Common mode electronic noise in differential circuits
Differential circuits are assumed to reject common-mode noise yet no parameter is available to describethat rejection as the Common Mode Rejection Ratio (CMRR) applies only to deterministic signals, not torandom noise. We propose a model and a method to analyze the contribution of the input common-m...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2019 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/174258 |
| Acceso en línea: | https://hdl.handle.net/2117/174258 https://dx.doi.org/10.1016/j.measurement.2019.04.028 |
| Access Level: | acceso abierto |
| Palabra clave: | Amplifiers (Electronics) Operational amplifiers Electronic noise Differential circuits Instrumentation amplifiers Cross-correlation Noise model Common-mode rejection ratio Soroll Electronic Amplificadors (Electrònica) Àrees temàtiques de la UPC::Enginyeria electrònica |
| Sumario: | Differential circuits are assumed to reject common-mode noise yet no parameter is available to describethat rejection as the Common Mode Rejection Ratio (CMRR) applies only to deterministic signals, not torandom noise. We propose a model and a method to analyze the contribution of the input common-modeelectronic noise to the output voltage noise of differential circuits. The analysis shows that the sameparameter-matching conditions that improve the CMRR determine common-mode noise rejection butCMRR is more sensitive to mismatching. For example, a low-frequency CMRR as low as 8 dB implies thatmore than 82% of common-mode noise is rejected. Thus, often only differential-mode noise is relevant.However, if the equivalent input current noise sources predominate over equivalent input voltage noisesources, cross-correlation between them partially yields common-mode noise that will also be rejected.We also propose a simple test that yields an estimate of that correlation. |
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