Hi,
I am new to Verilog-A and saw the following model for a Diode in Cadence's AMS reference manual.

module diode (a, c) ;
inout a, c ;
electrical a, c ;
parameter real rs=0, is=1e-14, tf=0, cjo=0, phi=0.7 ;
parameter real kf=0, af=1, ef=1 ;
analog begin
I(a, c) <+ is*(limexp((V(a, c)-rs*I(a, a))/$vt) - 1);
I(a, c) <+ white_noise(2* `P_Q * I(a, c)) ;
I(a, c) <+ flicker_noise(kf*pow(abs(I(a, c)),af),ef);
end
endmodule

How to read and understand this line? "I(a, c) <+ white_noise(2* `P_Q * I(a, c)) ;"
I see I(a,c) is being used on both left and right side of the assignments.
Thank you for the help.
Regards,
Sai.

To avoid the confusion you had initially, I would have written the module as

id = is*(limexp((V(a, c)-rs*I(a, a))/$vt) - 1);
I(a, c) <+ id;
I(a, c) <+ white_noise(2* `P_Q * id) ;
I(a, c) <+ flicker_noise(kf*pow(abs(id),af),ef);