variabe capacitor in hspice

[admiral_v]

hi i decide simulate this circuit in hspice but i can't modeling variable capacitor section pleeeease helllp me

 

[dick_freebird]

Do you want to vary by simulator variable, by circuit voltage,
or what?

I suggest you look at whether veriloga is supported by your
HSPICE version and if so, scrounge for veriloga varactor code
you can modify to suit (or, find a varactor model you like and
just linearize or cal-map the C-V transfer function). If it's a
circuit driven variation you are looking for, and not just a
stepping of a variable.

 

[erikl]

HSPICE has a Voltage-Controlled Capacitor (VCCAP) model, s. the HSPICE® User Guide: Simulation and Analysis (search for VCCAP): View attachment hspice_simulation+analysis_user_guide.pdf

 

[admiral_v]

Do you want to vary by simulator variable, by circuit voltage,
or what?

I suggest you look at whether veriloga is supported by your
HSPICE version and if so, scrounge for veriloga varactor code
you can modify to suit (or, find a varactor model you like and
just linearize or cal-map the C-V transfer function). If it's a
circuit driven variation you are looking for, and not just a
stepping of a variable.

the capacitors in this circuit change by move (capacitive accelerometer ) and Unfortunately i have no information about veriloge
if I understand correctly , i can use veriloge in hspice? how??

- - - Updated - - -

I study a little about verilog model in hspice and find this for resistor model if you can write variable capacitor in verivlog i thank you verrrry much

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Code dot - [expand]
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*Title: Simple Verilog-A Resistor
.hdl resistor.va
.options post=1
X1 1 0 resistor r=1 
VS 1 0 1 
.dc VS 0 10 1
.end

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The va file:

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Code dot - [expand]
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// Simple resistor
 
`include "disciplines.vams"
 
module resistor(p,n);
parameter R=1.0 from (0:inf);
electrical p,n;
analog I(p,n) <+ V(p,n)/R;
endmodule

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I write thank you
hspice

 

[admiral_v]

i looking for same as this for variable capacitor for use in Hspice

 

[erikl]

I think this application note can help you: View attachment Modeling_Voltage-Variable_Capacitors.pdf

 

[admiral_v]

thx for your answer

In order to simulate the transient response of the readout
circuit, a pair of time-varying sensor capacitors are required.
A simple varactor model is implemented in Verilog-A which
produces a voltage-controlled capacitor. This model has four
terminals, where two terminals are the capacitor terminals, and
the other are the voltage input terminals. The Verilog-A model
is built upon the following equation:
C = C0 + CV Vin (4)
Q = CVC (5)
IC = dQ/dt (6)
This model consists of a fixed capacitor C0, and a variable
capacitor CV . The model takes in a voltage Vin as an input and
provides a variable capacitor C. Note that VC is the voltage
across the capacitor C. In this design, C0 is assumed to be
100 fF, CV is 1 fF, and Vin can be any time-varying voltage
signal that controls the change in the output capacitance
.




i dont know how define and write Vi and c=c0+c1vi equation in verilog-a and use it in hspice

 

[erikl]

Find here a thread which shows how to avoid a common error. And now let me g00gle this example for you (top PDF).

 

[admiral_v]

i find this verilog-a .va file
how write hspice netlist for this va file and define sine input .thx

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Code Verilog - [expand]
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`include "constants.vams"
`include "disciplines.vams"
 
module vccap(Cp, Cn, Vp, Vn);
 
    input Vp, Vn;
    inout Cp, Cn;
 
    electrical Cp, Cn, Vp, Vn;
 
    real C;
 
    parameter real C0 = 0;
    parameter real CS = 1;
 
    analog begin    
        C =c0+ CS * V(Vp,Vn);
        I(Cp,Cn) <+ C * ddt(V(Cp,Cn)); 
    end
 
endmodule

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