A Modular Operational Amplifier Design

This paper proposes a module of a high gain and high swing 2-stage amplifier. It is suitable for building a general operational amplifier in a modular fashion with various optional performances. The proposed module alone offers opened-loop voltage gain up to 124 dB and GBW of 10 MHz without loading conditions. To assemble a 124 dB voltage gain operational amplifier with load driving capacity of Ω 50 // 10 pF , two modules must be cascaded as a 2stage buffered Op-amp. In this manner, the module can be effectively utilized as either gain or buffer stage. Generally, the module can deal with resistive load in the range Ω Ω k 1 ~ 50 and capacitive load in the range pF pF 10 ~ 1 with unconditional stability. The idea is confirmed by simulation results on Spectre from Cadence with 0.6μm CMOS from AMS, and supply voltage of 3.3V.