hans_r
Newbie level 5
open loop amplifier gain monte carlo analysis
Hi,
I'm using a differential amplifier as a comparator to compare a ramp with an input voltage (ramp ADC principle). The comparator is just an amplifier with enough gain to amplify to Vdd/Gnd. I want to do Monte Carlo analysis to see how the gain changes caused by the mismatch. This is where I run in to a problem: the gain collapses in most of the monte carlo runs. I believe this is a simulation problem, not a circuit problem. Even when I use very big sizing (10's µm in 180nm process) the problem remains very big! I think it is because the DC bias point at the output changes (it drives the current mirror to other operating region), and therefore the gain-calculation is wrong: it appears to be very small. Offcourse the whole problem starts with the fact that I am using an amplifier in open-loop! Therefore I am looking for help on how to simulate it accurately!
Can someone tell me how to accurately do gain Monte Carlo analysis on a comparator?
Your help wil be much appreciated!
Kind regards.
Hi,
I'm using a differential amplifier as a comparator to compare a ramp with an input voltage (ramp ADC principle). The comparator is just an amplifier with enough gain to amplify to Vdd/Gnd. I want to do Monte Carlo analysis to see how the gain changes caused by the mismatch. This is where I run in to a problem: the gain collapses in most of the monte carlo runs. I believe this is a simulation problem, not a circuit problem. Even when I use very big sizing (10's µm in 180nm process) the problem remains very big! I think it is because the DC bias point at the output changes (it drives the current mirror to other operating region), and therefore the gain-calculation is wrong: it appears to be very small. Offcourse the whole problem starts with the fact that I am using an amplifier in open-loop! Therefore I am looking for help on how to simulate it accurately!
Can someone tell me how to accurately do gain Monte Carlo analysis on a comparator?
Your help wil be much appreciated!
Kind regards.
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