Sizing of Feedforward-Compensated High-Speed Operational Amplifiers

This paper studies no-capacitor feedforward (NCFF) compensation multiple-stage operational amplifiers which can achieve very high speed. However, achieving high unity gain frequency (UGF) requires meticulous pole-zero cancellation which is nontrivial to realize in practice. We develop in this paper a deterministic method combining gm/I
D
-based sampling and analytical design equation based constraints, a sizing method that is instrumental to realize ad hoc pole-zero allocation. Simulation has confirmed that the sized circuits can achieve substantially high UGF for the NCFF type amplifiers.