Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909504
Suguru Habu, Y. Yamao, H. Suzuki
A novel digital predistortion (DPD) architecture for amplitude- and phase- weighted beamforming (BF) transmitter is proposed. Based on the analysis of BF nonlinear radiation characteristics over-the-air, the proposed DPD with a simple unified feedback circuit can reduce nonlinear radiation in every direction. The performance of proposed DPD is evaluated through computer simulation assuming Chebyshev-weighed BF arrays. The results show that the proposed architecture can suppress nonlinear radiation to less than -45 dB in all direction, which is similar to the full DPD architecture that requires individual feedback circuit for each antenna element.
{"title":"Unified Feedback Beamforming Digital Predistorter","authors":"Suguru Habu, Y. Yamao, H. Suzuki","doi":"10.23919/EuMIC.2019.8909504","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909504","url":null,"abstract":"A novel digital predistortion (DPD) architecture for amplitude- and phase- weighted beamforming (BF) transmitter is proposed. Based on the analysis of BF nonlinear radiation characteristics over-the-air, the proposed DPD with a simple unified feedback circuit can reduce nonlinear radiation in every direction. The performance of proposed DPD is evaluated through computer simulation assuming Chebyshev-weighed BF arrays. The results show that the proposed architecture can suppress nonlinear radiation to less than -45 dB in all direction, which is similar to the full DPD architecture that requires individual feedback circuit for each antenna element.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122662333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909420
Yuan Tao, Z. Hu, Yong Fan, Ya Nan Liu, M. He, Y. Cheng, Bo Zhang
Multi-bias measured and simulated S parameters are presented to validate the extension of an accurate on/off state HEMT switch small-signal modelling procedure to analog attenuator applications. Good agreements between measured and simulated multi-bias S parameters of the HEMT with a gate resistor are achieved by using only a common-gate real test-structure (without the gate resistor), which not only confirm the validity of the modelling for both digital and analog attenuator applications, but also validate the applicability of the capacitance network and extraction methods under more bias conditions.
{"title":"HEMT Small-Signal Modelling for Voltage-Controlled Attenuator Applications","authors":"Yuan Tao, Z. Hu, Yong Fan, Ya Nan Liu, M. He, Y. Cheng, Bo Zhang","doi":"10.23919/EuMIC.2019.8909420","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909420","url":null,"abstract":"Multi-bias measured and simulated S parameters are presented to validate the extension of an accurate on/off state HEMT switch small-signal modelling procedure to analog attenuator applications. Good agreements between measured and simulated multi-bias S parameters of the HEMT with a gate resistor are achieved by using only a common-gate real test-structure (without the gate resistor), which not only confirm the validity of the modelling for both digital and analog attenuator applications, but also validate the applicability of the capacitance network and extraction methods under more bias conditions.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116711890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909549
N. Subramani, M. Bouslama, R. Sommet, J. Nallatamby
In this work, traps induced drain-lag dispersion mechanism of GaN/AlGaN/GaN HEMT grown on SiC substrate is investigated through time domain drain lag measurement and TCAD-based physical device simulations. The transient variation of the drain current owing to applied drain turn-on voltage pulses have been examined. Furthermore, TCAD physical simulations have been performed by introducing traps in various regions of the device, in order to identify the physical location of traps causing drain-lag mechanism. The simulation results validate that acceptor-like traps existing in the GaN buffer are responsible for the drain-lag effect observed in measurement.
{"title":"Time Domain Drain Lag Measurement and TCAD-based Device Simulations of AlGaN/GaN HEMT: Investigation of Physical Mechanism","authors":"N. Subramani, M. Bouslama, R. Sommet, J. Nallatamby","doi":"10.23919/EuMIC.2019.8909549","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909549","url":null,"abstract":"In this work, traps induced drain-lag dispersion mechanism of GaN/AlGaN/GaN HEMT grown on SiC substrate is investigated through time domain drain lag measurement and TCAD-based physical device simulations. The transient variation of the drain current owing to applied drain turn-on voltage pulses have been examined. Furthermore, TCAD physical simulations have been performed by introducing traps in various regions of the device, in order to identify the physical location of traps causing drain-lag mechanism. The simulation results validate that acceptor-like traps existing in the GaN buffer are responsible for the drain-lag effect observed in measurement.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127306252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909397
Pramod K. Singh, K. Suman, Santosh K Gedela, Kishore Bantupalli, K. Y. Varma, R. Gongo
Very high output power level is achieved at microwave frequencies using Gallium Nitride technologies due to high breakdown voltage, high current density and high carrier mobility in AlGaN/GaN based High Electron Mobility Transistors. The specific 0.45 $mu$m AlGaN/GaN on SiC HEMT based MMIC technology is developed for this purpose to operate at high DC bias voltage of 50 V to achieve high power at microwave frequencies. This paper demonstrates that a high microwave power exceeding 100 W can be achieved from a single MMIC chip fully matched to 50 Ohm at S-band frequencies. In addition to high power, high power added efficiency greater than 50% is also achieved in this chip. The implemented high-power amplifier chip is a two-stage amplifier achieving output power greater than 50 dBm with power gain better than 22 dB, and power added efficiency exceeding 50% over frequency range of 3.1-3.5 GHz. The MMIC chip layout area is as compact as 5.8 $times$ 3.3 mm2. The saturated output power density of transistor in this chip reaches value of 7 W/mm, maximum possible in this technology.
{"title":"100 W High Power Amplifier MMIC in 0.45 μm GaN Technology","authors":"Pramod K. Singh, K. Suman, Santosh K Gedela, Kishore Bantupalli, K. Y. Varma, R. Gongo","doi":"10.23919/EuMIC.2019.8909397","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909397","url":null,"abstract":"Very high output power level is achieved at microwave frequencies using Gallium Nitride technologies due to high breakdown voltage, high current density and high carrier mobility in AlGaN/GaN based High Electron Mobility Transistors. The specific 0.45 $mu$m AlGaN/GaN on SiC HEMT based MMIC technology is developed for this purpose to operate at high DC bias voltage of 50 V to achieve high power at microwave frequencies. This paper demonstrates that a high microwave power exceeding 100 W can be achieved from a single MMIC chip fully matched to 50 Ohm at S-band frequencies. In addition to high power, high power added efficiency greater than 50% is also achieved in this chip. The implemented high-power amplifier chip is a two-stage amplifier achieving output power greater than 50 dBm with power gain better than 22 dB, and power added efficiency exceeding 50% over frequency range of 3.1-3.5 GHz. The MMIC chip layout area is as compact as 5.8 $times$ 3.3 mm2. The saturated output power density of transistor in this chip reaches value of 7 W/mm, maximum possible in this technology.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129554791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909647
O. Jardel, Manuel Potércau, V. M. Leal, S. Rochette, J. Prades, A. Ghiotto, H. Leblond, N. Deltimple, J. Villemazet
This paper presents the design, implementation and characterizations of a Ka-Band [17.3 - 20.2 GHz] linearized channel amplifier (LCAMP) for space Travelling Wave Tube Amplifier (TWTA). The 130nm SiGe BiCMOS technology from ST Microelectronics (BiCMOS9MW) has been used. It validates the feasibility of a LCAMP and all its constitutive building blocks in silicon technologies at such high frequencies with high linearity requirements, hence allowing to consider a drastic mass, footprint and cost reduction of such equipment.
{"title":"Feasibility Demonstration of a Ka-Band Linearized Channel Amplifier in Silicon Technology for Space Applications","authors":"O. Jardel, Manuel Potércau, V. M. Leal, S. Rochette, J. Prades, A. Ghiotto, H. Leblond, N. Deltimple, J. Villemazet","doi":"10.23919/EuMIC.2019.8909647","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909647","url":null,"abstract":"This paper presents the design, implementation and characterizations of a Ka-Band [17.3 - 20.2 GHz] linearized channel amplifier (LCAMP) for space Travelling Wave Tube Amplifier (TWTA). The 130nm SiGe BiCMOS technology from ST Microelectronics (BiCMOS9MW) has been used. It validates the feasibility of a LCAMP and all its constitutive building blocks in silicon technologies at such high frequencies with high linearity requirements, hence allowing to consider a drastic mass, footprint and cost reduction of such equipment.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"710 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122001029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909589
R. Giofré, F. Costanzo, M. Sotgia, M. Cirillo, E. Limiti
This paper presents the experimental results of a monolithic microwave integrated circuit (MMIC) high power amplifier (HPA) in Gallium Nitride (GaN) technology conceived for S-Band active electronically scanned array systems. The MMIC is based on a three-stage architecture and it is realized in a commercially available $0.25 mu m$ GaN process. The HPA provides an output power higher than 50W with an associated gain and a power added efficiency greater than 34dB and 50%, respectively, in a fractional bandwidth larger than 15%. The overall chip area is limited to 6x5.4 mm2.
{"title":"A GaN MMIC HPA with 50W Output Power and 50% PAE for S-Band Radar Systems","authors":"R. Giofré, F. Costanzo, M. Sotgia, M. Cirillo, E. Limiti","doi":"10.23919/EuMIC.2019.8909589","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909589","url":null,"abstract":"This paper presents the experimental results of a monolithic microwave integrated circuit (MMIC) high power amplifier (HPA) in Gallium Nitride (GaN) technology conceived for S-Band active electronically scanned array systems. The MMIC is based on a three-stage architecture and it is realized in a commercially available $0.25 mu m$ GaN process. The HPA provides an output power higher than 50W with an associated gain and a power added efficiency greater than 34dB and 50%, respectively, in a fractional bandwidth larger than 15%. The overall chip area is limited to 6x5.4 mm2.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127669865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909451
G. Avolio, A. Raffo, M. Marchetti, G. Bosi, V. Vadalà, G. Vannini
We compared two approaches to use high-frequency transistor load-pull data directly into a circuit simulator. One approach is based on Artificial Neural Networks (ANN), the other on look-up tables (LUT). We discuss some practical aspects, including implementation in the CAD environment and extrapolation capability.
{"title":"GaN FET Load-Pull Data in Circuit Simulators: a Comparative Study","authors":"G. Avolio, A. Raffo, M. Marchetti, G. Bosi, V. Vadalà, G. Vannini","doi":"10.23919/EuMIC.2019.8909451","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909451","url":null,"abstract":"We compared two approaches to use high-frequency transistor load-pull data directly into a circuit simulator. One approach is based on Artificial Neural Networks (ANN), the other on look-up tables (LUT). We discuss some practical aspects, including implementation in the CAD environment and extrapolation capability.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124428555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909640
S. Guerrieri, F. Bonani, G. Ghione
The active device X-parameters extracted from physics-based TCAD simulations are imported into the Keysight ADS environment following the techniques outlined in [1], leading to an efficient, yet physically sound, circuit-level nonlinear model, retaining a direct link with the device fabrication technology. In this work, the X parameter model is used to demonstrate that a fully statistical analysis of a nonlinear circuit as a function of technological spread of the active device can be efficiently carried out within ADS, with extremely reduced simulation time and excellent agreement with the original TCAD analysis. As a test case, we address the statistical analysis of a deep class AB amplifier as a function of the variations of both the active device doping and the circuit layout. The statistical distribution of the output power significantly depends on the power backoff and exhibits a marked skew, which cannot be fully addressed by standard sensitivity or linearized approaches. The effect of correlated or uncorrelated active device or layout variations is also investigated in a combined stage.
{"title":"Physically-based statistical analysis of nonlinear circuits through X-parameters","authors":"S. Guerrieri, F. Bonani, G. Ghione","doi":"10.23919/EuMIC.2019.8909640","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909640","url":null,"abstract":"The active device X-parameters extracted from physics-based TCAD simulations are imported into the Keysight ADS environment following the techniques outlined in [1], leading to an efficient, yet physically sound, circuit-level nonlinear model, retaining a direct link with the device fabrication technology. In this work, the X parameter model is used to demonstrate that a fully statistical analysis of a nonlinear circuit as a function of technological spread of the active device can be efficiently carried out within ADS, with extremely reduced simulation time and excellent agreement with the original TCAD analysis. As a test case, we address the statistical analysis of a deep class AB amplifier as a function of the variations of both the active device doping and the circuit layout. The statistical distribution of the output power significantly depends on the power backoff and exhibits a marked skew, which cannot be fully addressed by standard sensitivity or linearized approaches. The effect of correlated or uncorrelated active device or layout variations is also investigated in a combined stage.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134539544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909457
C. Bredendiek, K. Aufinger, N. Pohl
This paper presents ultra-wideband fundamental VCOs in a automotive qualified production SiGe:C hetero bipolar technology with an fT of 240GHz and fmax of 380GHz. The architecture of the VCOs is a fully differential topology based on a merge of the classic Colpitts- and Clapp-topologies. The VCOs are designed for a continuous tuning range to cover one full millimeter-waveguide band. The goal of this particular work is to encompass the full E- and W-Band, respectively. The fabricated chips also integrate the high-frequency part of a divide-by-8 prescaler for stabilization in a PLL also covering the whole W-Band with up to 110 GHz efficiently. Both VCOs facilitate a peak output power of 7dBm in their respective band at the differential output. The phase noise at 1MHz offset is -99dBc/Hz for the E-Band and -93dBc/Hz for the W-Band VCO at center frequency. The continuous tuning range is 31 GHz (40.1%) in the E-Band and 35.4 GHz (38.6%) in the W-Band. The characteristics are only slightly degrading even at 100° C. Only 215mW of power is consumed by the chips from a single 3.3V supply.
{"title":"Full Waveguide E- and W-Band Fundamental VCOs in SiGe:C Technology for Next Generation FMCW Radars Sensors","authors":"C. Bredendiek, K. Aufinger, N. Pohl","doi":"10.23919/EuMIC.2019.8909457","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909457","url":null,"abstract":"This paper presents ultra-wideband fundamental VCOs in a automotive qualified production SiGe:C hetero bipolar technology with an fT of 240GHz and fmax of 380GHz. The architecture of the VCOs is a fully differential topology based on a merge of the classic Colpitts- and Clapp-topologies. The VCOs are designed for a continuous tuning range to cover one full millimeter-waveguide band. The goal of this particular work is to encompass the full E- and W-Band, respectively. The fabricated chips also integrate the high-frequency part of a divide-by-8 prescaler for stabilization in a PLL also covering the whole W-Band with up to 110 GHz efficiently. Both VCOs facilitate a peak output power of 7dBm in their respective band at the differential output. The phase noise at 1MHz offset is -99dBc/Hz for the E-Band and -93dBc/Hz for the W-Band VCO at center frequency. The continuous tuning range is 31 GHz (40.1%) in the E-Band and 35.4 GHz (38.6%) in the W-Band. The characteristics are only slightly degrading even at 100° C. Only 215mW of power is consumed by the chips from a single 3.3V supply.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133825921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-01DOI: 10.23919/EuMIC.2019.8909600
A. M. Angelotti, Gian Piero Gibiin, C. Florian, A. Santarelli
GaN HEMT dispersive phenomena due to charge trapping can be effectively characterized by means of pulsed IV measurements. In this work, we exploit the wideband feature of the setup obtaining pulsed S-parameters measurements within narrow pulse widths, in the order of a few hundred ns. Then, we report the single and double-pulsed S-parameters characterization of the 100-nm GaN-on-Si HEMT technology by OMMIC, showing the impact of traps on the small-signal parameters and providing significant data for compact model identification.
{"title":"Narrow-pulse-width double-pulsed S-parameters measurements of 100-nm GaN-on-Si HEMTs","authors":"A. M. Angelotti, Gian Piero Gibiin, C. Florian, A. Santarelli","doi":"10.23919/EuMIC.2019.8909600","DOIUrl":"https://doi.org/10.23919/EuMIC.2019.8909600","url":null,"abstract":"GaN HEMT dispersive phenomena due to charge trapping can be effectively characterized by means of pulsed IV measurements. In this work, we exploit the wideband feature of the setup obtaining pulsed S-parameters measurements within narrow pulse widths, in the order of a few hundred ns. Then, we report the single and double-pulsed S-parameters characterization of the 100-nm GaN-on-Si HEMT technology by OMMIC, showing the impact of traps on the small-signal parameters and providing significant data for compact model identification.","PeriodicalId":228725,"journal":{"name":"2019 14th European Microwave Integrated Circuits Conference (EuMIC)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127860382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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