Measured Voltage Waveforms Research Articles

A Fully-Automated Electron Beam Test System for VLSI Circuits

A fully automated, stroboscopic electrobeam test system that analyzes the behavior of logic VLSI circuits, this system consists of a stroboscopic electron-beam tester combined with an LSI CAD system. LSI circuit design data, read from the CAD system, provides a designed map. The host computer performs interconnection pattern recognition by superimposing this map onto an observed stroboscopic SEM image. Then, once the circuit nodes for voltage waveform measurements are automatically determined on the superimposed map. Next, the electron beam is positioned on the actual circuit-under-test wires. These automatic processes result in measured waveforms, which are displayed on the host computer terminal. This system has been applied to a 2.3K-gate logic LSI circuits, and has been successful in locating the critical path. This system, coupled with the recently developed fault diagnostic electron-beam tester, Finder, constitutes a unified electron-beam test system.

Pulsed plasma thruster ignitor plug ignition characteristics

The operating characteristics of the semiconductor spark gap ignitor plug used to initiate the discharge in a pulsed plasma thruster are investigated. Current and voltage waveform measurements for the ignitor plug alone, and for the plug mounted in the thruster cathode indicate an average dynamic impedance of 0.2 ohms for a wide range of operating conditions, and a trigger circuit energy transfer efficiency to the plug on the order of 25%. Two modes of trigger ignition are found which are related to the rise time of the applied voltage pulse. Analysis of plasma characteristics reveals plug erosion to occur primarily in the semiconductor and anode regions, by mechanisms including plug metal embrittlement, plasma sputtering and vaporization caused by the discharge current pulse. Measurements also indicate a plume velocity on the order of 1580,000 cm/sec which increases with trigger circuit stored energy. The results establish levels of performance for future applications of semiconductor spark gap ignitor plugs in plasma devices.

Effect of the measured voltage waveform on the readings of a diode peak voltmeter

1. The error in voltage measurement by means of diode voltmeters due to the distortion of the waveform can be several times greater at high frequencies than at low ones. 2. When voltages are measured at frequencies close to the value of: $$f = \frac{{f_p }}{n},$$ (9) there can be considerable additional resonance errors due to the presence of harmonics in the voltage under test. 3. In order to account for this error it is necessary to have quantitative and phase data on the harmonics in the signal under test, which are not always available. Hence, when measuring voltages by means of diode peak voltmeters, and especially when determining experimentally the resonance error characteristic of these voltmeters, it is advisable not to choose frequencies (if that is possible) close to the value given in Formula (9). The question of a compulsory indication of the resonance frequency in the technical specifications of voltmeters should be raised. 4. When the resonance error curve is determined experimentally it is advisable to set particularly high requirements for the auxiliary oscillator voltage waveform and to take steps to reduce the content of each harmonic (and especially those of a higher order) to 0.1 to 0.2%. 5. Diode voltmeters used in standard signal generators and power meters at frequencies for which the resonance error becomes important, can produce errors several times greater than the nonlinear distortion coefficient. This fact must be taken into consideration when standard signal generators are developed.