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Altera_Forum
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16 years ago

CIC and FIR megacores

Dear Forum I have designed a narrowband LPF using matlab which comprises a 12 stage CIC decimating filter with a decimation rate of 495. This is followed by a 361 tap Compensating FIR. This co...
Altera_Forum's avatar
Altera_Forum
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16 years ago

Thanks FvM,

I kinda thought that was the case - what threw me was the fact that the matlab generated script (when one instantiates the CIC megacore) asks for the sampling rate BEFORE the CIC. This made me wonder if the compensation filter also compensates (i.e., interpolates) for the decimation as well as the passband droop... it is odd that given a compensation filter goes hand in hand with a CIC in many instances, why none of the Altera examples provide a project that concatenates a CIC with a FIR, other than in theoretical terms.

So given the CIC takes us into a different clock domain, does the OUT_VALID output signal from the CIC megacore become the CLK input signal for the (compensation) FIR megacore?

AND presumably I'd need to add an Interpolating CIC to get back to the 93.333MHz domain, yes?

Kind regards, Kurt