Getting CS5381 Distortion down!
Posted 7th September 2015 at 11:35 AM by googlyone
On thinking over the sensitivity of the CS5381 to the drive and input filtering capacitor I decided to explore the capacitors further.
I was also interested to note that a number of manufacturers seem to recommend a range of different capacitor values here.
Purely because it was handy - i.e. right in front of me on the desk - I threw an extra 2nF capacitor across the differential input of the CS5381. Boom - the distortion dropped 6dB straight off.
I muttered a few choice profanities, which made me feel an awful lot better, then arbitrarily threw a 470pf NPO ceramic cap across that lot, just to be sure. Well given I was off doing such arbitrary things - why not?
On analysis, 5nF capacitance at 20kHz is about 1.5K Ohms (reactive) which is within the capability of the op amp to drive.
The results?
Which I found rather pleasing, as using the "default" 2n7, this ADC was one of the poorer units sitting on my desk.
I am rather hopeful that in these PCB's, this is major area in which this ADC needs to be managed to get good performance.
I was also interested to note that a number of manufacturers seem to recommend a range of different capacitor values here.
Purely because it was handy - i.e. right in front of me on the desk - I threw an extra 2nF capacitor across the differential input of the CS5381. Boom - the distortion dropped 6dB straight off.
I muttered a few choice profanities, which made me feel an awful lot better, then arbitrarily threw a 470pf NPO ceramic cap across that lot, just to be sure. Well given I was off doing such arbitrary things - why not?
On analysis, 5nF capacitance at 20kHz is about 1.5K Ohms (reactive) which is within the capability of the op amp to drive.
The results?
Which I found rather pleasing, as using the "default" 2n7, this ADC was one of the poorer units sitting on my desk.
I am rather hopeful that in these PCB's, this is major area in which this ADC needs to be managed to get good performance.
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