Effects of Forward Body Bias on High-Frequency Noise in 0.18-$\mu{\hbox{m}}$ CMOS Transistors

Abstract

In this paper, the effects of forward body bias (FBB) on high-frequency noise performance in deep-submicrometer CMOS transistors are presented. It was observed that noise parameters NF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> in both N and PMOS increased significantly under FBB. FBB may appear as a great concern in the low noise circuit design. This is in contrast with the improvement of other device parameters induced by FBB, such as reduction of threshold voltage ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> ), and increase in speed. The underlying physical mechanisms for the noise increase in N and PMOS were found to be different. In NMOS, high-frequency noise behavior can be well explained by a combinational effect between substrate resistance noise and nonequilibrium channel noise. However, increase of noise in PMOS was found to be mainly due to the substrate resistance noise. The contribution of nonequilibrium channel noise is trivial.