16b capacitor SAR ADC test result anayse

[jerryzhao]

I think the root cause of this jump voltage and hystersis is the threshold voltage shift and hysteresis. Detail see the us patent5235333, 5675340, 5006853.
And the paper, T.L.Tewksbury "Characterization, Modeling, and Miniminzation of Transient Threshold Voltage Shift in MOSFET's" IEEE Jssc, MAR. 1994 .
T.L.Tewksbury "The Effects of Oxide Traps on the Large-Signal Transient Response of Analog MOS Circuits" Apr. 1989.IEEE JSSC.

 

[sankudey]

Hey! Is this solved? It wil be interesting to know the updates.

I had a small comment. Was there any digital calibration in place before and after the codes where between the coupling cap (series cap) appears? Any mismatch or top-plate to top-plate paracitics around the Cc (which can potentialy change the value of the Cc from its calculated value) will definitely lead you this kind of jump. If you write a simple MATLAB code just modeling the Cc and vary the Cc to check it; it will show that.

Any way; updates will be interesting to know.

sankudey

 

[zhixin]

I measurement many time, always see the hysteresis, I know the parasitic cap of couping cap, will lead a jump voltage, in my old design(12bit) ADC I see this effect. but that jump voltage is at the LSB section to MSB section node, not at the 1/2vr, 1/4vr etc. that jump without hysteresis.

I have the same problem that the jump voltage is at the LSB section to MSB section node.I do not know how to settle it.Can you tell me the way to solve it?