Channel length influence on the analog characteristics of asymmetric self-cascode association of SOI transistors

Abstract

This paper presents an experimental analysis of channel length influence on the analog characteristics of asymmetric self-cascode association of SOl transistors. It is shown that the increase of the drain current and transconductance is more pronounced with the reduction of the length of the transistor close to the source (L1), and, differently from the symmetric self casco de, suffers little influence of the length close to the drain (L2).On the contrary, the output conductance of symmetric and asymmetric threshold voltage structures is benefited by the increase of L2 and L/> although the asymmetric structure may offer a reduction of up to one order of magnitude in comparison to the symmetric one. It results in larger intrinsic voltage drain for asymmetric devices. This increase has shown to reach more than 20 dB for similar dimensions, or allow for dimension reduction without intrinsic gain degradation.

Effect of high temperature on analog parameters of Asymmetric Self-Cascode SOI nMOSFETs

“…It can be seen that the shorter the sum Ls + LD, the higher the current. Also, shorter Ls have much more impact on the rise of the current level than LD, related to the effective channel length reduction [3]. The same behavior with current levels can be noticed on Fig.…”

“…Recently a variation of the SC structure has been proposed, presenting reduced doping concentration at MD channel in order to effectively reduce the electric field near the drain, while keeping MS with standard doping to avoid threshold vo lt age (VT) lowering [3]. This structure has been called asymmetric SC (A SC) and is reported to provide better analog parameters than a The authors would like to thank CAPES, CNPq and FAPESP for the financial support.…”

Self-Cascode Current-Voltage Curve-Construction Algorithm from Single MOSFET Measurements for Analog Figures-of-Merit Extraction

“…The difference of the gain extracted from the code results and the reference reaches 2.5 dB on 49 dB maximum for the A-SC with L D =1 μm and of 3.2 dB on 62 dB maximum for the A-SC with L D =10 μm. The benefits on the g m , g D and A V that are observed for the A-SC that features a longer L D is related to the increase of the added resistance when the structure is operating in saturation [9]. This can be noticed when analyzing the intermediate node voltage (V X ) as a function of V GS for V DS of 1 V and 1.5 V, as presented in Fig.…”

“…16. The drop on V X that happens when increasing L D will affect the transcon- ductance and output conductance in a positive way, which is explained in detail in [9]. Still, it is important to notice that the algorithm is capable of following the trend of V X .…”

“…Previous studies have shown its benefits for analog circuit applications such as amplifiers and current mirrors [6], [8]. Design options concerning doping concentrations and channel length combinations have been studied in the references [9], [10]. Because of these advantages and analog circuit design potential, this work will focus on providing a coding method to facilitate its experimental electrical assessment.…”