What's an SCF filter in this AKM D/A chip?

[semente]

What's the SCF filter in this AKM D/A chip, what does it do?

Is it analogue or digital?

 

Thanks

 

[semente]

Found the answer

 

 

[bogi]

54 minutes ago, semente said:

What's the SCF filter in this AKM D/A chip, what does it do?

Is it analogue or digital?

 

It seems to be Switched Capacitor Filter and it is the D/A conversion stage itself. All processing before SCF is performed yet in digital domain - it is a digital signal preparation (digital volume control in DATT module, oversampling stage called here as De-Emphasis & Interpolator, delta sigma modulation) to be suitable for the D/A conversion low pass filter named here as SCF.

[opus101]

A switched capacitor filter is a kind of active filter where instead of using resistors and capacitors, the filter is made out of capacitors and switched capacitors take the place of resistors. There are a couple of advantages of this - in an IC, resistors normally can't be made to precise values but capacitors fare better in the precision stakes. The main advantage though is a switched capacitor is like a clock frequency controlled resistor. Which means filters can be made with variable cut-off frequencies, controlled by the frequency of the clock fed to them.

[Superdad]

On 10/21/2021 at 4:55 AM, opus101 said:

The main advantage though is a switched capacitor is like a clock frequency controlled resistor. Which means filters can be made with variable cut-off frequencies, controlled by the frequency of the clock fed to them.

 

Your whole post is the best explanation I have seen on the rationale behind SCFs. Thank you!