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Modeling >> Behavioral Models >> Simple Inductor model in SystemVerilog using Cadence EEnet
https://designers-guide.org/forum/YaBB.pl?num=1601665503

Message started by sanforyou on Oct 2^nd, 2020, 12:05pm

Title: Simple Inductor model in SystemVerilog using Cadence EEnet
Post by sanforyou on Oct 2^nd, 2020, 12:05pm

I have a simple SV capacitor model using EEnet as shown below. This simulates with no issues when driven by 1V square wave as shown below:

Code:

`timescale 1ns/1ps
import EE_pkg::*;

module CapGeq ( P );

inout EEnet P;
parameter real c=1e-9; // capacitance
parameter real rs=0; // series resistance
parameter real ic=0; // initial capacitor voltage at time zero
parameter real tinc=10e-9; // timestep for computing voltage update (sec)

bit ck;
real dV,Icap,Tcap, Vout;

always #(tinc*1s) ck=!ck; //toggle clock at defined rate

always@(P.I,ck) begin //on input change or clock cycle;
dV=Icap*($realtime-Tcap)/(c*1s); //voltage change is I*DT/C
Icap=P.I; Tcap=$realtime; //save new current and time
Vout += dV; //update voltage
end

assign P='{Vout,0,0}; //drive output as ideal voltage source

endmodule

Output waveform is also attached for capacitor

However I try to replicate inductor SV model using similar strategy as shown below:

Code:

`timescale 1ns/1ps
import EE_pkg::*;
import cds_rnm_pkg::*;

module indGeq(P);
inout EEnet P;

parameter real L=50e-6; // inductunce, 50uH
parameter real rs=0; // series resistance
parameter real iL=0; // initial inductor voltage at time zero
parameter real tinc=1e-9; // timestep for computing voltage update (sec)

bit ck;
real dI,Vind,Tind,Iout;

//initial Vind=iL;

always #(tinc*1s) ck=!ck;

always @(P.V,ck) begin //on input change or clock cycle;
dI=Vind*($realtime-Tind)/(L*1s); //current change is Vind*dt/L;
Vind=P.V; //save new voltage
Tind=$realtime; //save new time
Iout+=dI; //update current
end

assign P = '{0,Iout,0}; //drive output as ideal current source

endmodule

However, I see "Iout" and Vind both are zero all the time as shown in Inductor output waveforms. Can anyone explain why this model is not working?

Title: Re: Simple Inductor model in SystemVerilog using Cadence EEnet
Post by sanforyou on Oct 2^nd, 2020, 12:06pm

Also here are Inductor simulation waveforms

Title: Re: Simple Inductor model in SystemVerilog using Cadence EEnet
Post by Geoffrey_Coram on Oct 29^th, 2020, 7:44am

I have never used EEnet. Is it a Cadence-specific thing? I don't know what it means when you

Code:

assign P = '{0, Iout, 0};

Have you tried putting in some print statements to debug? I assume Vind starts at 0, so that on the first step, dI = 0. How are you driving this model? Can you print P.V and verify that it is being driven?