R2R FPGA

[JeD76]

Has anyone conducted experiments with R2R resistor values?

I would like to get a lower output impedance without compromising the sound.

I saw 7.5 and 15 kOhm on the Internet. I also found that there is no sound above 3 kOhm.

 

[jan.didden]

I don't think you will get a lot of replies.
It is very unclear what it is exactly what you have.
Schematic?

Jan

 

[JeD76]

Classic r2r circuit on FPGA with equalizing resistors of FPGA key resistance. No buffer required.

 

[lcsaszar]

R2R is a digital to analog converter in this context? What switching element do you use? I belive a high input impedance buffer is mandatory.

 

[JeD76]

R2R is a digital to analog converter in this context? What switching element do you use? I belive a high input impedance buffer is mandatory.

Yes. This is a DAC. I'll upload a photo now.

 

[JeD76]

 

[Mark Tillotson]

R2R is a digital to analog converter in this context? What switching element do you use? I belive a high input impedance buffer is mandatory.

Why buffer? Resistors are linear. So long as the switches have much lower resistance than the resistors you should be fine treating an R-2R network as its Thevenin equivalent, a plain resistive source of impedance R. Of course heavily loading the network will add attenuation, buffering prevents that.

 

[JeD76]

I level the resistance of the keys. With a resistance of R 1kOhm it is possible to achieve 0.006%