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Circuit 10: Josephson Gap Potential Modulation

    WRspice jj qp modulation demo
    *
    * The rtype=4 option of the Josephson model causes the gap potential
    * to scale with the external "control current" absolute value.  For
    * unit control current (1 Amp) or larger, the full potential is used,
    * otherwise it scales linearly to zero.  The transfer function is defined
    * externally with controlled sources, as below.  The approximation
    * Vg = Vg0*(1-t**4) is pretty good, except near t = 1 (T = Tc, t = T/Tc).
    * The actual transfer function is left to the user - in the example below,
    * the ambient temperature is 7K, Tc=9.2K, and 1mv of "input" causes 1K
    * temperature shift.
    *
    * For amusement, change cct=1 to cct=0 below.  This runs much more quickly
    * as critical current is set to zero.
    *
    b1 1 0 jj1 control=v2
    v1 2 0 pulse(0 35m 10p 10p)
    r1 2 1 100
    *
    v2 3 0
    g1 3 0 4 0 function 1 - (1000*x+7)/9.2)^4
    v4 4 0 pulse(-1m 1m 10p 10p 10p 20p 60p)
    *
    *Nb 1000 A/cm2   area = 30 square microns
    .model jj1 jj(rtype=4,cct=1,icon=10m,vg=2.8m,delv=.1m,
    + icrit=0.3m,r0=100,rn=5.4902,cap=1.14195p)
    .tran 1p 500p uic
    * type "run", then plot v(1) and v(4) to see the gap shift and input
    .end



Stephen R. Whiteley 2017-11-08