relation between settling time and UGB

[manissri]

what is 3db bandwidth and ugb

hi i am desinging an ota for pipelined adc of 12.5ns settling time .
what should the gain and UGB of this OTA.
what is the relation between settling time and UGB.
plz clearify me ..
waiting for ur reply ..
manish

 

[tyanata]

Settling time Ts=t*LN(1/e)

t - timeconstant

t=1/2*π*BW=Av/2*π*GBW= if PM≈70°

e - coefficient of settling the output signal in percents!

 

[manissri]

hi ur equation
t=1/2*n*BW
what is the n signifies..in above equation..
and t=Av/2*n*GBW
here what is A ( is it gain)
plz clearify it ..
manish

 

[tyanata]

Hi,

π-this is pi=3.14

Av- open loop gain.

 

[hebu]

Assuming this is first order system. The settling time is related to the 3dB Bandwidth. the time constant is 1/W3db. So, Ro*C is the time constant.
Once your OTA is used in feedback system, the settling time depends on the
feedback sturcture, β*ωt.

 

[ablue]

settling time is also reletated to feedback factor of your opamp if you dont use the opamp in unitgain buffer, you can also google some papers !!!