iamxo
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Hi guys, I want to test (not simulation) an OTA as is shown in the figure. This test method comes from one IEEE paper, but I have one big problem with this testing method, which is the offset of this OTA.
The OTA is a folded-cascode amplifier with gain-boosting which is to be used in the sample hold amplifier in ADCs. I want to test the basic parameter of the OTA (such as GBW, SR).
However, in the pcb testing, the common-mode output voltage is not the same as that in circuit simulation (1.5V). we get 3V and 1V at output (Vdd is 3.3v). And I find the offset causes the problem, which is verified in simulation after I add offset to the OTA ( but in designing this circuit, we did not simulate the whole test circuit with offset, this is a big fault).
And i can not find any relationship between offset and output voltage though i tried to analyze the circuit. Could someone help me? any suggestion will be helpful.
The OTA is a folded-cascode amplifier with gain-boosting which is to be used in the sample hold amplifier in ADCs. I want to test the basic parameter of the OTA (such as GBW, SR).
However, in the pcb testing, the common-mode output voltage is not the same as that in circuit simulation (1.5V). we get 3V and 1V at output (Vdd is 3.3v). And I find the offset causes the problem, which is verified in simulation after I add offset to the OTA ( but in designing this circuit, we did not simulate the whole test circuit with offset, this is a big fault).
And i can not find any relationship between offset and output voltage though i tried to analyze the circuit. Could someone help me? any suggestion will be helpful.