THD of sigma delta ADC, strange results of simulation

[chrisccq]

thd delta

hi all. I meet a problem in my project and want to get your help. thks! the THD of the adc is about 100dB at the system level. but the simulation results show that the THD of the adc is about 72dB with the actual circuit. what's the main cause?

 

[safwatonline]

THD of sigma delta ADC

Maybe
1-wrong system level specs
2-wrong testbench
3-wrong behaviour models
4-error source not taken into account

 

[northeast1]

Re: THD of sigma delta ADC

hi all. I meet a problem in my project and want to get your help. thks! the THD of the adc is about 100dB at the system level. but the simulation results show that the THD of the adc is about 72dB with the actual circuit. what's the main cause?

the system level is ok, but the circuit design has some problem, such as op design.