Status of HICUM/L2 Model

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Isabella Parsons
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1 Status of HICUM/L2 Model A. Pawlak 1), M. Schröter 1),2), A. Mukherjee 1) 1) CEDIC, University of Technology Dresden, Germany 2) Dept. of Electrical and Computer Engin., University of Calif. at San Diego, USA Bipolar Arbeitskreis 2014, Crolles AP, MS 1

2 Overview Overview Verisons of HICUM/L2 several changes in HICUM/L2 with version 2.30 version 2.31, 2.32 and 2.33 with minor changes Summary of changes/additions since HICUM/L2 version 2.30 simpification of lateral NQS modeling new model for correlated noise more flexible R th (T) formulation type flag for npn-transistors calculation of operating point values, added two new values named noise sources physical constants defined in model code bug-fixes / code corrections => details in VA-file header AP, MS 2

3 Overview Lateral NQS effect modeling Goal: improve computational efficiency by simplification AC analysis by using C RBi C RBi = f CRBi ( C jei + C jci + C dei + C dci ) Previous calculation of diffusion capacitances B* R Bi B V RBi C dei dq dei dq = and C jci dci = dv BE V BC dv BC V BE => were using ddx-operator Simplification avoiding ddx operator C dei dq dei di Tf i Tf dq i = = τ f and C jci Tr dci = τ r dv BE V BC dq dei di Tf dv BE V T dv BC V BE V T Use of τ f0 instead of τ f partially compensates for overestimation of g m by ideal value i Tf /V T AP, MS 3

4 Lateral NQS modeling (cont d) Lateral NQS modeling (cont d) Application of simplified model (SiGe HBT with f T = 350 GHz) V BE Strongly reduced code size (ADS): 2.3 MB (v2.30) vs. 0.3 MB(2.31) => Faster compilation and execution of code Note: this change is not backwards compatible AP, MS 4

5 Lateral NQS modeling (cont d) pnp transistor option switching between npn and pnp-type addition of type-flag: 1 => npn (default), -1 => pnp verified DC, AC, transient and noise characteristics AP, MS 5

6 Operating point values in HICUM Operating point variables Name defined in HICUM/L2 manual aligned with SPICE standard reference implementation in vacode Large computational effort in code -> flags available: `ifdef CALC_OP `ifdef OP_STATIC if (analysis("static")) begin: OPERATING_POINT `else begin: OPERATING_POINT `endif for best perfomance: undef. CALC_OP -> no calculations def. OP_STATIC -> no calculation during transient simulations IB IC IS IAVL VBE VBC VCE VSC BETADC GMi GMS RPIi RPIx RMUi RMUx ROi Lateral NQS modeling (cont d) Name CPIi CPIx CMUi CMUx CCS RBI RB RCX RE BETAAC CRBI TF FT TK DTSH AP, MS 6

7 Now operating point values Now operating point values TK: actual device temperature in Kelvin DTSH: temperature increase due to self-heating Increase of ambient temperature TK (K) DTSH (K) Increase of ambient temperature V (V) BE V BE (V) AP, MS 7

8 Physical constants Physical constants Request by simulator vendor to include values of physical constants in model code Advantage no dependence on different values in different simulators => same results of compact model results in all simulators Disadvantage possibly different results for same characteristics (e.g. base current) from different compact models with same formulation and parameters in same simulator due to different values of k B and q Will nevertheless be available in future releases AP, MS 8

9 Feature requests Feature requests Neutral base recombination request for implementation into HICUM/L2 physics-based model equation I NBRS = I NBRS0 [ 1 k b ( c 1) ] with c = C jci0 C jci and a constant k b I B (μa) meas model V CB (V) AP, MS 9

10 Feature requests Improved substrate capacitance modeling Adding a perimeter related substrate capacitance without coupling network attached => directly between external C and S Allow junction (variable) and DTI (constant) capacitance Incorporation into HICUM/L2 no additional node required => simple addition requires bias and temperature dependent capacitances for perimeter junction related component b bl STI n + b.l. C jsb b bl STI n + b.l. b CS SiO 2 C jsp y jbl p - b DTI SiO 2 p + p + Also improves intra-device substate coupling (with proper network added) C jsb C jsp p + AP, MS 10

11 Feature requests Removing the internal HICUM/L2 loop Originally suggested and feasibility demonstrated in [1] Method Adding a volt. source with V=0 in I Tf branch => source current I Tp is a solution variable make Q pt a function of I Tp instead of I T => derivative dq pt /I Tp generated by compiler and present internal loop can be omitted MNA forces I Tp = I Tf => iteration for I Tp during MNA solution implementated in test code to be fully tested for production [1] Z. Huszka, E. Seebacher, "Removing the Internal Iteration Loop from Hicum/L2", 9 th HICUM Workshop, Germany, AP, MS 11

12 Feature requests Implementation results Note: no production implementation, removed ICH and TR Code reduction: 857 kb -> 527 kb (FORTRAN source code) Test case for forward gummel plots at different V BC, (- loop, o - no loop) x I C, I B (A) f T, f max (GHz) V BE (V) I C (A) iterations operations 3 x V (V) BE V (V) BE AP, MS 12

Modeling high-speed SiGe-HBTs with HICUM/L2 v2.31

Modeling high-speed SiGe-HBTs with HICUM/L2 v2.31 A. Pawlak, M. Schroter, A. Mukherjee, J. Krause Chair for Electron Devices and Integrated Circuits (CEDIC) Technische Universität Dresden, Germany pawlak@iee.et.tu-dresden.de,