THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE Dec.; 25(12),

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1 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE Dec.; 25(12), ISSN (Print)ISSN X (Online) UHF RFID Modelling Method for Removing Measurement Uncertainty in Chip Impedance Characterization of UHF RFID Tag IC 양진모 Jeenmo Yang 요약 UHF RFID..,,.,. Abstract Input impedance of UHF RFID tag chip is needed to design a tag. In determining the chip impedance, direct measurement method is adopted commonly. In this paper, problems generated from fixtures that interface between tag chip and coaxial-oriented measurement instrument are investigated and the result of the problems is shown, when the direct measurement method is applied. As an alternative to the method, a modeling method is proposed and its validity and accuracy are shown. Key words: RFID Tag, Chip Impedance, Direct Measurement, Modelling Method. 서론 UHF RFID, (tag) (reader) [1]. [1],[2]., [3]. (direct measurement method) [1],[4][6] (modeling method) [7][9], (model optimization method) [9],[10]. 1, (fixture) (School of Electronic and Electrical Engineering, Daegu University) Manuscript received October 17, 2014 ; Revised November 19, 2014 ; Accepted November 25, (ID No ) Corresponding Author: Jeenmo Yang ( jmyang@daegu.ac.kr) 1228 c Copyright The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved.

2 UHF RFID. (non-coaxial type) DUT (Device Under Test) (coaxial type) VNA(Vector Network Analyzer) (probe) (interface). VNA (systematic error) [11] (reference plane) 1(a) DUT., DUT VNA DUT, DUT VNA..,., DUT DUT., (non-uniform) (uncertainty) [12]. (a) (a) Direct measurement method (b) (b) Modelling method 그림 1. Fig. 1. Measurement configuration. [1],[5].. [4][6].,. UHF RFID --(Short-Open- Load) [8],[12],,.. 직접측정방법의불확실성 (=Z c) 2(a) VNA ( =Z o ), VNA (reflection coefficient) S 11 S 11 Z = Z c c - Z0 + Z (1) 0 Z c, (P c ) c NA 2 ( 1 ) 11 P = P - S [1],[4]. P NA VNA. VNA, (Z 0 )., Z 0., Z 0. 2(b). ( =Z o ) Probe +, ( (2) 1229

3 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 25, no. 12, Dec (a) (a) Measurement without the fixture (b) (b) Measurement with the fixture 그림 2. Fig. 2. Measurement set-up for the direct measurement method. =Z f ) Fixture. Z o Z f,. 2(b) VNA (V + ). V 1 V + Fixture, V 2 V 3. V 4 V 3 Fixture, Fixture Fixture (V 2 V 3 ). VNA (S 11 ). 2(b) V 2 V 3., V 4 Fixture, (V 4 ) (V 2 V 3 ) (), (). Fixture, (Z o, Z f, Z c ). V 4 V 2 V 3 VNA S- (S 11m ). VNA. SOL(Short-Open-Load) [8],[11],[12] TRL(Through-Reflect-Line) [8],[11], S-(S 11m ) (3) S-(S 11a ) [8],[11],[12]. S 11a ( S11 m - ED ) = E + E ( S - E ) (3) rt s 11m D E rt, E s, E D 2(b) // (Short/Open/Load) S 11a 1/+1/0 (systematic error term),., 0,, Z o V 4 (3) (systematic error correction) VNA S- [11],[12]., V 4 S 11a. jx, 3 o., (uncertainty region). aa bb (1) 1. aa 1230

4 UHF RFID 0 1 b o a a b Uncertainty region 그림 3. S- Fig. 3. Variation of S-parameter due to measurement uncertainty. 표 1. S- Table 1. Variation in evaluated impedance due to S-parameter uncertainty.., bb (+R x R x ). (X),, (R x)., [13],[14]. (R+jX), (R), (X)., (). 4. 그림 4. Fig. 4. Variation of evaluated tag chip impedance when using the direct measurement method.. 모델링방법 DUT DUT [7][9].. 1(b), VNA,. (VNA)..,,. [1],[4]~[7],[10]. 5 DUT,,. (lumped-parameter) () 10 % 1231

5 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 25, no. 12, Dec ,.. 실험 그림 5. 1(b) Fig. 5. Electrical equivalent circuit for the measurement system of Fig. 1(b).., (L s ). (R p ) (loss tangent), (C p ). 2. R NA VNA ( 50 Ω), P NA VNA. Y a DUT open S- Y-, Y b short Y-, Y c Y-.. S-. 표 2. Table 2. Model parameter evaluation equation for the electrical equivalent circuit.,. 6, SMA (Amphenol P/N ). SMA 2, DUT. TSSOP(Thin Shrink Small Out-line Package) [4][6],[15],. 6(a) Short Open SMA, Load Anaren 50 Ω(tolerance < GHz) RF. 6(b) Fully open SMA, (port extension) [11]. Chip (a) (b) 그림 6.. (a), (b) Fig. 6. Fixtures for (a) direct measurement method, (b) modeling method. 1232

6 UHF RFID.,. AVX UHF, (1±0.02 pf 2±0.05 pf),. Agilent N5230A VNA 6(a) SOL(Short-Open-Load) --(In-Fixture Calibration) [8]. S- VNA 5 dbm MHz Chip S-.,. 3 b., 3, 5.5 %, () ().,. 1 pf( 이론값 ) 1 pf( 직접측정방법값 ) 2 pf( 이론값 ) 2 pf( 직접측정방법값 ) 그림 MHz S- Fig. 7. S-parameter value of capacitor chip fixtures meaured at 915 MHz frequency. 표 3. Table 3. Impedance evaluation results for the capacitor chip fixtures using the direct measurement MHz 1 pf 9.1j pf 4.6j82.8. Load 6(b) Fully open.,. (1±0.02 pf 2±0.05 pf ). S-. SOL, 6(b) Fully open. 6(b) S- Y-, 2. 8., (1±2 % pf 2±2.5 % pf), 3 %, 0.1 W.., Monza 4 Dura(IPJ-P5003) [16],. S-, VNA 1233

7 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 25, no. 12, Dec 그림 8. Fig. 8. Evaluation result for the capacitor chip fixtures using the proposed modeling method. 표 4. Monza 4 Dura Table 4. Comparison of Monza 4 Dura tag chip impedance obtained from the two evaluation method. MHz 1.8j j j143 (read threshold power). 4., ()., 5.5 %.,,.. 결론 UHF RFID..,, SMA,...,. UHF RFID,. References [1] P. V. Nikitin, K. V. Seshagiri Rao, R. Martinez, and S. F. Lam, "Sensitivity and impedance measurements of UHF RFID chips", IEEE Trans. Microw. Theory Tech., vol. 57, no. 5, pp , May [2] M. Dhaouadi, M. Mabrouk, T. P. Vuong, D. Hamzaoui, and A. Ghazel, "Chip impedance matching for UHF-band RFID tag", in Proc. 7 th EuCAP, pp , Apr [3] J. Choo, J. Ryoo, "Analysis of flip chip bonding for performance stability of UHF RFID tags", IEEE Trans. Compon, Packag. Manuf. Technol., vol. PP, Issue. 99, pp. 1-8, Aug [4] R. Kronberger, A. Geissler, and B. Friedmann, "New methods to determine the impedance of UHF RFID chips", in Proc. IEEE Int. Conf. RFID, pp , Apr [5] G. Andia Vera, Y. Duroc, and S. Tedjini, "RFID test platform: nonlinear characterization", IEEE Trans. Instrum. Meas., vol. 63, no. 9, pp , Sep [6] H. Ge, Y. Yao, J. Yu, and X. Chen, "Binary RFID chip impedance measurement for UHF tag antenna design", in Proc. IEEE APSURSI, pp , Jul [7] J. Yang, J. Yeo, "Chip impedance evaluation method for 1234

8 UHF RFID UHF RFID transponder ICs over absorbed input power", ETRI Journal, vol. 32, no. 6, pp , [8] "In-fixture measurements using vector network analyzers", Agilent application note [9] A. Issaoun, Y. Z. Xiong, J. Shi, J. Brinkhoff, and F. Lin, "On the deembedding issue of CMOS multigigahertz measurements", IEEE Trans. Microw. Theory Tech., vol. 55, no. 9, pp , [10] F. M. Janeiro, J. R. Costa, C. A. Fernandes, and P. M. Ramos, "RFID chip characterization through S-parameter measurements and gene expression programming", in Proc. I2MTC, pp , May [11] "Agilent network analyzer basics", Agilent Technologies, [12] "Applying error correction to network analyzer mea- 태그 칩의 임피던스 산출 불확실성 제거를 위한 모델링 방법 surements", Agilent application note [13] J. Lee, N. D. Phan, D. H. Vo, and V. Duong, "A fully integrated EPC gen-2 UHF-band passive tag IC using an efficient power management technique", IEEE Trans. Ind. Elecron., vol. 61, no. 6, pp , Jun [14] C. Yao, W. Hsia, "A 21.2-dBm dual-channel UHF passive CMOS RFID tag design", IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 61, no. 4, pp , Apr [15] C. Huang, X. Gu, et al., "An adaptive Q factor tuning and input impedance matching method for ultra-low power front end of UHF RFID tag", in Proc. 10th ASICON, pp. 1-4, Oct [16] Monza 4 Tag Chip Datasheet. [Online]. Available: 양진 모 년 월 경북대학교 전자공학과 (공학 사 년 월 버지니아공과대학교 전기공 학과 공학석사) 년 월 조지아공과대학 전기및컴퓨 터공학과 (공학박사) 1994년 3월 현재: 대구대학교 전자전기 공학부 교수 [주 관심분야] RF 소자 모델링, RFID 태그 설계 : ) : ( : 1235