ANALOG_DE_GLITCH_CIRCUIT

Published:2009/6/19 5:13:00 Author:May | From:SeekIC

Low-frequency signals produced by transducers, measurement equipment, or data loggers often appear like the first waveform in the figure. The circuit shown operates as a tracking sample-hold, and the transients are replaced in the output by the stored value of the current signal at the instant of the transient. The input signal is buffered and inverted by ICla, and the differentiated result shown at 2 ap-plied to the inputs of two comparators IC2-a and IC?-b. VR1 and VR2 set levels to prevent false or unnecessary operation. Either comparator output triggers the mono IC3 from positive or negative signal transients. When IC3 has not been triggered, TRI and TR2 'p' channel JFETs are on, and IClb operateb as an integrator with a high leakage, and tracks the input signal. When the mono is trig-gered as at 3, TRI and TR2 turn off and the previous signal value is held constant, as shown at 4. The resulting output waveform can then be easily filtered to remove the harmonics from the restoring step at the end of the mono period, if needed. The criteria for successful operation are: t2 > t1 (mono period longer than glitch)t2/T small (to optimize output waveform) Signal bandwidth Signal phase The signal range is approximately ±5V, depending on the tfansient amplitude and polarity. The mono period shown is 100 mS, but this can be optimized in practical applications. The shorter the mono period in relation to the signal waveform, the better the quality of the result.



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