Are you questioning about using the Ramp source in your transient style circuit simulation? You have had exactly this same problem before but then it was the PulseRF source:
Again...
This Ramp source is from the Signal Processing (DSP) components in ADS, Timed library. It is intended for use within the ADS Ptolemy domain (the clue is the big arrow on the symbol) that can include Circuit Envelope Simulations and certain Transient/Convolution Simulations for modulated signal simulations. However, it will never work for regular circuit level simulations like S-parameter, AC, Harmonic Balance and regular Transient Time Domain (Spice like) simulations.
You are obviously finding these sorts of components and trying to use them when they are not a valid selection for the level of simulation you are performing. It would be best if you remove this choice entirely from your design environment. Go to the ADS main window when you have this workspace open and select the command - Design Kits > Manage Libraries... In the following window 1. Find the entry for dsp.defs. 2. Remove that library so that it is no longer referenced when this workspace is opened. This will reduce the choice of libraries/palette entries so that only those libraries relevant for circuit simulation, analog_rf, are presented.
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Similarly, when you create a new workspace make sure that the dsp,defs library entry in NOT selected.