Please help me: How to get a short settling time

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careking

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I have designed an OTA(gain booster),but the settling time of this OTA is too long(about 350ns). Who can tell me how to low the settling time.
Thanks!

Added after 34 minutes:

oh, no people help me^^
 

make sure it has no doublet and try to enlarge OTA's UGB. Also please refer Klass bult's classic paper
 

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    careking

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Increase current in your OTA, use minimum L, most important make sure no doublet in your frequency response UGF of your booster amplifier < 2nd pole of your total amplifier in closed loop configuration
 

Hello:

How do we tell if the major delay is due to the auxilary gain boosting amplifier or not?
 

Can you plot your step response.
 

The settling time of the circuit depends on the following:

1. The feedback factor
2. Load Conditions
3. Doublets: Should be avoided
4. Slew Rate

Based on first two points, you need to detemine the required GBW of the OTA. The slew rate can be decided based on the load conditions.

Regarding the effect of Gain Boosting Amplifiers on the overall settling time, you need to make sure that the poles contributed by the gain boosting loop are father away from the GBW of the overall OTA. This will ensure no inteference from the gain-boosting amps.

I hope the above information would be of some help.
 

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    careking

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Thank all very much
 

to get very less settling time
1.incese slew rate
2.decrease capacitance.if load capacitance is fixed..try to work with small transistor sizes..but it will decrease curr. so increase over drives.
 

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