關於two-stage-opa unit-gain bandwidth可以多小?

robin0338

新手發問
  M% U% k+ e4 Z7 Mtwo-stage-opa
3 g) U# |# C: V7 A如果已知訊號頻域為100hz~50k hz左右，那如果設計unit gain bandwidth到50Mega hz以上的話，

是否有點浪費? 而且功耗也會多一些?

7 ]* k, n) c# m" w3 w/ D  E* o' O% o是否應該設計到unit gain bandwidth =1Mega hz  
  A- I) _% K! L# C* h5 `* V
-3db frequence =10k hz

( j3 Z% T) G$ B3 {5 }& M但是 two-stage-opa 的gain似乎是有極限的，那這樣頻寬是否也會造成無法縮減到1Mega hz
7 n7 k5 ]& z. _1 `4 G$ D
& L: a* O6 r5 o" o想請問版上的高手  謝

tsay

bandwidth is based on the time constant.. if you have 50hz so the timing is 1/50, you can get the T. after that you can get the 3db bandwidth