
Digital sampling oscilloscopes
is ON, it does not 'see' the output impedance of the integrating
memory.)
It is impossible to design a sampling gate with infinite attenuation
in the OFF state, and different ways have been developed of
dealing with this problem. In a simple two diode sampling gate,
such as that shown in Figure 9.9, the blow-by is too large to
ignore. In one model of digital storage oscilloscope, the blow-by
is measured- by acquiring a full scan's worth of data with the
sampling pulses absent and the sample gate therefore
permanently OFF ~ and the signal then acquired ...