LTspice can model the ((electronics) noise your circuit. We are going to continue using the pre-amplifer circuit from the Electret Mic Breakout Board and run a noise analysis. But you get the idea, noise can be bad when it is unwanted. I'm sure an audio example would have been better to use here. A noisy op-amp circuit may skew that current reading and cause unwanted effects such as incorrect current readings on the microcontroller which keeps the battery from being over or under current. Charging cycles of rechargeable batteries as well the load current are very important parameters to monitor for the overall health of the battery and safety of the user. For example, a battery management system using op-amps to sense the current. Specifying the gain of a dependent source as a Laplace transform function is restricted in LTSpice to. Noise is most commonly concerning in op-amp circuit where precision is everything. A small-signal AC analysis is performed using the. The parameters/attributes is everything after that. If this happens to you, then try a right click and use option 'save link as' which should allow you to save the file complete. The schematic files are ASCII yexy and some browsers may display the file as lines of text. Noise analysis let you view the noise inherent in your system as well as injected noise from outside source when modeled properly. M2 is the name for the MOSFET below and its drain, gate, source and substrate is connected to nodes 3,2,0,0 respectively. The fileis called ACbasic1.asc It should open directly with LTspice.