I am designing two stage fully differential amplifier. Both stage are CMFB compensated. My problem is that after first stage only there is so much offset in output of first stage (because of mismatch) Second stage ouputs are going to vdd and ground.
Auto-zeroing, Choppering, negative feedback, area increasing. There are many solutions, post your system and/or your circuits and write down what you want exactly.
Auto-zeroing, Choppering, negative feedback, area increasing. There are many solutions, post your system and/or your circuits and write down what you want exactly.
How do you control the gain? Don't bother you if it is changing a lot? If you can use negative feedback you can hold constant the gain and your output wouldn't sit on the gnd or vdd. Isn't it an option, the feedback? Easier than auto-zeroing. You will need clock, choose a clock frequency, design switches and so on...
How do you control the gain? Don't bother you if it is changing a lot? If you can use negative feedback you can hold constant the gain and your output wouldn't sit on the gnd or vdd. Isn't it an option, the feedback? Easier than auto-zeroing. You will need clock, choose a clock frequency, design switches and so on...
Hi, this opamp is used in a fully differential switch capacitor circuit. In the sampling phase, the opamp is connected in unity negative feedback. So do you think this will solve my problem and output will not swing to vdd/ground when there is mismatch.
Yes, if the 2 stages are connected as a unity gain buffer I think mismatch only cause small offset, like n*1mV, but the output won't sit on the vdd or gnd. If you set higher gain the mismatch caused output offset can increase, but the output still shouldn't be 0 or vdd, depends on the closed loop gain. If it operates when the gain is unity you are ok.