Shady Ahmed
Member level 5
I am working on a 3rd order, 1 MHz Sigma Delta ADC with the following Specs
3 level quantizer and OSR = 32.
I am facing a linearity problem that i don't know how to fix it.
The system achieved max SQNR = 69 dB at Vin Full Scale and Max Frequency (i.e: Fin = Fb)
The following figure shows the PSD:
However, the simulation with Fin = F_bandwidth/3 ,, the max SQNR = 60.76 dB which means I am losing about 9 dB ..
and here is the PSD with the lower input frequency
I know that means that i have harmonics issue (2nd , 3rd ,, ) ,, How can I fix it ?
3 level quantizer and OSR = 32.
I am facing a linearity problem that i don't know how to fix it.
The system achieved max SQNR = 69 dB at Vin Full Scale and Max Frequency (i.e: Fin = Fb)
The following figure shows the PSD:
However, the simulation with Fin = F_bandwidth/3 ,, the max SQNR = 60.76 dB which means I am losing about 9 dB ..
and here is the PSD with the lower input frequency
I know that means that i have harmonics issue (2nd , 3rd ,, ) ,, How can I fix it ?