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SPICE Model for Magnetic Tunnel Junctions

xiaoweishawn

I am trying to find a good model for magnetic tunnel junction(MTJ) that could work in Cadence to do simulation. BTW, MTJ is a new device and has no present models in cadence like nefet or pfet. I happended to find this one nanohub.org/.../SPICE_Model_Manual.pdf​ which seems quite promising.

according to what said on the webpage, the model file includes 6 files: LLG.lib, LLGThermRandNum.va, MTJ.lib, MTJ_res.va, NRL_MTJspice_ENC_LIB.inc and USUAGE( these files could be found  nanohub.org/.../19048, then under the supporting Docs column). 

My question is what might  these six files for and how could I performe simulation with these six files in cadence?

I am a beginner in cadence, not sure whether I express myself clear or not. Thanks so much for your possible help!

Bless. 

 

Parents

  • Hi, Quek.

    How can I use the two va files, what are their functions: LLGThermRandNum.va and MTJ_res.va  

    the LLGThermRandNum.va's content is like this:

    // Creator: Xuanyao Fong

    // Email: xfong@purdue.edu

    // Contributors: Xuanyao Fong

    // This block generates random numbers for use with the LLG thermal

    // fluctuation calculations


    `include "disciplines.vams"

    `include "constants.vams"


    module ThermRandNumBlk(t1);

    output t1;

    electrical t1; //External Terminals of the resistor


    integer seedVal;


    analog begin : res_module


    V(t1) <+ $rdist_normal(seedVal, 0.0, 1.0);


    end


    endmodule

     

    and the MTJ_res.va file is like this:\

     

    // Creator: Harsha Choday

    // Email: schoday@purdue.edu

    // Contributors: Xuanyao Fong

    // This file is a copy of MTJ_QCOM5_res.va with added comment lines

    // Resistance model of MTJ with physical params:

    // Eb=0.8, delta=0.75, m_fm=0.735, m_ox=0.74, Ms=800, Ku2=30000

    // This file and the coefficients for fitting equation generated by MATLAB


    `include "disciplines.vams"

    `include "constants.vams"


    module MTJ_res(t1,t2,MTJ_curr,th,phi,th_hard,phi_hard);

    inout t1,t2;

    input th,phi,th_hard,phi_hard;

    output MTJ_curr;

    electrical t1,t2,MTJ_curr,th,phi,th_hard,phi_hard; //External Terminals of the resistor


    // Coefficients for fitting Rap

    parameter real c1_ap = -6.7524 from (-inf:inf);

    parameter real c2_ap = 23.2848 from (-inf:inf);

    parameter real c3_ap = -7.56891 from (-inf:inf);

    parameter real c4_ap = 24.144 from (-inf:inf);

    parameter real c5_p = 1 from (-inf:inf);


    // Coefficients for fitting Rp

    parameter real c1_p = -5.90497 from (-inf:inf);

    parameter real c2_p = 21.5434 from (-inf:inf);

    parameter real c3_p = -7.46919 from (-inf:inf);

    parameter real c4_p = 25.0243 from (-inf:inf);

    parameter real c5_ap = 1 from (-inf:inf);


    parameter real Tox = 1.15 from (-inf:inf);

    parameter real Area = 3.6298e-15 from (-inf:inf); // 0.25*3.14*2.89*40e-9*40e-9 m2

    (* desc="MTJ Resistances", units="Ohm" *) real Gp, Gap, Gmtj, Rmtj, mdp;


    analog begin : res_module


    real Gp_pre, Gap_pre;


    mdp = (sin(V(th))*cos(V(th))*sin(V(th_hard))*cos(V(phi_hard))) + (sin(V(th))*sin(V(phi))*sin(V(th_hard))*sin(V(phi_hard))) + (cos(V(th))*cos(V(th_hard)));


    Gp_pre = exp(c1_p*Tox + c2_p)*pow(V(t1,t2),2) + exp(c3_p*Tox + c4_p); // Polynomial gives G/A

    Gap_pre = exp(c1_ap*Tox + c2_ap)*pow(V(t1,t2),2) + exp(c3_ap*Tox + c4_ap);


    Gp = (pow(Gp_pre,1))*(Area*1e4); // Apply term_pow and multiply area to obtain conductance

    Gap = (pow(Gap_pre,1))*(Area*1e4);


    Gmtj = Gap + (mdp+1)*0.5*(Gp-Gap);

    Rmtj = pow(Gmtj,-1);


    I(t1,t2) <+ V(t1,t2)/Rmtj;

    V(MTJ_curr) <+ -V(t2,t1)/Rmtj;

    end


    endmodule

     

     

    Thanks a lot!!!  

Reply

  • Hi, Quek.

    How can I use the two va files, what are their functions: LLGThermRandNum.va and MTJ_res.va  

    the LLGThermRandNum.va's content is like this:

    // Creator: Xuanyao Fong

    // Email: xfong@purdue.edu

    // Contributors: Xuanyao Fong

    // This block generates random numbers for use with the LLG thermal

    // fluctuation calculations


    `include "disciplines.vams"

    `include "constants.vams"


    module ThermRandNumBlk(t1);

    output t1;

    electrical t1; //External Terminals of the resistor


    integer seedVal;


    analog begin : res_module


    V(t1) <+ $rdist_normal(seedVal, 0.0, 1.0);


    end


    endmodule

     

    and the MTJ_res.va file is like this:\

     

    // Creator: Harsha Choday

    // Email: schoday@purdue.edu

    // Contributors: Xuanyao Fong

    // This file is a copy of MTJ_QCOM5_res.va with added comment lines

    // Resistance model of MTJ with physical params:

    // Eb=0.8, delta=0.75, m_fm=0.735, m_ox=0.74, Ms=800, Ku2=30000

    // This file and the coefficients for fitting equation generated by MATLAB


    `include "disciplines.vams"

    `include "constants.vams"


    module MTJ_res(t1,t2,MTJ_curr,th,phi,th_hard,phi_hard);

    inout t1,t2;

    input th,phi,th_hard,phi_hard;

    output MTJ_curr;

    electrical t1,t2,MTJ_curr,th,phi,th_hard,phi_hard; //External Terminals of the resistor


    // Coefficients for fitting Rap

    parameter real c1_ap = -6.7524 from (-inf:inf);

    parameter real c2_ap = 23.2848 from (-inf:inf);

    parameter real c3_ap = -7.56891 from (-inf:inf);

    parameter real c4_ap = 24.144 from (-inf:inf);

    parameter real c5_p = 1 from (-inf:inf);


    // Coefficients for fitting Rp

    parameter real c1_p = -5.90497 from (-inf:inf);

    parameter real c2_p = 21.5434 from (-inf:inf);

    parameter real c3_p = -7.46919 from (-inf:inf);

    parameter real c4_p = 25.0243 from (-inf:inf);

    parameter real c5_ap = 1 from (-inf:inf);


    parameter real Tox = 1.15 from (-inf:inf);

    parameter real Area = 3.6298e-15 from (-inf:inf); // 0.25*3.14*2.89*40e-9*40e-9 m2

    (* desc="MTJ Resistances", units="Ohm" *) real Gp, Gap, Gmtj, Rmtj, mdp;


    analog begin : res_module


    real Gp_pre, Gap_pre;


    mdp = (sin(V(th))*cos(V(th))*sin(V(th_hard))*cos(V(phi_hard))) + (sin(V(th))*sin(V(phi))*sin(V(th_hard))*sin(V(phi_hard))) + (cos(V(th))*cos(V(th_hard)));


    Gp_pre = exp(c1_p*Tox + c2_p)*pow(V(t1,t2),2) + exp(c3_p*Tox + c4_p); // Polynomial gives G/A

    Gap_pre = exp(c1_ap*Tox + c2_ap)*pow(V(t1,t2),2) + exp(c3_ap*Tox + c4_ap);


    Gp = (pow(Gp_pre,1))*(Area*1e4); // Apply term_pow and multiply area to obtain conductance

    Gap = (pow(Gap_pre,1))*(Area*1e4);


    Gmtj = Gap + (mdp+1)*0.5*(Gp-Gap);

    Rmtj = pow(Gmtj,-1);


    I(t1,t2) <+ V(t1,t2)/Rmtj;

    V(MTJ_curr) <+ -V(t2,t1)/Rmtj;

    end


    endmodule

     

     

    Thanks a lot!!!  

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