Dear Amit
Is V1 the voltage across R1 and V2 the voltage across R2? or are they independent other node voltages? The answer of the question depends on your reply.
wish you success.
Dear Amit,
Your question i very interesting and not a trivial one. It concerns the nonlinear sources in the SPICE. The answer is in using the nonlinear sources.
You have a resistance say R1 which is proportional to the voltage V1 between the nodes N1 and N2. The resistor R1 itself is connected between Nodes N3 and N4.
The relation is R1= a V1, Applying ohms law on the resistance R1, then V= I R1= a I V1, So, from this equation the voltage across R1 is proportional to ITS current I and the oltave V1. According to spice syntax one can substitute the current I by a SENSE VOLTAGE SOURCE VSENSE BETWEEN NODES 5 AND 6 in series with the resistance R1. Then the voltage source repressing the resistance R1 can be expressed by V = a *I(VSENSE)* V1,
This voltage dependent voltage source with two degrees of freedoms can be represented in SPICE according to the syntax:
EXXXXXX N3 N4 POLY2 N1 N2 N5 N6 0 0 0 O a
Where the polynomial coefficient are all zeros except p4=a = 10 in your example.
For more syntax of the SPICE you can consult any text book on SPICE as WALTER BANZHAF, computer aided analysis using SPICE.
If you have any questions please asK
wish you success.
Dear Sir
Thank you for the answer.I want to implement the circuit using spice as attached with this.
Here the value of R1=(CR1 + CR2*cos(CF1*V(2,3)))
where CR1,CR2,CF1 are constant values
V(2,3) is the potential across node 2 and 3.
Dear Amit,
You challenge me with your questions.
Since the cosine can be expressed by the polynomial:
cos x = 1 - x^2/ 2! + x^4/4! - x^6/ 6! + ..., about terms are sufficient to calculate the cos accurately. with x is CF1*V(2,3),
then R1= CR1 + CR2 - CR2 x^2/ 2! + CR2 x^4/4! - CR2 x^6/ 6! + neglected terms,
Substituting for x, then we get finally,
R1= CR1 + CR2 - CR2 CR1^2 V(2,3)^2,/ 2! + CR2 CR1^4 V(2,3)^4/ 4! - CR2 CR1^6 V(2,3)^6/ 6!,
This polynomial has the standard form
R =p0- p2 V(2,3)^2+ P4 V(2,3)^4- p6V(2,3)^6
This resistor can be implemented as indicated before as a nonlinear constant voltage source with wth POLY2.
wish you success.
Dear Amit,
voltage and current sources which are controlled by a generic mathematical function of one or more voltages/currents available in a circuit can be defined as "B" (which I suppose stands for "behavioral") components in Spice. Here some examples:
B1 0 1 I=cos(v(1))+sin(v(2))
B1 0 1 V=ln(cos(log(v(1,2)^2)))-v(3)^4+v(2)^v(1)
B1 3 4 I=17
B1 3 4 V=exp(pi^i(vdd))...
please refer to Berkley's Spice online documentation for further details.
http://bwrcs.eecs.berkeley.edu/Classes/IcBook/SPICE/UserGuide/elements_fr.html
I believe your nonlinear resistor is best described as
VSENSE N4 N5 0
B1 N3 N4 V=(CR1 + CR2*cos(CF1*V(2,3)))*I(VSENSE)
being VSENSE a 0V sense voltage source in series with the resistor to be implemented, as previously suggested.
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