A compact model for flicker noise in MOS transistors for analog circuit design

Abstract

Designers need accurate models to estimate 1/f noise in MOS transistors as a function of their size, bias point, and technology. Conventional models present limitations; they usually do not consistently represent the series-parallel associations of transistors and may not provide adequate results for all the operating regions, particularly moderate inversion. In this brief, we present a consistent, physics-based, one-equation-all-regions model for flicker noise developed with the aid of a one-equation-all-regions dc model of the MOS transistor.

A compact model of MOSFET mismatch for circuit design

“…This approach along with the description of the ACM dc model resulted in a compact easy-to-use formula for mismatch that covers all operating regions. The results we obtained for mismatch are closely related to those derived in [25] for noise, since the physical mechanisms at the origin of both phenomena are similar. We conclude from our model that fluctuations in lumped parameters such as the threshold voltage are not appropriate for describing mismatch owing to the nonlinear distribution of carriers along the transistor channel.…”

“…Finally, using (11) and integrating (10) from source to drain results in (12) The result in (12) is essentially the same as that derived for flicker noise in MOS transistors in [25]. This is because mismatch behaves as a "dc noise" and the physical origin of both matching and noise is related to fluctuations in either fixed charges or localized states along the channel.…”

“…The other specificity of the ACM model is the use of the unified charge control model (UCCM) [24], which links the carrier charge density to the applied voltages according to (4) where is the pinch-off voltage, and is the channel potential at position . As shown in [25], the use of (3) in conjunction with (4) gives (5) Consequently, the ACM model is fully consistent with the quasi-Fermi potential formulation for the drain current [23]. As will be shown next, (5) is essential for finding the relationship between current fluctuation and carrier fluctuation.…”

“…On the other hand, if is low (linear region), then . Using the relationship between inversion charge density and current [21], [22], , and (13), (12) can be rewritten as (14) where we define as in [25], [28] …”

Figure‐of‐Merit‐Based Area‐Constrained Design of Differential Amplifiers

“…Therefore, here only flicker noise has been considered to introduce the concept developed. There exist numerous models for flicker noise in the MOS transistor [2][3][4][5][6][7][8][9][10]. In accordance with the most popular model [10], the flicker noise due to a MOS transistor can be lumped as a voltage source at the gate and is given by…”