Design Methodology for Ultra Low-Power Analog Circuits using Next Generation BSIM 6 Compact Model

The design of analog circuits strongly relies on the accuracy of the models available in the circuit simulators. The recently proposed BSIM6 bulk MOSFET compact model is set to replace the hitherto widely used BSIM3 and BSIM4 models as the de-facto industrial standard. Unlike its predecessors which were threshold voltage based, the BSIM6 core is charge-based and thus physically continuous at all levels of inversion and from linear region to saturation region. Hence, it lends itself conveniently for the use of a design methodology suited for low-power analog circuit design and based on the inversion coefficient (IC). The IC based design methodology that has been extensively used in conjugation with the EKV model allows to make simple calculations of, for example, transconductance efficiency, gain bandwidth product, input-referred noise, mismatch offsets etc. This methodology helps to make a near-optimal selection of transistor dimensions and operating points even in moderate and weak inversion regions. This paper will discuss the IC based design methodology and its application to the next generation BSIM6 compact MOSFET model.