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Diffstat (limited to 'src/lib/netlist/analog/nld_mosfet.cpp')
-rw-r--r-- | src/lib/netlist/analog/nld_mosfet.cpp | 488 |
1 files changed, 488 insertions, 0 deletions
diff --git a/src/lib/netlist/analog/nld_mosfet.cpp b/src/lib/netlist/analog/nld_mosfet.cpp new file mode 100644 index 00000000000..ea717fdefee --- /dev/null +++ b/src/lib/netlist/analog/nld_mosfet.cpp @@ -0,0 +1,488 @@ +// license:GPL-2.0+ +// copyright-holders:Couriersud +/* + * nld_mosfet.cpp + * + * Formulas in here based on the following Sources: + * + * https://www.imperial.ac.uk/pls/portallive/docs/1/7292573.PDF + * http://www3.imperial.ac.uk/pls/portallive/docs/1/56133736.PDF + * https://people.rit.edu/lffeee/SPICE_MOSFET_Model_Intro.pdf + * https://people.rit.edu/lffeee/SPICE.pdf + * http://web.mit.edu/course/6/6.012/SPR98/www/lectures/S98_Lecture10.pdf + * http://homepages.rpi.edu/~sawyes/Models_review.pdf + * http://jaco.ec.t.kanazawa-u.ac.jp/edu/mix/pdf/3.pdf + * + * Farid N. Naim, Circuit Simulation (Wiley-IEEE Press, 2010). + * Stefan Jahn, Michael Margraf, Vincent Habchi and Raimund Jacob, "Qucs Technical Papers" (2007) + * + */ + +#include "netlist/solver/nld_solver.h" +#include "netlist/nl_setup.h" +#include "nlid_twoterm.h" + +#include <cmath> + +#define BODY_CONNECTED_TO_SOURCE (1) + +namespace netlist +{ +namespace analog +{ + + using constants = plib::constants<nl_double>; + + // ----------------------------------------------------------------------------- + // nld_FET - Base classes + // ----------------------------------------------------------------------------- + + /*! Class representing the nmos model paramers. + * + * This is the model representation of the nmos model. Typically, SPICE uses + * the following parameters. A "Y" in the first column indicates that the + * parameter is actually used in netlist. + * + * | NL? |Name | Description|Units |Default |Example | + * |:---:|------|-----------------------------------------------------------------------|-------|---------:|----------------:| + * | Y |Vto | Zero-bias threshold voltage | V | 0 | 1 | + * | Y |Kp | Transconductance parameter | A/V² | 0.00002 | 0.00003 | + * | Y |Gamma | Bulk threshold parameter | V^½ | 0 | 0.37 | + * | Y |Phi | Surface inversion potential | V | 0.6 | 0.65 | + * | Y |Lambda| Channel-length modulation (level 1 and 2 only) | 1/V | 0 | 0.02 | + * | |Rd | Drain ohmic resistance |W|0|1| + * | |Rs | Source ohmic resistance |W|0|1| + * | |Cbd | Zero-bias B-D junction capacitance |F|0|20f| + * | |Cbs | Zero-bias B-S junction capacitance |F|0|20f| + * | Y |Is | Bulk junction saturation current |A|0.00000000000001|1E-015| + * | Y |N | Bulk diode emission coefficient |-|1|* + * | |Pb | Bulk junction potential |V|0.8|0.87|8| + * | |Cgso | Gate-source overlap capacitance per meter channel width |F/m|0|0.00000000004| + * | |Cgdo | Gate-drain overlap capacitance per meter channel width |F/m|0|0.00000000004|* + * | |Cgbo | Gate-bulk overlap capacitance per meter channel width |F/m|0|0.0000000002|* + * | |Rsh | Drain and source diffusion sheet resistance |W|0|10|* + * | |Cj | Zero-bias bulk junction bottom capacitance per square meter of junction area|F/m²|0|0.0002|* + * | |Mj | Bulk junction bottom grading coefficient |-|0.5|0.5|* + * | |Cjsw | Zero-bias bulk junction sidewall capacitance per meter of junction perimeter|F/m|0|1p|* + * | |Mjsw | Bulk junction sidewall grading coefficient |-|.50 level 1 .33 level 2,3|| + * | |Js | Bulk junction saturation current per square-meter of junction area|A/m|0|0.00000001| + * | Y |Tox | Oxide thickness |m|0.0000001|0.0000001| + * | Y |Nsub | Substrate doping |1/cm³|0|4000000000000000| + * | |Nss | Surface state density |1/cm²|0|10000000000| + * | |Nfs | Fast surface state |1/cm²|0|10000000000|* + * | |TPG | Type of gate material: +1 opp. to substrate -1 same as substrate 0 Al gate|-|1| + * | |Xj | Metallurgical junction depth |m|0|1µ|* + * | Y |Ld | Lateral diffusion |m|0|0.8µ| + * | Y |Uo | Surface mobility |cm²/V/s|600|700| + * | |Ucrit | Critical field for mobility degradation (level 2 only) |V/cm|10000|10000| + * | |Uexp | Critical field exponent in mobility degradation (level 2 only) |-|0|0.1| + * | |Utra | Transverse field coefficient (level 2 only) |-|0|0.3|* + * | |Vmax | Maximum carrier drift velocity (levels 2 & 3 only) |m/s|0|50000| + * | |Neff | Total channel-charge exponent (level 2 only) |-|1|5| + * | |Kf | Flicker noise coefficient |-|0|1E-026| + * | |Af | Flicker noise exponent |-|1|1.2| + * | |Fc | Coefficient for forward-bias depletion capacitance formula |-|0.5| + * | |Delta | Width effect on threshold voltage(levels 2 and 3) |-|0|1| + * | |Theta | Mobility modulation (level 3 only) |-|0|0.1| + * | |Eta | Static feedback (level 3 only) |-|0|1| + * | |Kappa | Saturation field (level 3 only) |0.2|0.5| + * | |Tnom | Parameter measurement temperature |ºC|27|50|| + * | Y |L | Length scaling |-|1.0|| + * | Y |W | Width scaling |-|1.0|| + * */ + + class fet_model_t : public param_model_t + { + public: + fet_model_t(device_t &device, const pstring &name, const pstring &val) + : param_model_t(device, name, val) + , m_VTO(*this, "VTO") + , m_N(*this, "N") + , m_ISS(*this, "IS") // Haven't seen a model using ISS / ISD + , m_ISD(*this, "IS") + , m_LD(*this, "LD") + , m_L(*this, "L") + , m_W(*this, "W") + , m_TOX(*this, "TOX") + , m_KP(*this, "KP") + , m_UO(*this, "UO") + , m_PHI(*this, "PHI") + , m_NSUB(*this, "NSUB") + , m_GAMMA(*this, "GAMMA") + , m_LAMBDA(*this, "LAMBDA") + , m_RD(*this, "RD") + , m_RS(*this, "RS") + {} + + value_t m_VTO; //!< Threshold voltage [V] + value_t m_N; //!< Bulk diode emission coefficient + value_t m_ISS; //!< Body diode saturation current + value_t m_ISD; //!< Body diode saturation current + value_t m_LD; //!< Lateral diffusion [m] + value_t m_L; //!< Length scaling + value_t m_W; //!< Width scaling + value_t m_TOX; //!< Oxide thickness + value_t m_KP; //!< Transconductance parameter [A/V²] + value_t m_UO; //!< Surface mobility [cm²/V/s] + value_t m_PHI; //!< Surface inversion potential [V] + value_t m_NSUB;//!< Substrate doping [1/cm³] + value_t m_GAMMA; //!< Bulk threshold parameter [V^½] + value_t m_LAMBDA; //!< Channel-length modulation [1/V] + value_t m_RD; //!< Drain ohmic resistance + value_t m_RS; //!< Source ohmic resistance + }; + + // Have a common start for mosfets + + NETLIB_OBJECT(FET) + { + public: + enum q_type { + FET_NMOS, + FET_PMOS + }; + + NETLIB_CONSTRUCTOR(FET) + , m_model(*this, "MODEL", "NMOS") + , m_qtype(FET_NMOS) + { + } + + NETLIB_IS_DYNAMIC(true) + + //NETLIB_RESETI(); + NETLIB_UPDATEI() { } + + q_type qtype() const { return m_qtype; } + bool is_qtype(q_type atype) const { return m_qtype == atype; } + void set_qtype(q_type atype) { m_qtype = atype; } + protected: + + fet_model_t m_model; + private: + q_type m_qtype; + }; + + // ----------------------------------------------------------------------------- + // nld_QBJT_EB + // ----------------------------------------------------------------------------- + + + NETLIB_OBJECT_DERIVED(MOSFET, FET) + { + public: + NETLIB_CONSTRUCTOR_DERIVED(MOSFET, FET) + , m_DG(*this, "m_DG", true) + , m_SG(*this, "m_SG", true) + , m_SD(*this, "m_SD", true) + , m_D_BD(*this, "m_D_BD") +#if (!BODY_CONNECTED_TO_SOURCE) + , m_D_BS(*this, "m_D_BS") +#endif + , m_phi(0.0) + , m_gamma(0.0) + , m_vto(0.0) + , m_beta(0.0) + , m_lambda(0.0) + , m_Leff(0.0) + , m_Cox(0.0) + { + register_subalias("S", m_SG.m_P); // Source + register_subalias("G", m_SG.m_N); // Gate + + register_subalias("D", m_DG.m_P); // Drain + + connect(m_SG.m_P, m_SD.m_P); + connect(m_SG.m_N, m_DG.m_N); + connect(m_DG.m_P, m_SD.m_N); + +#if 0 + if (m_model.m_CJE > 0.0) + { + create_and_register_subdevice("m_CJE", m_CJE); + connect("B", "m_CJE.1"); + connect("E", "m_CJE.2"); + } + if (m_model.m_CJC > 0.0) + { + create_and_register_subdevice("m_CJC", m_CJC); + connect("B", "m_CJC.1"); + connect("C", "m_CJC.2"); + } +#endif + } + + protected: + + NETLIB_RESETI(); + NETLIB_UPDATEI(); + NETLIB_UPDATE_PARAMI(); + NETLIB_UPDATE_TERMINALSI(); + + private: + + nld_twoterm m_DG; + nld_twoterm m_SG; + nld_twoterm m_SD; + + generic_diode<diode_e::MOS> m_D_BD; +#if (!BODY_CONNECTED_TO_SOURCE) + generic_diode<diode_e::MOS> m_D_BS; +#endif + + nl_double m_phi; + nl_double m_gamma; + nl_double m_vto; + nl_double m_beta; + nl_double m_lambda; + + /* used in capacitance calculation */ + nl_double m_Leff; + nl_double m_Cox; + + //NETLIB_SUBXX(analog, C) m_CJE; + //NETLIB_SUBXX(analog, C) m_CJC; + }; + + + + // ---------------------------------------------------------------------------------------- + // nld_Q - Ebers Moll + // ---------------------------------------------------------------------------------------- + + + NETLIB_UPDATE(MOSFET) + { + if (!m_SG.m_P.net().isRailNet()) + m_SG.m_P.solve_now(); // Basis + else if (!m_SG.m_N.net().isRailNet()) + m_SG.m_N.solve_now(); // Emitter + else + m_DG.m_N.solve_now(); // Collector + } + + NETLIB_RESET(MOSFET) + { + NETLIB_NAME(FET)::reset(); +#if 0 + if (m_CJE) + { + m_CJE->reset(); + m_CJE->m_C.setTo(m_model.m_CJE); + } + if (m_CJC) + { + m_CJC->reset(); + m_CJC->m_C.setTo(m_model.m_CJC); + } +#endif + } + + NETLIB_UPDATE_TERMINALS(MOSFET) + { + const nl_double polarity = (qtype() == FET_NMOS ? 1.0 : -1.0); + + const nl_double Ugd = -m_DG.deltaV() * polarity; // Gate - Drain + const nl_double Ugs = -m_SG.deltaV() * polarity; // Gate - Source + const nl_double Ubs = 0.0; // Bulk - Source == 0 if connected + const nl_double Ubd = m_SD.deltaV() * polarity; // Bulk - Drain = Source - Drain + const nl_double Uds = Ugs - Ugd; + +#if (!BODY_CONNECTED_TO_SOURCE) + m_D_BS.update_diode(Ubs); +#endif + m_D_BD.update_diode(Ubd); + + // Are we in forward mode ? + const bool is_forward = Uds >= 0; + + // calculate Vth + const nl_double Vbulk = is_forward ? Ubs : Ubd; + const nl_double phi_m_Vbulk = (m_phi > Vbulk) ? std::sqrt(m_phi - Vbulk) : 0.0; + const nl_double Vth = m_vto * polarity + m_gamma * (phi_m_Vbulk - std::sqrt(m_phi)); + + const nl_double Vctrl = (is_forward ? Ugs : Ugd) - Vth; + + nl_double Ids, gm, gds, gmb; + + if (Vctrl <= 0.0) + { + // cutoff region + Ids = 0.0; + gm = 0.0; + gds = 0.0; + gmb = 0.0; + } + else + { + const nl_double Vds = std::abs(Uds); + const nl_double b = m_beta * (1.0 + m_lambda * Vds); + if (Vctrl <= Vds) + { + // saturation region + Ids = b * Vctrl * Vctrl / 2.0; + gm = b * Vctrl; + gds = m_lambda * m_beta * Vctrl * Vctrl / 2.0; + } + else + { + // linear region + Ids = b * Vds * (Vctrl - Vds / 2); + gm = b * Vds; + gds = b * (Vctrl - Vds) + m_lambda * m_beta * Vds * (Vctrl - Vds / 2.0); + } + + // backgate transconductance + const nl_double bgtc = (phi_m_Vbulk != 0.0) ? (m_gamma / phi_m_Vbulk / 2.0) : 0.0; + gmb = gm * bgtc; + } + + // FIXME: these are needed to compute capacitance + // nl_double Udsat = pol * std::max (Utst, 0.0); + // Uon = pol * Vth; + + // compute bulk diode equivalent currents + + const nl_double IeqBD = m_D_BD.Ieq(); + const nl_double gbd = m_D_BD.G(); +#if 0 + const nl_double IeqBS = m_D_BS.Ieq(); + const nl_double gbs = m_D_BS.G(); +#else + const nl_double IeqBS = 0.0; + const nl_double gbs = 0.0; +#endif + // exchange controlling nodes if necessary + const nl_double gsource = is_forward ? (gm + gmb) : 0; + const nl_double gdrain = is_forward ? 0.0 : (gm + gmb); + + const nl_double IeqDS = (is_forward) ? + Ids - gm * Ugs - gmb * Ubs - gds * Uds + : -Ids - gm * Ugd - gmb * Ubd - gds * Uds; + + // IG = 0 + const nl_double IG = 0.0; + const nl_double ID = (+IeqBD - IeqDS) * polarity; + const nl_double IS = (+IeqBS + IeqDS) * polarity; + const nl_double IB = (-IeqBD - IeqBS) * polarity; + + const nl_double gGG = 0.0; // ok + const nl_double gGD = 0.0; // ok + const nl_double gGS = 0.0; // ok + const nl_double gGB = 0.0; // ok + + const nl_double gDG = gm; // ok + const nl_double gDD = gds + gbd - gdrain; // ok + const nl_double gDS = -gds - gsource; // ok + const nl_double gDB = gmb - gbd; // ok + + const nl_double gSG = -gm; // ok + const nl_double gSD = -gds + gdrain; // ok + const nl_double gSS = gbs + gds + gsource; // ok + const nl_double gSB = -gbs - gmb; + + const nl_double gBG = 0.0; // ok + const nl_double gBD = -gbd; // ok + const nl_double gBS = -gbs; + const nl_double gBB = gbs + gbd; // ok + + // Source connected to body, Diode S-B shorted! + const nl_double gSSBB = gSS + gBB + gBS + gSB; + + // S G + m_SG.set_mat( gSSBB, gSG + gBG, +(IS + IB), // S + gGS + gGB, gGG, IG ); // G + // D G + m_DG.set_mat( gDD, gDG, +ID, // D + gGD, 0.0, 0.0 ); // G + // S D + m_SD.set_mat( 0.0, gSD + gBD, 0.0, // S + gDS + gDB, 0.0, 0.0); // D + + } + + + NETLIB_UPDATE_PARAM(MOSFET) + { + set_qtype((m_model.model_type() == "NMOS") ? FET_NMOS : FET_PMOS); + + /* + * From http://ltwiki.org/LTspiceHelp/LTspiceHelp/M_MOSFET.htm : + * + * VTO, KP, LAMBDA, PHI and GAMMA. These parameters are computed + * if the process parameters(NSUB, TOX,...) are given, but + * user-specified values always override. + * + * But couldn't find a formula for lambda anywhere + * + */ + + m_lambda = m_model.m_LAMBDA; // FIXME: m_lambda only set once + + // calculate effective channel length + m_Leff = m_model.m_L - 2 * m_model.m_LD; + nl_assert_always(m_Leff > 0.0, "Effective Lateral diffusion would be negative for model " + m_model.name()); + if (m_model.m_TOX > 0.0) + m_Cox = (constants::eps_SiO2() * constants::eps_0() / m_model.m_TOX); + else + m_Cox = 0.0; + + // calculate DC transconductance coefficient + if (m_model.m_KP > 0) + m_beta = m_model.m_KP * m_model.m_W / m_Leff; + else if (m_Cox > 0 && m_model.m_UO > 0) + m_beta = m_model.m_UO * 1e-4 * m_Cox * m_model.m_W / m_Leff; + else + m_beta = 2e-5 * m_model.m_W / m_Leff; + + // Bulk diodes + + m_D_BD.set_param(m_model.m_ISD, m_model.m_N, exec().gmin(), constants::T0()); +#if (!BODY_CONNECTED_TO_SOURCE) + m_D_BS.set_param(m_model.m_ISS, m_model.m_N, exec().gmin(), constants::T0()); +#endif + + //FIXME::UT can disappear + const double Vt = constants::T0() * constants::k_b() / constants::Q_e(); + + // calculate surface potential if not given + + if (m_model.m_PHI > 0.0) + m_phi = m_model.m_PHI; + else if (m_model.m_NSUB > 0.0) + { + nl_assert_always(m_model.m_NSUB * 1e6 >= constants::NiSi(), "Error calculating phi for model " + m_model.name()); + m_phi = 2 * Vt * std::log (m_model.m_NSUB * 1e6 / constants::NiSi()); + } + else + m_phi = 0.6; + + // calculate bulk threshold if not given + if (m_model.m_GAMMA > 0.0) + m_gamma = m_model.m_GAMMA; + else + { + if (m_Cox > 0 && m_model.m_NSUB > 0) + m_gamma = std::sqrt (2.0 * constants::Q_e() * constants::eps_Si() * constants::eps_0() * m_model.m_NSUB * 1e6) / m_Cox; + else + m_gamma = 0.0; + } + + m_vto = m_model.m_VTO; + nl_assert_always(m_vto != 0.0, "Threshold voltage not specified for " + m_model.name()); + + /* FIXME: VTO if missing may be calculated from TPG, NSS and temperature. Usually models + * specify VTO so skip this here. + */ + + m_Cox = m_Cox * m_model.m_W * m_Leff; + + } + +} // namespace analog + +namespace devices { + NETLIB_DEVICE_IMPL_NS(analog, MOSFET, "MOSFET", "MODEL") +} // namespace devices + +} // namespace netlist |