benbiles
Member level 4
I am using some electrolytic 10uF capacitors to hopefully filter DC bias that exists between an ADC and a digitally controlled preamp chip.
PREAMP -> ADC INPUT
The preamp, TI pga2500 sergests using capacitors to decouple the preamp output from the ADC.
The output of the preamp and input of preamp is differential and I have used basic resistor attenuation to match the voltage
swing so the preamp is within the ADC limits..
I'm using Nichicon B1237 6.3V 10uF capacitors. one on each side of the differential audio path with the positive lead attached to
the preamps +1.8v bias.
The AC audio voltage swing is +/-2.4v peek ( not RMS )
There is also +0.9V bias on the ADC side of the differential.
My question is , does anyone know in this case if its essential to have bi-polar capacitors to take out the DC component from both sides?
should I use 2 capacitors back to back with positive leads connected to each bias signal PRE & ADC ?
there's a lot out there on the audiophile forums but I'm more interested in the actual theory of the DC decoupling in this case.
I would like the audio signals to swing around 0V at the point these signals connect together and not use a buffer as recommended by the preamp
datasheet.
Should I also add the bias voltage together with the AC voltage swing to calculate the capacitor rating required ? or in this case the 6.3V is enough?
PREAMP -> ADC INPUT
The preamp, TI pga2500 sergests using capacitors to decouple the preamp output from the ADC.
The output of the preamp and input of preamp is differential and I have used basic resistor attenuation to match the voltage
swing so the preamp is within the ADC limits..
I'm using Nichicon B1237 6.3V 10uF capacitors. one on each side of the differential audio path with the positive lead attached to
the preamps +1.8v bias.
The AC audio voltage swing is +/-2.4v peek ( not RMS )
There is also +0.9V bias on the ADC side of the differential.
My question is , does anyone know in this case if its essential to have bi-polar capacitors to take out the DC component from both sides?
should I use 2 capacitors back to back with positive leads connected to each bias signal PRE & ADC ?
there's a lot out there on the audiophile forums but I'm more interested in the actual theory of the DC decoupling in this case.
I would like the audio signals to swing around 0V at the point these signals connect together and not use a buffer as recommended by the preamp
datasheet.
Should I also add the bias voltage together with the AC voltage swing to calculate the capacitor rating required ? or in this case the 6.3V is enough?