Sampling Gate Research Articles

Feedthrough Induced Distortions in Sampling Oscilloscopes and Their Compensation

When signals in the duration range from some tens of nanoseconds to some tens of microseconds are measured in detail with a sampling oscilloscope coupled to a fast time averaging system, severe shape distortions are usually observed one to two decades below the maximum amplitude. It is shown that these distortions are mainly due to capacitive feedthrough over the nonoperating sampling gate. The analysis of this phenomenon shows that the observed response is the sum of the input signal and of its weighted convolution by a slow response of microsecond duration. Feedthrough was decreased by up to two orders of magnitude by a minor change in the input circuit of the sampling gate, without affecting the intrinsic high speed of the oscilloscope response. The methods to optimize this compensation are described. Applications to the correct measurement of exponentially decreasing signals over more than three decades are shown.

Ultra-High-Speed Photoelectric Spectrometer Using an Image Converter as the Sampling Gate

Ultra-High-Speed Photoelectric Spectrometer Using an Image Converter as the Sampling Gate

Spatial Sampling for Fast Single Events

A method for observing non-recurrent events having short rise-time has been developed. Signals are sent to a transmission line where 50 sampling gates are tapped. A control pulse triggered by the incoming signal opens simultaneously all the linear gates. Successive tapping points are placed at 200 ps "distance" and the opening time of the gates is a little less. The full event is observed for a period of 10 ns and reproduced with 50 points. At present only 18 points are tapped.

High Stability ``Boxcar'' Integrator for Fast NMR Transients in Solids

An improved double channel electronic sampling integrator with digital output is described which is particularly suitable for enhancing signal-to-noise in pulsed NMR studies in solids where narrow sampling gate widths and long data memory are essential. The sampling gate widths are 1 μsec or less. The difference signal between the channel inputs is converted to digital form and stored in a standard counter which may be modified to add successive counts, thereby computing the mean numerically. Since there is no analog integration the system has a pulse response time of 1 μsec. The system is free of ion or grid current drift problems common to previous designs. Thermal drift is small. Details of the circuits and graphs of integrating performance are presented.

Further Analysis of an Integrated Switching and Multiplexing (ISAM) System

This paper is an extension of earlier analysis work relating to a new method of achieving frequency division multiplexing, capable of being effectively integrated with time division switching. The band shifting inherent in frequency division multiplexing and demultiplexing is achieved by placing a sampling gate between a baseband and a sideband filter. When this technique is combined with time division switching, the transmission path also includes the cases of transmission via a switch between sideband filters, that may or may not cover the same sideband region, and between baseband filters. Resonant transfer is incorporated for all cases. Only the case of resonant transfer between baseband filters has been considered in the past. In general, the basic transmission path under analysis is the one between sideband filters, where the term sideband is used in the sense to include baseband. This is logical, since the baseband may be considered to be an upper sideband around zero frequency. Such a basic transmission path is rigorously analyzed on the basis of certain ideal assumptions. The purpose is to provide further insight into the fundamental operation of this new modulation-demodulatian scheme.