A phase‐shift technique for high‐speed e‐beam testing with picosecond time resolution
ABSTRACT Electron beam sampling of high speed digital devices requires a high time resolution. At the same time, long-range phase shifting is necessary because signals in these circuits may have very long period lengths. In this article, a new phase-shift method is described which allows sampling of low repetition rate signals without any degradation of the time resolution. This long range phase shift is realized by an additional set of blanking plates or blanking capacitor, which, acting as a gate, selects one of a large number of electron pulses produced by a first blanking capacitor. This technique also allows fast switching between different phase angles. The phase-shift method was evaluated experimentally using the picosecond e-beam tester which was developed here. The time resolution of this tester has been optimized recently to allow for stroboscopic testing with a 7 ps pulse width at 20 mV/√Hz noise voltage and 0.5 μm spot size. This allows for the measuring of rise times down to 14 ps with an error below 10%. Phase shifts of 100 ns were realized without any degradation of this time resolution. Propagation delays of 3.5 ps could be resolved. Signal rise times of 40 ps, corresponding to 0.04% of the total delay could be easily measured.
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ABSTRACT: The aim of this paper is to point out the limits of the electron beam testability of MMIC given by the transit time effect (TTE). Theoretical investigations concerning the still open questions in connection with the electron beam testability of MMIC are thoroughly discussed. The calculations are based on the assumption of quasi-transverse electro-magnetic-waves which propagate as the fundamental mode on the MMIC typical waveguides, the microstrip lines and the coplanar waveguides. A criterion indicating the testability of a MMIC is defined. The microstrip line and the symmetric coplanar wave guide with different dimensions are examined. In addition, strategies for the reduction of the TTE, i.e. for the improvement of the electron beam testability of MMIC are proposed.Microelectronic Engineering 05/1990; DOI:10.1016/0167-9317(90)90043-S · 1.34 Impact Factor