Trade-off between channel length and mechanical stress in the Operational Transconductance Amplifier designed with SOI FinFET

Abstract

In this paper, the trade-off between transistor channel length and the presence (or not) of the uniaxially strained SOI FinFETs for designing Operational Trasconductance Amplifier (OTA) is studied. It is studied SOI FinFETs with channel length of 150 nm (where the uniaxially strain is more effective improving the transconductance - gm) and 900 nm (where the Early Voltage is higher, improving the ouput conductance - gD). Once that the intrinsic voltage gain is Av = gm/gD, the trade-off above is analyzed in OTA designing characteristics as Av, GBW (product gain bandwidth), PM (phase margin), and PD (power dissipation). Two strategies for designing were used: the same transistor efficiency gm/ID and the same bias conditions ISS. The general analysis shows that strained SOI FinFET with 150nm of channel length stands out in almost all electrical characteristics compared to 900 nm, once that in spite of the Early Voltage is lower for short devices, the channel strain improves the gm and besides the channel area is lower.