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Weighting filters are used in audio S/N measurements. Basic shape of filter is inverse to human ear sensitivity characteristic. One of these shapes is A weighting filter (exists allso B, CCIF etc). Idea is to give more weight to frequency components at which ear is more sensitive. On web you can find a lot data about audio weighting filters.
using a ideal circuit (R,C,VCVS) to implement the a-weight filter.
However, if i want to measure the a-weight noise in ADC channel,
How to implement this?
To simulate weighting filter you must know it's transfer function or equivalent filter circuit. In attechement I put CCIR 468-3 filter circuit where must be added +12.2dB amplifier and weighting curves A and CCIR 468-3. Weighting curve A is usually used with consumer audio products while CCIR is meant for proffesional usage.
For A curve I do not have transfer function or equivalent circuit. I suppose, filter order and topology should be the same as for CCIR filter. You may try some iterative simulation to get close result but it is rather slow and inaccurate way.
Hi - I was looking for an A-weighting filter circuit. Google led me to this discussion first, then to the content at <http://www.epanorama.net/documents/audio/aweight.html> . I have simulated the circuit from that link in LTSpice and it seems close to the A-weight curve posted earlier in this discussion. Note the source & load impedance requirements.
Extending my last post, another circuit with a similar but slightly different response is available at
**broken link removed**
There is also a good discussion about A weighting. This circuit has a slightly different response shape from the last one I posted and linked. They should both be verified against the standard if you need accurate results.
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