AMS - OpAmp Text Book Example Wont Quite Compile

[mixotricha]

iverilog version : 10.3 (stable)

// ------------------------------------------------------------------------------------------------------------------
// Operational Amplifier taken from https://m.eet.com/media/1171203/ms-part3.pdf
// ------------------------------------------------------------------------------------------------------------------

`include "disciplines.vams"

module ampl (
inp,
inm,
out,
vdd,
vss
);

input inp,inm,vdd,vss; output out;
electrical inp,inm,out,vdd,vss,N;
parameter real Gain=1k, // DC gain (V/V)
Vio=0, // input offset (V)
GBW=10M, // Gain-Bandwidth product (Hz)
Rdc=300, // DC output resistance (ohms)
Rac=100; // AC & Sat output resistance (ohms)
real Gm, Rres, Ccap, Vnom; // internal variables

// Macro for diode-like exponential dependence between voltage & current:
// Returns current of isat when voltage is zero, and decreases by
// a factor of 100 for each dV decrease of input voltage:
define fclip(V,isat,dV) isat * exp(4.6*(V)/(dV) ) analog begin @(initial_step) begin // constants computed at startup Rres = Rdc-Rac; // inner resistor value Gm = Gain/Rres; // input transconductance Ccap = 1 / (M_TWO_PI*GBW/Gm); // capacitor to get specifed GBW
end

// Contributions of current for each branch in the topology diagram:
I(N,vss) <+ -GmV(inp,inm); // transconductance from input
I(N,vss) <+ (V(N,vss)-V(vdd,vss)/2)/Rres; // resistor equation: I=V/R
I(N,vss) <+ ddt(CcapV(N,vss)); // capacitor equation: I=d(CV)/dT

// top & bottom parts of limiter
I(N,vss) <+ fclip(V(N,vdd),1,40m) - fclip(V(vss,N),1,40m);
I(N,out) <+ V(N,out) / Rac; // series resistance on output

end
endmodule
// -----------------------------------------------------------------------------------

from the shell : iverilog -gverilog-ams opamp.v

Something wrong in the syntax of this example or is the AMS support not up to this yet?

I see the disciplines.vams did get included and is part of my iverilog install.

[martinwhitaker]

I'm not familiar with Verilog AMS, but I know iverilog only supports a subset of the language.

[caryr]

Icarus does not currently support the contribution statement or the ddt() function. Cary On Wednesday, June 2, 2021, 1:33:00 PM PDT, martinwhitaker ***@***.***> wrote: I'm not familiar with Verilog AMS, but I know iverilog only supports a subset of the language. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or unsubscribe.