publications

References 8 publications

A digital sideband-separating receiver for the millimeter band

A digital sideband-separating receiver for the millimeter band

Digital compensation of the sideband-rejection ratio in a fully analog 2SB sub-millimeter receiver

Terahertz Heterodyne Array Receivers for Astronomy

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