When I am trying to run ac simulation and add a signal of the input, it said that cannot find the frequency vector

So I am trying to run a simulation of a AFE I have designed. The AFE is a part of sheet of the whole schematic file. What I did is to enter the AFE.sch and click on “simulation workbook” -> “settings”, and select the range of AC from 10HZ to 10MHZ. By adding the signal of the channel OSC1, it said “cannot find the frequency vector”. Not only the OSC1, any signal cannot be found to generate the simulation.

The AFE is like this

It might be useful that you start with a simple amplifier, just to check if dc and ac operations are working properly.

For ac simulation you will need a reference input voltage source. All other node voltages are then evaluated relative to this reference.

I am not sure if your AC source from your schematic does fulfill these requirements.

So instead place a voltage source VDC from symbol lib Simulation_SPICE onto your sheet, rename it (optional) to VAC, annotate it, and set its value to dc 0 ac 1 . So the reference is ‘1’, which is reasonable (divide all measured ac voltages by 1). You may choose another value, it does not matter, because the circuit is linearized anyway. Just the reference denominator changes. The dc value may be changed to establish the operating point (point chosen for linearization).

See picture attached:

Indeed such an AC source is missing in the symbol lib.

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