about the test of 8bit DAC, its snr is 55dB!

[williamy]

this DAC is current-steering, in test, the SNR of DAC in one aspect (sample and signal frequency is changed) exceed 50dB, but the SNR of ideal 8bit DAC is 50.
is it normal? or the test is wrong?

 

[Davood Amerion]

the 8 bit dac has 1/256 quantizing noise. so maximum signla to noise ratio will be
S/N max = 20 log 1 / (1/256) = 48dB
this means that S/N ratio at 8 bit DAC never exeed 48dB.

 

[renwl]

can you say something about your test environment?

 

[williamy]

About test environment: FPGA supply 14-bit digital signal---DAC process--return the output of DAC under test to FPGA, ADC in FPGA(12bit-ADI)output, then, FPGA collect the digital signal, using matlab, process it.

 

[williamy]

according the SNR formula, the SNR of 8-bit DAC or ADC is not bigger than 6.02*8+1.7. this formula should give the best SNR in ideal