RF Noise of 65-nm MOSFETs in the Weak-to-Moderate-Inversion Region

Abstract

In this letter, the RF noise performance of 65-nm MOSFETs with 60-, 90-, 130-, and 240-nm drawn gate lengths has been extensively investigated in the weak-to-moderate-inversion region for low-power and low-voltage (LPLV) applications. Noise measurements show that although the noise performance is directly related to gate length ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Lg</i> ), it does not monotonically scale with the inverse of gate length. When biased in the weak-inversion region, a transistor with slightly relaxed gate length, instead of minimum gate length, will benefit from a smaller gate resistance and a smaller equivalent noise resistance <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Rn</i> . The transistor transconductance ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gm</i> ), output conductance ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gd</i> ), unity current gain frequency ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">fT</i> ) , maximum frequency of oscillation ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ), and noise parameters are extracted as a function of the drain current density and compared among devices with different gate lengths.