Broadband sampling oscilloscope characterization with the “nose-to-nose” calibration procedure: a theoretical analysis

In the past the “nose-to-nose” calibration procedure has been introduced as probably the most accurate method to determine the impulse response of broadband sampling oscilloscopes like the HP54124T (bandwidth exceeding 50 GHz). The method is based on the hypothesis that “sampler kick-out equals oscilloscope impulse response”. This hypothesis was originally based on an intuitive approach and was later on verified experimentally as well as with SPICE simulations. Until now however there was no generalized mathematical evidence supporting this basic hypothesis. In this paper a mathematical theory is developed, which starts from a generalized sampler equivalent scheme, and which shows that, under conditions which are valid in practice, the sampler kick-out indeed equals the sampler impulse response