"Our goal was to create a no-compromises DAC and digital crossover with 69-bit processing.
The DAC is configured as a an R-2R ladder. It is a 24-bit network although 0.01% resistors can
not easily give a resolution higher than 14 bits."
引用第29楼leonbernieni于2014-11-28 09:20发表的 :
先前关注过的某块Sign Magnitude的r-2r板,出示的FFT让人不太相信:
0.0063%=-84dB=14bitENOB and 0.37%=-49dB=8bitENOB=109dB of D-range
it is surprising performance with 0.05%=11bit resister, especially D-range!
后来看到有解释说,基础结构R2R的THD是绝对数值,就是说如果0dB信号有-90dB的THD,那么在-60dB时的性能就是-30dB;而Sign Magnitude的在0dB时如果是-90dB的THD,那么在-60dB信号上还是会有-90dB的THD,即THD是相对值。
这个我是相信的 Sign Magnitude本来就是BB提出过的技术
PCM1702 PCM1704都有用上:
the PCM1702 is an advanced sign magnitude architecture
that eliminates unwanted glitches and other nonlinearities around bipolar zero.