Pub Date : 2012-11-01DOI: 10.1109/RFIT.2012.6401626
Liguo Sun, Yinchao Chen, K. Sun
In this paper, the system on chip (SOC) and system in package (SiP) are discussed as two main approaches for system integration. The system on package (SOP) is introduced with the discussion of the integrated passive device (IPD). IPD based on silicon with high resistance is investigated and the SOP using silicon-based IPD is analyzed. It is found that the silicon-based IPD is a good candidate for the system integration, especially in radio frequency (RF) applications.
{"title":"System integration using silicon-based integrated passive device technology","authors":"Liguo Sun, Yinchao Chen, K. Sun","doi":"10.1109/RFIT.2012.6401626","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401626","url":null,"abstract":"In this paper, the system on chip (SOC) and system in package (SiP) are discussed as two main approaches for system integration. The system on package (SOP) is introduced with the discussion of the integrated passive device (IPD). IPD based on silicon with high resistance is investigated and the SOP using silicon-based IPD is analyzed. It is found that the silicon-based IPD is a good candidate for the system integration, especially in radio frequency (RF) applications.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"210 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121216060","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401631
A. Bansal, M. Raja, J. Minkyu
An ultra low power voltage reference circuit generating 1.0V and consuming 60nW from power supply of 1.3V is fabricated in 0.13um CMOS 1P6M process. It can work from battery voltage of 1.3V to 3.6V. The proposed reference circuit uses BJTs and a MOSFET operating in subthreshold region to generate temperature stable reference voltage. The reference circuit proposed in this work generates 1.0V unlike the conventional bandgap circuit where it is 1.2V. Conventional bandgap circuits use baseemitter voltage (VBE) of BJT as CTAT signal while proposed reference circuit uses gate-source voltage (VGS) of a sub-threshold region biased MOSFET. The reference voltage is an estimate of threshold voltage extrapolated up to 0°K. Subthreshold MOSFET used in this circuit is a high voltage transistor having threshold voltage of 0.65V at room temperature, hence it generates 1.0V. Using a low voltage MOSFET having threshold voltage 0.35V, this circuit generates reference voltage of 0.5V.
{"title":"A 60nW voltage reference circuit generating 1.0V using BJTs and subthreshold MOSFET","authors":"A. Bansal, M. Raja, J. Minkyu","doi":"10.1109/RFIT.2012.6401631","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401631","url":null,"abstract":"An ultra low power voltage reference circuit generating 1.0V and consuming 60nW from power supply of 1.3V is fabricated in 0.13um CMOS 1P6M process. It can work from battery voltage of 1.3V to 3.6V. The proposed reference circuit uses BJTs and a MOSFET operating in subthreshold region to generate temperature stable reference voltage. The reference circuit proposed in this work generates 1.0V unlike the conventional bandgap circuit where it is 1.2V. Conventional bandgap circuits use baseemitter voltage (VBE) of BJT as CTAT signal while proposed reference circuit uses gate-source voltage (VGS) of a sub-threshold region biased MOSFET. The reference voltage is an estimate of threshold voltage extrapolated up to 0°K. Subthreshold MOSFET used in this circuit is a high voltage transistor having threshold voltage of 0.65V at room temperature, hence it generates 1.0V. Using a low voltage MOSFET having threshold voltage 0.35V, this circuit generates reference voltage of 0.5V.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"138 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121592809","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401615
M. K. Ali, A. Hamidian, R. Shu, A. Malignaggi, G. Boeck
This work presents the design of a Q-band static frequency divider with quadrature signal output suitable for 60 GHz application. The RF performance improvement and power consumption reduction is achieved by using inductive peaking, resistor splitting techniques as well as proper transistor sizing. The static frequency divider is realized in a 90 nm CMOS technology with a chip area of 0.60×0.75 mm2. The self-oscillation frequency is 20.5 GHz with 12 GHz locking range. -16 dBm output power with less than -1 dBm input sensitivity were measured. The static frequency divider core and the output buffers consume 6.9 mW and 1.2 mW respectively from a 1.2 V power supply.
{"title":"45 GHz low power static frequency divider in 90 nm CMOS","authors":"M. K. Ali, A. Hamidian, R. Shu, A. Malignaggi, G. Boeck","doi":"10.1109/RFIT.2012.6401615","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401615","url":null,"abstract":"This work presents the design of a Q-band static frequency divider with quadrature signal output suitable for 60 GHz application. The RF performance improvement and power consumption reduction is achieved by using inductive peaking, resistor splitting techniques as well as proper transistor sizing. The static frequency divider is realized in a 90 nm CMOS technology with a chip area of 0.60×0.75 mm2. The self-oscillation frequency is 20.5 GHz with 12 GHz locking range. -16 dBm output power with less than -1 dBm input sensitivity were measured. The static frequency divider core and the output buffers consume 6.9 mW and 1.2 mW respectively from a 1.2 V power supply.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122488007","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401646
G. Ng, S. Arulkumaran, S. Vicknesh, H. Wang, K. Ang, C. M. Kumar, K. Ranjan, G. Lo, S. Tripathy, C. Boon, W. M. Lim
This work presents our recent progress on addressing two major challenges to realizing GaN-Silicon integration namely epitaxial growth of GaN-on-Silicon and CMOS-compatible process. We have successfully demonstrated 0.3-μm gate-length GaN HEMTs on 8-inch Si(111) substrate with fT of 28GHz and fmax of of 64GHz. These device performances are comparable to our reported devices fabricated on 4-inch Si substrate. We have also developed a GaN HEMT process with CMOS-compatible non-gold metal scheme. Excellent ohmic contacts (Rc=0.24 Ω-mm) with smooth surface morphology have been achieved which are comparable to those using conventional III-V gold-based ohmic contacts. 0.15-μm gate-length GaN HEMTs fabricated with this process achieved fT and fmax of 51 GHz and 50GHz respectively. The 5nm-thick AlGaN barrier HEMT exhibited three terminal OFF-state breakdown voltage (BVgd) of 83 V. Our results demonstrate the feasibility of realizing CMOS-compatible high performance GaN HEMTs on 8-inch silicon substrates for future GaN-on-Si integration.
{"title":"GaN-on-Silicon integration technology","authors":"G. Ng, S. Arulkumaran, S. Vicknesh, H. Wang, K. Ang, C. M. Kumar, K. Ranjan, G. Lo, S. Tripathy, C. Boon, W. M. Lim","doi":"10.1109/RFIT.2012.6401646","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401646","url":null,"abstract":"This work presents our recent progress on addressing two major challenges to realizing GaN-Silicon integration namely epitaxial growth of GaN-on-Silicon and CMOS-compatible process. We have successfully demonstrated 0.3-μm gate-length GaN HEMTs on 8-inch Si(111) substrate with fT of 28GHz and fmax of of 64GHz. These device performances are comparable to our reported devices fabricated on 4-inch Si substrate. We have also developed a GaN HEMT process with CMOS-compatible non-gold metal scheme. Excellent ohmic contacts (Rc=0.24 Ω-mm) with smooth surface morphology have been achieved which are comparable to those using conventional III-V gold-based ohmic contacts. 0.15-μm gate-length GaN HEMTs fabricated with this process achieved fT and fmax of 51 GHz and 50GHz respectively. The 5nm-thick AlGaN barrier HEMT exhibited three terminal OFF-state breakdown voltage (BVgd) of 83 V. Our results demonstrate the feasibility of realizing CMOS-compatible high performance GaN HEMTs on 8-inch silicon substrates for future GaN-on-Si integration.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122672045","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401639
Y. Zhang, Tu Zhihong
This paper reports the measurement of the input impedance of a differential microstrip antenna by the balun method for the first time. The balun method is described and obtained experimental results are discussed.
本文首次用平衡法测量了差分微带天线的输入阻抗。介绍了平衡法，并对得到的实验结果进行了讨论。
{"title":"Measurement of input impedance of differential microstrip antenna by balun method","authors":"Y. Zhang, Tu Zhihong","doi":"10.1109/RFIT.2012.6401639","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401639","url":null,"abstract":"This paper reports the measurement of the input impedance of a differential microstrip antenna by the balun method for the first time. The balun method is described and obtained experimental results are discussed.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133455872","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401638
S. Amakawa, K. Takano, K. Katayama, M. Motoyoshi, T. Yoshida, M. Fujishima
Performance of thru-only cascade de-embedding methods and their variants that use a Π- or a T-equivalent to represent and bisect a symmetric THRU is assessed. The results from the Π- and T-based methods are reasonable at low frequencies. However they are shown to deviate noticeably from the correct results as the frequency gets high or, equivalently, when the length of the THRU approaches an effective wavelength λ. A better alternative at high frequencies is TSD (thru-short-delay), which, when THRU is symmetric, requires only THRU and LINE. TSD gives correct results except in the periodically appearing `dead zones', provided that the characteristic impedance, Zχ, of the transmission line (TL) in the LINE is known. A Π-based method could be used to extract Zχ at low frequencies, from which Zχ can be extrapolated to higher frequencies.
{"title":"On the choice of cascade de-embedding methods for on-wafer S-parameter measurement","authors":"S. Amakawa, K. Takano, K. Katayama, M. Motoyoshi, T. Yoshida, M. Fujishima","doi":"10.1109/RFIT.2012.6401638","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401638","url":null,"abstract":"Performance of thru-only cascade de-embedding methods and their variants that use a Π- or a T-equivalent to represent and bisect a symmetric THRU is assessed. The results from the Π- and T-based methods are reasonable at low frequencies. However they are shown to deviate noticeably from the correct results as the frequency gets high or, equivalently, when the length of the THRU approaches an effective wavelength λ. A better alternative at high frequencies is TSD (thru-short-delay), which, when THRU is symmetric, requires only THRU and LINE. TSD gives correct results except in the periodically appearing `dead zones', provided that the characteristic impedance, Zχ, of the transmission line (TL) in the LINE is known. A Π-based method could be used to extract Zχ at low frequencies, from which Zχ can be extrapolated to higher frequencies.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132481186","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401630
J. Pathrose, Xiaohui Gong, L. Zou, J. Koh, K. Chai, M. Je, Y. Xu
This paper describes a bandgap reference with temperature range up to 300°C. Fabricated in a PDSOI CMOS technology, the bandgap reference achieves a box model temperature coefficient of 138ppm from 25 to 300°C, and line regulation less than 1.5mv/V. The minimum operating voltage is 2V and consumes merely 285μW at room temperature over several samples.
{"title":"High temperature bandgap reference in PDSOI CMOS with operating temperature up to 300°C","authors":"J. Pathrose, Xiaohui Gong, L. Zou, J. Koh, K. Chai, M. Je, Y. Xu","doi":"10.1109/RFIT.2012.6401630","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401630","url":null,"abstract":"This paper describes a bandgap reference with temperature range up to 300°C. Fabricated in a PDSOI CMOS technology, the bandgap reference achieves a box model temperature coefficient of 138ppm from 25 to 300°C, and line regulation less than 1.5mv/V. The minimum operating voltage is 2V and consumes merely 285μW at room temperature over several samples.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116694843","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401627
Dai Zhou, Pang Xueman, Cheng Kai, W. Ziliang
Alumina ceramic with enhanced dielectric property was reported in this paper, which indicates its microwave application. Commercial A1203 powder and sintering aids including MgO were utilized to fabricate alumina ceramic substrate. Liquid deposit was introduced to wrap the surface of A1203 powder with MgO additives uniformly. The prepared composite powder was shaped by tape casting and sintered by two-step sintering to ensure density and suitable microstructure. It is shown that MgO addition restrains gain growing and decreases porosity in scanning electron micrograph. MgA1204 spinel, formed by MgO was detected by XRD. The dielectric loss of the alumina ceramic substrate is 6.84 × 10-4.
{"title":"Enhanced dielectric properties of alumina ceramic substrate for microwave application","authors":"Dai Zhou, Pang Xueman, Cheng Kai, W. Ziliang","doi":"10.1109/RFIT.2012.6401627","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401627","url":null,"abstract":"Alumina ceramic with enhanced dielectric property was reported in this paper, which indicates its microwave application. Commercial A1203 powder and sintering aids including MgO were utilized to fabricate alumina ceramic substrate. Liquid deposit was introduced to wrap the surface of A1203 powder with MgO additives uniformly. The prepared composite powder was shaped by tape casting and sintered by two-step sintering to ensure density and suitable microstructure. It is shown that MgO addition restrains gain growing and decreases porosity in scanning electron micrograph. MgA1204 spinel, formed by MgO was detected by XRD. The dielectric loss of the alumina ceramic substrate is 6.84 × 10-4.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124427492","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401635
Sheng Sun, Danting Xu, Q. S. Liu, F. Lin
In this paper, a wireless power transfer (WPT) system based on two spiral magnetic-coupled resonators is studied and realized on the printed circuit board (PCB). For the mid-range energy transfer, the microwave filter design theory can be employed to explain the basic principle of magnetic induction in WPT system. Based on the filtering transfer function, the power transfer efficiency is defined by Scattering matrix. In particular, the transfer distance between two resonators can be easily optimized according to the filtering specifications. As an example, Chebyshev function is selected to synthesize the two-pole transmission peaks, which is so-called frequency splitting in power community. Then, the transfer distances can be determined from the required external Q-factor and coupling coefficient. Finally, a PCB-based WPT system fed by two loops is designed, implemented, and verified experimentally.
{"title":"From filter to mid-range wireless power transfer system","authors":"Sheng Sun, Danting Xu, Q. S. Liu, F. Lin","doi":"10.1109/RFIT.2012.6401635","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401635","url":null,"abstract":"In this paper, a wireless power transfer (WPT) system based on two spiral magnetic-coupled resonators is studied and realized on the printed circuit board (PCB). For the mid-range energy transfer, the microwave filter design theory can be employed to explain the basic principle of magnetic induction in WPT system. Based on the filtering transfer function, the power transfer efficiency is defined by Scattering matrix. In particular, the transfer distance between two resonators can be easily optimized according to the filtering specifications. As an example, Chebyshev function is selected to synthesize the two-pole transmission peaks, which is so-called frequency splitting in power community. Then, the transfer distances can be determined from the required external Q-factor and coupling coefficient. Finally, a PCB-based WPT system fed by two loops is designed, implemented, and verified experimentally.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124224391","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 : 2012-11-01DOI: 10.1109/RFIT.2012.6401603
Xue Zhang, Shengyang Tian, Hongxi Xue
In a traditional Inverter Circuit, using parallel power MOSFETs is a common practice to improve the performance of the circuit. However, in a wireless power transfer system using magnetic resonance coupling technique, the method of parallel MOSFET would cause a lot of problems: the speed of the MOSFET converter would decrease; the switching loss would increase. The worst situation is that the switch would not be able to meet the operating frequency of the Magnetic Resonance system. As a result, we introduce the Multi-switch Method to solve the problem above. From simulation, this method could reduce the loss of an individual switch. In this paper, we design a multi-switch circuit, and compare it with the traditional inverter circuit in a magnetic resonance system. Then we analyzed the individual switch loss in these two circuits by a comparative experiment to verify the effectiveness of this new circuit. The result suggests that, this multi-switch circuit improve the individual performance of the switch, and reduce the voltage oscillating waveform of the switch significantly.
{"title":"Application of multi-switch in wireless power system","authors":"Xue Zhang, Shengyang Tian, Hongxi Xue","doi":"10.1109/RFIT.2012.6401603","DOIUrl":"https://doi.org/10.1109/RFIT.2012.6401603","url":null,"abstract":"In a traditional Inverter Circuit, using parallel power MOSFETs is a common practice to improve the performance of the circuit. However, in a wireless power transfer system using magnetic resonance coupling technique, the method of parallel MOSFET would cause a lot of problems: the speed of the MOSFET converter would decrease; the switching loss would increase. The worst situation is that the switch would not be able to meet the operating frequency of the Magnetic Resonance system. As a result, we introduce the Multi-switch Method to solve the problem above. From simulation, this method could reduce the loss of an individual switch. In this paper, we design a multi-switch circuit, and compare it with the traditional inverter circuit in a magnetic resonance system. Then we analyzed the individual switch loss in these two circuits by a comparative experiment to verify the effectiveness of this new circuit. The result suggests that, this multi-switch circuit improve the individual performance of the switch, and reduce the voltage oscillating waveform of the switch significantly.","PeriodicalId":187550,"journal":{"name":"2012 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131937456","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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