skyjam
Newbie level 5
I'm working on a PCB implemented first order CT Sigma Delta Modulator with very slow input signal <10Hz; 200KHz sampling frequency.
I have completed my board and got some results. Good news is that the board can work, but the SNR performance is only 45 dB...and my expected value is 100 dB...
I think the noisy external DAC reference and input signal are perhaps the reason to the bad SNR performance. So I want to ask you to recommend some suitable "machines" to do measurement task...
Here are some questions with details:
1. The input signal amplitude is very low, which is just around 40mV. Could you recommend the type of signal generator which can provide such low differential signal and enough precision? Or is there any ways to make the input signal "clean"?
2. The DAC reference signal is from a simple resistive divider, thus the precision of the supply to the divider is important. I used a DC power supply (Agilent E3631A) for the DAC reference but its noise amplitude is around 100mV with 5V voltage output. So could you recommend the type of DC supply served as clean DAC reference?
I have completed my board and got some results. Good news is that the board can work, but the SNR performance is only 45 dB...and my expected value is 100 dB...
I think the noisy external DAC reference and input signal are perhaps the reason to the bad SNR performance. So I want to ask you to recommend some suitable "machines" to do measurement task...
Here are some questions with details:
1. The input signal amplitude is very low, which is just around 40mV. Could you recommend the type of signal generator which can provide such low differential signal and enough precision? Or is there any ways to make the input signal "clean"?
2. The DAC reference signal is from a simple resistive divider, thus the precision of the supply to the divider is important. I used a DC power supply (Agilent E3631A) for the DAC reference but its noise amplitude is around 100mV with 5V voltage output. So could you recommend the type of DC supply served as clean DAC reference?
