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EE5342 – Semiconductor Device Modeling and Characterization Lecture 19 - Spring 2005

EE5342 – Semiconductor Device Modeling and Characterization Lecture 19 - Spring 2005. Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/. Project 1 I-V. Project 1 C-V. Project 1 Z-parameters. Project 1 Circuit and Parameters. Values chosen for SPICE parameters.

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EE5342 – Semiconductor Device Modeling and Characterization Lecture 19 - Spring 2005

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  1. EE5342 – Semiconductor Device Modeling and CharacterizationLecture 19 - Spring 2005 Professor Ronald L. Carter ronc@uta.edu http://www.uta.edu/ronc/

  2. Project 1 I-V

  3. Project 1 C-V

  4. Project 1 Z-parameters

  5. Project 1 Circuit and Parameters

  6. Values chosen for SPICE parameters

  7. The limiting values of Re{Z}, with corner frequency, effective total capacitance and transit time (both raw and adjusted to include rd,inj only).

  8. Charge componentsin the BJT From Getreau, Modeling the Bipolar Transistor, Tektronix, Inc.

  9. Gummel-Poon Staticnpn Circuit Model Intrinsic Transistor C RC IBR B RBB ILC ICC -IEC = {IS/QB}* {exp(vBE/NFVt)-exp(vBC/NRVt)} IBF B’ ILE RE E

  10. Gummel-PoonModel General Form QXXXXXXX NC NB NE <NS> MNAME <AREA> <OFF> <IC=VBE, VCE> <TEMP=T> Netlist Examples Q5 11 26 4 Q2N3904 IC=0.6, 5.0 Q3 5 2 6 9 QNPN .67 NC, NB and NE are the collector, base and emitter nodes NS is the optional substrate node; if unspecified, the ground is used. MNAME is the model name, AREA is the area factor, and TEMP is the temperature at which this device operates, and overrides the specification in the Analog Options dialog.

  11. Gummel-PoonStatic Model Gummel Poon Model Parameters (NPN/PNP) Adaptation of the integral charge control model of Gummel and Poon. Extends the original model to include effects at high bias levels. Simplifies to Ebers-Moll model when certain parameters not specified. Defined by parameters IS, BF, NF, ISE, IKF, NE determine forward characteristics IS, BR, NR, ISC, IKR, NC determine reverse characteristics VAF and VAR determine output conductance for for and rev RB(depends on iB), RC, and RE are also included

  12. Gummel-Poon Static Par. NAME PARAMETER UNIT DEFAULT IS transport saturation current A 1.0e-16 BF ideal maximum forward beta - 100 NF forward current emission coef. - 1.0 VAF forward Early voltage V infinite ISE B-E leakage saturation current A 0 NE B-E leakage emission coefficient - 1.5 BR ideal maximum reverse beta - 1 NR reverse current emission coeff. - 1 VAR reverse Early voltage V infinite ISC B-C leakage saturation current A 0 NC B-C leakage emission coefficient - 2 EG energy gap (IS dep on T) eV 1.11 XTI temperature exponent for IS - 3

  13. Gummel-Poon StaticModel Parameters NAME PARAMETER UNIT DEFAULT IKF corner for forward beta A infinite high current roll-off IKR corner for reverse beta A infinite high current roll-off RB zero bias base resistance W 0 IRB current where base resistance A infinite falls halfway to its min value RBM minimum base resistance W RB at high currents RE emitter resistance W 0 RC collector resistance W 0 TNOM parameter - meas. temperature °C 27

  14. IBF = ISexpf(vBE/NFVt)/BF ILE = ISEexpf(vBE/NEVt) IBR = ISexpf(vBC/NRVt)/BR ILC = ISCexpf(vBC/NCVt) QB = (1 + vBC/VAF + vBE/VAR ) {½ + [¼ + (BFIBF/IKF + BRIBR/IKR)]1/2} Gummel Poon npnModel Equations

  15. IBF = IS expf(vBE/NFVt)/BF ILE = ISE expf(vBE/NEVt) IBR = IS expf(vBC/NRVt)/BR ILC = ISC expf(vBC/NCVt) ICC -IEC = IS(exp(vBE/NFVt - exp(vBC/NRVt)/QB QB= {½+[¼+(BFIBF/IKF + BRIBR/IKR)]1/2} (1 - vBC/VAF - vBE/VAR )-1 Gummel Poon npnModel Equations

  16. Gummel PoonBase Resistance If IRB = 0, RBB = RBM+(RB-RBM)/QB If IRB > 0 RB = RBM + 3(RB-RBM)(tan(z)-z)/(ztan2(z)) [1+144iB/(p2IRB)]1/2-1 z = (24/p2)(iB/IRB)1/2 Regarding (i) RBB and (x) RTh on slide 23, RBB = Rbmin + Rbmax/(1 + iB/IRB)aRB

  17. Gummel PoonBase Resistance If IRB = 0, RBB = RBM+(RB-RBM)/QB If IRB > 0 RB = RBM + 3(RB-RBM)(tan(z)-z)/(ztan2(z)) [1+144iB/(p2IRB)]1/2-1 z = (24/p2)(iB/IRB)1/2 Regarding (i) RBB and (x) RTh on previous slide, RBB = Rbmin + Rbmax/(1 + iB/IRB)aRB

  18. The base current must flow lateral to the wafer surface Assume E & C cur-rents perpendicular Each region of the base adds a term of lateral res. vBE diminishes as current flows coll. base & emitter contact regions reg 1 reg 2 reg 3 reg 4 emitter base collector Distributed resis-tance in a planar BJT

  19. Distributed device is repr. by Q1, Q2, … Qn Area of Q is same as the total area of the distributed device. Both devices have the same vCE = VCC Both sources have same current iB1 = iB. The effective value of the 2-dim. base resistance is Rbb’(iB) = DV/iB = RBBTh  DV  = Simulation of 2-dim. current flow

  20. Analytical solutionfor distributed Rbb • Analytical solution and SPICE simulation both fit RBB = Rbmin + Rbmax/(1 + iB/IRB)aRB

  21. Distributed baseresistance function Normalized base resis-tance vs. current. (i) RBB/RBmax, (ii) RBBSPICE/RBmax, after fitting RBB and RBBSPICE to RBBTh (x) RBBTh/RBmax. FromAn Accurate Mathematical Model for the Intrinsic Base Resistance of Bipolar Transistors, by Ciubotaru and Carter, Sol.-St.Electr. 41, pp. 655-658, 1997. RBBTh = RBM + DR/(1+iB/IRB)aRB (DR = RB - RBM )

  22. References * Modeling the Bipolar Transistor, by Ian Getreau, Tektronix, Inc., (out of print).

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