Simulating kT/C noise in discrete-time delta-sigma

Hi, 

I am trying to get the transient noise of my switched-capacitor delta-sigma in VerilogA. The building blocks are all ideal except the switches, which are modelled as follows:

`timescale 1ns / 1ps
`include "disciplines.vams"

module sw(in, n, s);
parameter real ron = 10.0 from (0:inf); // on resistance (ohms)
parameter real roff = 100.0M from (ron:inf);// off resistance (ohms)
parameter real td = 0.0; // delay time (s)
parameter real tr = 20n; // rise time (on -> off) (s)
parameter real tf = 20n; // fall time (off -> on) (s)
input s;
logic s;
electrical in, n;
real reff;

analog begin
@(posedge s) reff = ron;
@(negedge s) reff = roff;
@(initial_step) reff = (s ? ron : roff);

V(in,p) <+ white_noise(4*`P_K*$temperature*reff,"thermal");
I(p, n) <+ V(p, n) / transition(reff, td, tr, tf);
end
endmodule

However, I am getting zero transient noise while simulating in transient mode. I have the feeling that the white_noise can only be seen in small-signal analysis and not in transient simulations? If so, how can I get the transient noise from these switches?

Thanks

Kind regards, 

Nicolas

PS: I actually need transient noise for my own purposes and not pnoise results...