Effect of noise on analog circuit testing

Abstract

The effect of test environment noise (tester noise) on test waveforms is considered. Methods such as retrofitting of analog test equipment or performing multiple fast Fourier transforms (FFTs) on measured waveforms for repeatability and noise suppression are costly. We propose a simulation environment in which the tester noise characteristics along with wide-band measurement can be used to grade environment test waveforms and recommend noise-robust test waveforms. We use time averaged second order statistics such as the power spectrum density (PSD) and root mean square (RMS) values to characterize any noise considered. We then determine circuit primary output (PO) noise characteristics and use them to make decisions about the test waveforms and recommend more noise-robust tests. Results of experiments on an instrumentation amplifier, biquadratic filter and a Gilbert multiplier are presented.