| 摘要 |
The sampling element comprises a DC sampling voltage source, a threshold sampling circuit and a photoconductive switching element. The threshold sampling circuit includes a signal-under-test input, a sampling pulse input and an IF signal output, and has a sampling threshold with respect to sampling pulses received at the sampling pulse input. The photoconductive switching element is connected between the DC sampling voltage source and the sampling pulse input of the threshold sampling circuit. The sampling device comprises a DC sampling voltage source, a threshold sampling circuit, a photoconductive switching element and a light source. The threshold sampling circuit includes a signal-under-test input, a sampling pulse input and an IF signal output, and has a sampling threshold with respect to sampling pulses received at the sampling pulse input. The photoconductive switching element is connected between the DC sampling voltage source and the sampling pulse input of the threshold sampling circuit. The light source is operable to generate optical pulses and is arranged to illuminate the photoconductive switching element with the optical pulses.
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