zyunknown said:
Thank you! Still two more questions:
1.How about the stability in low frequency? Should i consider the stability from DC to the high band?
Yes, the stability should be considered from DC to very high frequencies.
zyunknown said:
2. What kind of K value will be OK? I think it is not enough that K is just greater than 1, how about being greater than 1.05 or 1.1?
if the stability factor is equal to 1, in this case the system "may" oscillate with some load and source impedances (conditional stability). Under this circumtance, some fine tuning may help you...
But better case to prevent the stability factor approaching to unity and keep far it away as much as possible.
But another remark: Less than unity doesn't mean that the circuit will absolutely oscillate.But this is valid around k=1 zone..
But the stability less than much from unity, the circuit will potenatially be unstable...