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

robin0338

新手發問
two-stage-opa
: v2 u5 z& S- c8 g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，
# c: y; D: t/ j& e. W; |2 h* {
5 _7 G' [7 F6 E. R是否有點浪費? 而且功耗也會多一些?
& U% r7 y% H$ }9 D% I1 G; A+ \
是否應該設計到unit gain bandwidth =1Mega hz  

' c# E, i9 S+ q5 I7 M& K-3db frequence =10k hz
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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

- ?) S9 v0 v; g" @2 e" E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