Hi,
@ buddypoor : Quote:1.) I suppose you donīt want a slope of -12dB/Okt. . Instead it should be only -6dB/Okt (equivalent to -20 dB/Dec).
I agree. Maybe analogrf was trying to convey this.
Quote:2.) Therefore, 60 dB is equivalent to 3 decades with -20 dB each.
That means: Unity gain frequency is three decades above 500MHz
I slightly Disagree on this point. This point seems to depend on where you start counting your decades from. 500MHz is the -3dB freq. where gain has already fallen down to 57dB.
Acc to how i would calculate the UGB, GBW product is constant. Gain at -3dB freq = A
DC / sqrt(2) . So UGB = 500MHz * 1000/sqrt(2).
Now this 353.xyz GHz UGB is not realizable.
Coming back to AnalogRF ,
Pls check your specs once again.
3dB Freq is mostly quoted for Filters. You Hardly quote -3dB freq. for an opamp / error amplifier as a spec. 3dB freq is mostly quoted for A CLOSED LOOP which is UGB in OPEN-LOOP. I am highly suspicious that 500MHz you are tryin to design is a CLOSED LOOP 3dB BW of some Loop, which will require you to design an opamp with 500MHz UGB.
Disclaimer :-- The above assumption is based on my CMOS exp. If you are talking about Si-Ge, that's a different matter altogether.
--
Mayank.