High bandwidth low power operational amplifier design and compensation techniques

Slew-rate enhancement and trojan state avoiding for fully-differential operational amplifier

“…If the transconductance is infinitely large, then the LHP zero can be completely removed and there are only two poles. However, this cannot be true in a practical case; [17] gives a detailed analysis of this topology. The drawback of this topology is that very large extra quiescent current is required to draw on additional common-gate stage transistors M6 and M7 for achieving large transconductance g mc .…”

“…Matching is critical in analog circuit design, and op-amps require particularly high matching performance for achieving small input-referred offset and high common-mode rejection ratio. Such transistor matching is mainly dependent on transistor size, transistor shape, and transistor orientation [17]. Transistors with large gate areas generally have better matching performance than those with small gate area, because as WL increases, localized random variation can be averaged out more effectively.…”

“…The feedback network is realized by indirect compensation that includes compensation capacitor C c and a transconductance stage g mc . The indirect compensation scheme removes the RHP zero in conventional Miller compensation by blocking high-frequency feed-forward small-signal current.As mentioned in[17], there are three possible topologies for achieving indirect compensation for a fully-differential two-stage amplifier. The first one is indirect compensation using additional common-stage stage, while the second is indirect compensation using cascoded loads and indirect compensation using cascoded input differential pairs.…”