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Double Sampling Method

IP.com Disclosure Number: IPCOM000036003D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Harder, CS: AUTHOR [+2]

Abstract

A double sampling method is described. It allows sampling of high speed signals without synchronization of the signal to the sampling pulse repetition rate. The principle is applicable to any sampling technique.

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Double Sampling Method

A double sampling method is described. It allows sampling of high speed signals without synchronization of the signal to the sampling pulse repetition rate. The principle is applicable to any sampling technique.

The method is based on a dual sampling measurement, as illustrated in the figure. The signal, applied to a dual sampling gate, is sampled twice using two sampling pulses (A, B) with a very well- defined delay between them. By processing the signals of the two sampling operations in a signal processor and displaying the resulting signal (Y) as a function of the delay (X) between the two sampling pulses, one can reconstruct the original signal without relying on the synchronization between signal repetition rate and sampling rate. Time jitter in the measurement is only given by the jitter between the two sampling pulses.

As shown in the figure, for some particular signals the signal processing can be very simple. For sine waves as well as short spikes, one only needs to add the signals of the two sampling operations, rectify the resulting signal, whereby the high frequency com ponents caused by the beat frequency between sampling rate and signal repetition rate are eliminated, filter-out unwanted components, and form an average signal. This average versus the delay between the two sampling pulses is then a replica of the original signal.

By using two sampling gates and applying two different signals, one can perform a measurement of r...