A noise suppression circuit and a test circuit comprising the noise suppression circuit

Abstract

The invention provides a noise suppression circuit. the impedance is connected in parallel with the impedance from the floating system to the common-mode reference ground; wherein the two ends of theimpedance are a floating system reference ground and a common mode reference ground respectively, the noise suppression circuit comprises an inverted active band-pass filter, the impedance is connected between the two input ends of the inverted active band-pass filter, and the center frequency or the passband frequency of the inverted active band-pass filter is set as a known frequency point or frequency band of target noise and is used for carrying out inverted amplification processing on the target noise; and an impedance circuit is connected between an input end and an output end of the inverted active band-pass filter so as to attenuate the target noise. Due to the fact that the center frequency or the pass band frequency of the inverted active band-pass filter is arranged at the knownfrequency point or the frequency band of the target noise, the equivalent capacitance value of the inverted active band-pass filter at the frequency point or the frequency band of the target noise ismaximum, and the filtering effect on the target noise signal is the strongest. Correspondingly, the invention also provides a test circuit comprising the noise suppression circuit.

Description

technical field [0001] The invention relates to the technical field of circuit testing, in particular to a noise suppression circuit and a test circuit including the noise suppression circuit. Background technique [0002] In the field of semiconductor automated testing, precision small-signal testing is often accompanied by external noise interference, such as power frequency interference, which deteriorates the accuracy of test results and increases the dispersion. Especially the test of high-impedance line, such as small leakage test, the external noise interference is particularly serious. Therefore, in the above test applications, the suppression effect of test equipment such as floating systems on external noise often determines the test quality. [0003] When measuring a DC floating system, since the floating system (such as a floating VI source meter) relies on a high-frequency transformer to achieve floating, the parasitic parameters of the high-frequency transform...

AI Technical Summary

Problems solved by technology

It is not difficult to increase the resistance, but it is very difficult to reduce the capacitance small enough, because the parasitic capacitance of the space is always present and cannot be avoided

However, common mode noise is an AC component and is sensitive to capacitance, so it is very difficult to reduce impedance Z1 for common mode noise

[0013] In view of the limitations of the above-mentioned solution to directly reduce the target noise, a simpler and more direct solution is needed for semiconductor automated testing

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