Optoelectronic techniques for improved high speed electrical risetime

The NPL optoelectronic system for calibrating high-bandwidth sampling oscilloscopes is described, with emphasis on the importance of accurately defining the impulse response to enable the calibration of fast electrical pulse generators (risetime <15 ps). The problems encountered in determining the waveforms of such pulse generators, particularly aberrations close to the transition and long-term settling, are discussed and a proposal for the application of electro-optic sampling to the measurement of electrical pulse generators is presented.