2012-06-13 18:17:36 +02:00
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Memristor with threshold as XSPICE code model
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* Y. V. Pershin, M. Di Ventra: "SPICE model of memristive devices with threshold",
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* arXiv:1204.2600v1 [physics.comp-ph] 12 Apr 2012,
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* http://arxiv.org/pdf/1204.2600.pdf
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* XSPICE code model, parameter selection and plotting by
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* Holger Vogt 2012
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2012-06-09 18:25:51 +02:00
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* ac and op (dc) simulation just use start resistance rinit!
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2012-06-13 18:17:36 +02:00
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.param stime=10n
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2012-06-11 19:08:36 +02:00
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.param vmax = 4.2
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2012-06-13 18:17:36 +02:00
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* send parameters to the .control section
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.csparam stime={stime}
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.csparam vmax={vmax}
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*Xmem 1 0 memristor
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* triangular sweep (you have to adapt the parameters to 'alter' command in the .control section)
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*V1 1 0 DC 0 PWL(0 0 '0.25*stime' 'vmax' '0.5*stime' 0 '0.75*stime' '-vmax' 'stime' 0)
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2012-06-09 18:25:51 +02:00
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* sinusoidal sweep for transient, dc for op, ac
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V1 0 1 DC 0.1 ac 1 sin(0 'vmax' '1/stime')
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2012-06-13 18:17:36 +02:00
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2012-06-09 18:25:51 +02:00
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Rl 1 11 1k
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2012-06-13 18:17:36 +02:00
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* memristor model with limits and threshold
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* "artificial" parameters alpha, beta, and vt. beta and vt adapted to basic programming frequency
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* just to obtain nice results!
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* You have to care for the physics and set real values!
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2012-06-09 18:25:51 +02:00
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amen 11 2 memr
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2012-06-13 18:17:36 +02:00
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.model memr memristor (rmin=1k rmax=10k rinit=7k alpha=0 beta='20e3/stime' vt=1.6)
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vgnd 2 0 dc 0
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* This is the original subcircuit model
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.subckt memristor plus minus PARAMS: Ron=1K Roff=10K Rinit=7.0K alpha=0 beta=20e3/stime Vt=1.6
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Bx 0 x I='((f1(V(plus)-V(minus))> 0) && (V(x) < Roff)) ? {f1(V(plus)-V(minus))}: ((((f1(V(plus)-V(minus)) < 0) && (V(x)>Ron)) ? {f1(V(plus)-V(minus))}: 0)) '
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Vx x x1 dc 0
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Cx x1 0 1 IC={Rinit}
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Rmem plus minus r={V(x)}
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.func f1(y)={beta*y+0.5*(alpha-beta)*(abs(y+Vt)-abs(y-Vt))}
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.ends
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* transient simulation same programming voltage but rising frequencies
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.control
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*** first simulation ***
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2012-06-09 18:25:51 +02:00
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op
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print all
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ac lin 101 1 100k
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plot v(11)
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2012-06-13 18:17:36 +02:00
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* approx. 100 simulation points
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let deltime = stime/100
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tran $&deltime $&stime uic
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* plot i(v1) vs v(1)
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*** you may just stop here ***
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* raise the frequency
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2012-06-11 19:08:36 +02:00
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let newfreq = 1.2/stime
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let newstime = stime/1.2
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2012-06-13 18:17:36 +02:00
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let deltime = newstime/100
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alter @V1[sin] [ 0 $&vmax $&newfreq ]
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tran $&deltime $&newstime uic
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* raise the frequency even more
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let newfreq = 1.4/stime
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let newstime = stime/1.4
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let deltime = newstime/100
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alter @V1[sin] [ 0 $&vmax $&newfreq ]
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tran $&deltime $&newstime uic
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* the resistor currents
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plot tran1.alli tran2.alli alli title 'Memristor with threshold: currents'
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* calculate resistance (avoid dividing by zero)
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let res = v(1)/(I(v1) + 1e-16)
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let res1 = tran1.v(1)/(tran1.I(v1) + 1e-16)
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let res2 = tran2.v(1)/(tran2.I(v1) + 1e-16)
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* resistance versus time plot
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settype impedance res res1 res2
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plot res vs time res1 vs tran1.time res2 vs tran2.time title 'Memristor with threshold: resistance'
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* resistance versus voltage (change occurs only above threshold!)
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plot res vs v(1) res1 vs tran1.v(1) res2 vs tran2.v(1) title 'Memristor with threshold: resistance'
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* current through resistor for all plots versus voltage
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plot i(v1) vs v(1) tran1.i(v1) vs tran1.v(1) tran2.i(v1) vs tran2.v(1) title 'Memristor with threshold: external current loops'
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.endc
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.end
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