Calculation of MOSFET distortion using the transconductance-to-current ratio (g<inf>m</inf>/I<inf>D</inf>)

Abstract

We present analytical expressions for MOSFET distortion as a function of inversion level, represented by g m /I D as a proxy. The expressions are particularly useful for moderate inversion, where the generic textbook equations fail. Unlike previous approaches, the method requires only a small number of technology parameters. For an estimation of g m nonlinearity, only the subthreshold slope is needed. Two additional parameters are required to model g ds nonlinearity. The derived expressions are validated based on SPICE simulations using a well-calibrated 65-nm PSP model set.

A Start-up Assisted Fully Differential Folded Cascode Opamp

“…Common-Centroid and inter-digitation techniques have been used in the layout to minimize the input referred offset. Differential-pair and cascode transistors sizes have been decided using gm/id methodology [13] and mismatch guidelines [15]. Table-II reveals that the present design is the only design which used start-up circuit to bring the circuit out of latch-up issue, whereas [4] also has no latch-up issue but it's power consumption is higher.…”

Using Modified Bessel Functions for Analysis of Nonlinear Effects in a MOS Transistor Operating in Moderate Inversion

“…In fact, we demonstrated this doing the calculations in the second part of Section VII. The necessity to return back to transistor model was realized also in [18] but the analysis used there was still a small-signal analysis. This integration of the proposed analysis with / mD gI design method is considered as a matter of the future work, and the first step which we are going to do in this direction is to obtain the expression for / out D DS g I V    (using the analogy between derivation of (3) from (2) and operating with the second term in Tsividis' model.…”

“…The model which allows one to connect the transistor bias and the regions of operation with calculation of harmonic distortions was absent. The / mD gI characteristic so successfully used in design of linear circuits [14,15] is not fully adapted for analysis of nonlinear distortions [16][17][18], because of the limitations occurring when Taylor series' are used for nonlinear circuit design (a good example is dependence of the 'sweet spot" on the signal strength overlooked in [12]). The Bessel functions used in this paper help to see better the effects when large amplitude sinusoidal signals are applied.…”

Charge-Based Distortion Analysis of Nanoscale MOSFETs

“…For these reasons, the analysis of the harmonic distortion in devices and building blocks has been a research topic for decades [10], [12]- [16]. In [10], Sansen carried out one of the first systematic distortion analysis on BJTs and MOSFETs in order to explain the origin of frequency spurs in telecommunication circuits.…”

“…They used the PSP model and measured devices and circuits in 90-nm node. In [16] Jespers and Murmann used the core long-channel equations of EKV model in order to express the first-, second-and thirdorder gate transconductances as a function of the normalized inversion charge and then of the transconductance efficiency G m I D . Moreover, they took into account also the nonlinearity introduced by G ds .…”