I would like to simulate a VCO with a certain bandwidth to account for signal attenuation at higher modulation frequencies.
Thus, I replaced the idtmod() function with the following: phase= 2PI(laplace_nd(freq,{1},{0 ,1}) % 1 - 0.5). This works fine but when
wanting to implement 1/(1+s/bw), where bw is the 3-db frequency,  the simulator takes for ever to simulate. Furthermore, when using 1/(1+s) the 3dB bandwidth should be 1rad/sec but the modulation signal passes through un-attenuated. It should all be straight forward but I must be doing something wrong.

Thanks for any feedback.

Then again, the difference between 1/s and 1/(1+s) is (nearly) absent for high frequencies, so that wouldn't explain why your signal passes through unattenuated -- assuming s>>1.