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--- r2r_dac [2012/04/18 11:11] – created wadmin
+++ r2r_dac [2020/09/17 18:56] (current) – old revision restored (2018/08/26 11:36) wadmin
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 == The simplest ==
 A 1 bit DAC can output only 0 or Vcc. Its accuracy is obviously poor (50% !) and its dynamic range is ... none !
+== Accuracy rule of thumb ==
+The deal for DAC accuracy is to consider that resistor accuracy shall be lower or equal to the dynamic quantum of the DAC. As soon as the accuracy of the resistor used in the R2R network is greater than the quantum expressed in percentage of the dynamic range, limit is exceeded.
+=== Using 5% accuracy resistors ===
+bit DAC can be achieved with 5% accuracy resistors. Dynamic range is 24dB.
+=== Using 1% accuracy resistors ===
+bit DAC can be achieved with 1% accuracy resistors. Dynamic range is 36 dB.
+=== Using 0.01% accuracy resistors ===
+bit DAC can be achieved with 0.01% accuracy resistors. Dynamic range is 78 dB.
+This explains why poor 16 bits DAC with an ENOB of 12 bits can achieve very clean quality sound if well filtered : with 78dB dynamic range, 13 bits DAC is good for audio replay.
+== The speech limit ==
+Generic speech dynamic range is 45dB from whisper to yelling. Meaning that for proper and clean voice transcription, theoritically, 8 bit is optimum because it leads to a 48dB Dynamic range.
+== Human Dynamic range limit ==
+The human ear full dynamic range is roughly 90dB : from low noise of a quiet night to loudness of standing in front of an aircraft engine :)
+This is achieved with 16 bits precision, which would require 0,001% precision resistors...