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Load-pull measurement analysis of AlGaN/GaN HEMT taking into account number of gate fingers

Pongthavornkamol Tiwat, Guoguo Liu, Tingting Yuan, Yingkui Zheng and Xinyu Liu

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 Corresponding author: Pongthavornkamol Tiwat, Email: lintiyuan@ime.ac.cn

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Abstract: This paper investigates load-pull measurement of AlGaN/GaN high electron mobility transistors (HEMTs) at different numbers of gate fingers. Scalable small-signal models are extracted to analyze the relationship between each model's parameters and the number of device's gate fingers. The simulated S-parameters from the small-signal models are compared with the reflection coefficients measured from the load-pull measurement system at X-band frequencies of 8.8 and 10.4 GHz. The dependency between the number of device's gate fingers and load-pull characterization is presented.

Key words: AlGaN/GaN HEMTgate fingerssmall-signal modelload-pull measurement



[1]
Resca D, Raffo A, Falco S D, et al. X-band GaN power amplifier for future generation SAR systems. IEEE Microw Wireless Compon Lett, 2014, 24(4):266
[2]
Ge Qin, Liu Xinyu, Zheng Yingkui, et al. A flat gain GaN MMIC power amplifier for X band application. Journal of Semiconductors, 2014, 35(12):125004
[3]
Cao M Y, Zhang K, Chen Y H, et al. High-efficiency S-band harmonic tuning GaN amplifier. Chin Phys B, 2013, 23(3):037305
[4]
Muller J E, Laudien M and Muller H. On-wafer load-pull characterization of self-aligned GaAs power MESFETs. European Microwave Conference, 1991:1379
[5]
Abe H, Aono Y. 11-GHz GaAs power MESFET load-pull measurements utilizing a new method of determining tuner Y parameters. IEEE Trans Microw Theory Tech, 1979, 27(5):394
[6]
Bengtsson O, Chevtchenko S A, Doerner R, et al. Load-pull investigation of GaN HEMT for supply modulated applications. German Microwave Conference, 2011:1
[7]
Gao S J, Park C W. Large signal characterization of GaN HEMT transistors by multi-harmonic source & load pull tuner system. Microwave Measurement Symposium, 2012:1
[8]
Gao J. RF and microwave modeling and measurement techniques for field effect transistors. Raleigh:SciTech Publishing, 2009:204
[9]
Dambrine G, Cappy A, Heliodore F, et al. A new method for determining the FET small-signal equivalent circuit. IEEE Trans Microw Theory Tech, 1988, 36(7):1151
[10]
Jarndal A, Kompa G. An accurate small-signal model for AlGaN/GaN HEMT suitable for scalable large-signal model construction. IEEE Microw Wireless Compon Lett, 2006, 16(6):333
[11]
Gonzalez G. Microwave transistor amplifier analysis and design. Upper Saddle River:Prentice-Hall, 1997:212
[12]
Pongthavornkamol T, Pang L, Yuan T T, et al. Improved power simulation of AlGaN/GaN HEMT at class-AB operation via an RF drain-source current correction. Chin Phys B, 2014, 23(12):127304
Fig. 1.  Top view of AlGaN/GaN HEMTs with different number of fingers. (a) 4 × 100 μm. (b) 6 × 100 μm. (c) 8 × 100 μm.

Fig. 2.  Small-signal equivalent circuit model for AlGaN/GaN HEMT.

Fig. 3.  S-parameters simulation (solid line) and measurement (circle) of 6 × 100 μm gate width device with 100 MHz - 40 GHz frequency range at Vgs=-3.5 V,Vds=30 V.

Fig. 4.  Conjugate matching between output return loss of device and load reflection coefficient.

Fig. 5.  Output shunt capacitances at bias condition of Vgs= -3.5 V and Vds= 30 V extracted from (a) small-signal modeling and (b) load-pull measurement.

Fig. 6.  Smith chart of measured reflection coefficient at load side (ΓL) from load-pull system versus conjugate output return loss (S22*) of typical and optimized small-signal models at bias condition of (Vgs)= -3.5 V,(Vds)= 30 V.

Fig. 7.  (Color online) Power gain measurement of GaN HEMT by load-pull system with class-AB bias (Vgs = -3.5 V,Vds = 30 V) at X-band frequencies (a) 8.8 GHz,(b) 10.4 GHz.

Table 1.   Small-signal model parameters at bias condition of Vgs = -3.5 V and Vds=30 V.

ParameterNumber of gate finger
468
Rd (Ω)10.177.26.49
Ld (pH)32.458.9969.53
Cds (fF)201.79219.44269.62
Rds (Ω)41.447.954.8
Rs (Ω)10.335.74.02
Ls (pH)1.011.261.2
Rgd (Ω)1.022.161
Cgd (fF)9.9268.44134.07
Rg (Ω)1.562.091.66
Lg (pH)54.9767.0364.41
Cgs (fF)2509.581347.731389.68
Cpg (fF)45.4333.4828.2
Cpd (fF)17.8618.9729.35
Cpgd (fF)5.015.555.61
Ri (Ω)1.00721.0011.0023
gm (mS)695.5346.8330.8
τ(μs)0.20.20.2
DownLoad: CSV

Table 2.   Load impedance of,load-pull measurement and conjugate output impedance of small-signal model at bias condition of Vgs=-3.5 V,Vds = 30 V

Gate width(μm)Frequency(GHz)Impedance (Ω)
ZL,LPZout;SSM*
4 × 1008.8 38.94C53.81j 41.7C36.08j
6 × 1008.8 28.31C38.22j 30.16C17.19j
8 × 1008.8 13.09C30.23j 24.63C10.43j
4 × 10010.4 41.34C49.68j 39.37C32.78j
6 × 10010.4 23.01C41.7j 28.95C15.54j
8 × 10010.4 13.53C25j 23.65C9.26j
DownLoad: CSV

Table 3.   Small-signal model parameters of typical condition (Pin = 0 dBm) and load-pull condition with 1-dB compression input power (Pin =P1dB) at bias condition of Vgs = -3.5 V,Vds= 30 V.

Gate width (μm) Parameters Typical Load-pull
4 × 100 Cds (fF)154170
Cgd (fF)9.97
Rds(Ω)41.460
gm (mS)695.5730
Cgs (fF)25102600
6 × 100 Cds (fF)219.4240
Cgd (fF)68.427
Rds (Ω)47.9120
gm (mS)347550
Cgs (fF)1347.72000
8 × 100 Cds (fF)269.6450
Cgd (fF)134.130
Rds (Ω)54.8200
gm (mS)331500
Cgs (fF)1389.72300
DownLoad: CSV
[1]
Resca D, Raffo A, Falco S D, et al. X-band GaN power amplifier for future generation SAR systems. IEEE Microw Wireless Compon Lett, 2014, 24(4):266
[2]
Ge Qin, Liu Xinyu, Zheng Yingkui, et al. A flat gain GaN MMIC power amplifier for X band application. Journal of Semiconductors, 2014, 35(12):125004
[3]
Cao M Y, Zhang K, Chen Y H, et al. High-efficiency S-band harmonic tuning GaN amplifier. Chin Phys B, 2013, 23(3):037305
[4]
Muller J E, Laudien M and Muller H. On-wafer load-pull characterization of self-aligned GaAs power MESFETs. European Microwave Conference, 1991:1379
[5]
Abe H, Aono Y. 11-GHz GaAs power MESFET load-pull measurements utilizing a new method of determining tuner Y parameters. IEEE Trans Microw Theory Tech, 1979, 27(5):394
[6]
Bengtsson O, Chevtchenko S A, Doerner R, et al. Load-pull investigation of GaN HEMT for supply modulated applications. German Microwave Conference, 2011:1
[7]
Gao S J, Park C W. Large signal characterization of GaN HEMT transistors by multi-harmonic source & load pull tuner system. Microwave Measurement Symposium, 2012:1
[8]
Gao J. RF and microwave modeling and measurement techniques for field effect transistors. Raleigh:SciTech Publishing, 2009:204
[9]
Dambrine G, Cappy A, Heliodore F, et al. A new method for determining the FET small-signal equivalent circuit. IEEE Trans Microw Theory Tech, 1988, 36(7):1151
[10]
Jarndal A, Kompa G. An accurate small-signal model for AlGaN/GaN HEMT suitable for scalable large-signal model construction. IEEE Microw Wireless Compon Lett, 2006, 16(6):333
[11]
Gonzalez G. Microwave transistor amplifier analysis and design. Upper Saddle River:Prentice-Hall, 1997:212
[12]
Pongthavornkamol T, Pang L, Yuan T T, et al. Improved power simulation of AlGaN/GaN HEMT at class-AB operation via an RF drain-source current correction. Chin Phys B, 2014, 23(12):127304
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    Received: 16 September 2015 Revised: 21 December 2015 Online: Published: 01 June 2016

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      Pongthavornkamol Tiwat, Guoguo Liu, Tingting Yuan, Yingkui Zheng, Xinyu Liu. Load-pull measurement analysis of AlGaN/GaN HEMT taking into account number of gate fingers[J]. Journal of Semiconductors, 2016, 37(6): 064008. doi: 10.1088/1674-4926/37/6/064008 P Tiwat, G G Liu, T T Yuan, Y K Zheng, X Y Liu. Load-pull measurement analysis of AlGaN/GaN HEMT taking into account number of gate fingers[J]. J. Semicond., 2016, 37(6): 064008. doi: 10.1088/1674-4926/37/6/064008.Export: BibTex EndNote
      Citation:
      Pongthavornkamol Tiwat, Guoguo Liu, Tingting Yuan, Yingkui Zheng, Xinyu Liu. Load-pull measurement analysis of AlGaN/GaN HEMT taking into account number of gate fingers[J]. Journal of Semiconductors, 2016, 37(6): 064008. doi: 10.1088/1674-4926/37/6/064008

      P Tiwat, G G Liu, T T Yuan, Y K Zheng, X Y Liu. Load-pull measurement analysis of AlGaN/GaN HEMT taking into account number of gate fingers[J]. J. Semicond., 2016, 37(6): 064008. doi: 10.1088/1674-4926/37/6/064008.
      Export: BibTex EndNote

      Load-pull measurement analysis of AlGaN/GaN HEMT taking into account number of gate fingers

      doi: 10.1088/1674-4926/37/6/064008
      Funds:

      the National Natural Science Foundation of China (No. 61204086)

      the National Natural Science Foundation of China No. 61204086

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      • Corresponding author: Email: lintiyuan@ime.ac.cn
      • Received Date: 2015-09-16
      • Revised Date: 2015-12-21
      • Published Date: 2016-06-01

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