Multi-pulse sampling of signals using electrostatic force sampling

摘要

A method and an apparatus for providing non-contact measurement of waveforms proximate to a surface of a sample. In one embodiment, the described apparatus includes a composite probe waveform generator configured to provide a composite probe waveform having a plurality of overlapping component probe waveforms. Each of the overlapping component probe waveforms have a repetition rate substantially equal to the repetition rate of the sample waveform to be measured from the sample. The apparatus includes a cantilever with a signal path to carry the composite probe waveform to a position above the sample surface where the sample waveform is to be measured. In one embodiment, each of the component probe waveforms of the composite probe waveform is modulated at a frequency near a mechanical resonance frequency of the cantilever. Capacitive coupling between the cantilever and the signal line of the sample results in a periodic motion of the cantilever at a rate determined by the modulation frequencies of the component probe waveforms. By detecting the motion of the cantilever, and sorting out the excitation from the different overlapping component probe waveforms, the sample waveform can be determined.