A new analogue circuit design methodology using independently optimised self-cascode (SC) structures is proposed. Based on the concept of the dual-workfunction-gate structures, which are equivalent to SC structures, transconductance and output resistance optimised SC MOSFETs were used in the differential input and output stages, respectively. An operational amplifier (opamp) with the proposed design methodology using standard 0.18 µm CMOS technology was designed to provide better performance. The measured DC gain of the fabricated opamp with independently-optimised SC MOSFETs was approximately 12 dB higher than that of the conventional opamp.

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