Davood Fathi - Advanced VLSI Lab, School of ECE, Faculty of Eng., University of Tehran
Nasser Masoumi,

The active MOSFET mixer is one of the most important stages specially in the input of the communication systems. Thus the analysis of its output noise, has a great importance [1-3, 5-6]. In this respect, two main techniques, the mathematical [2, 3] and the physical approaches areused. With the technology progress, the need to increase the velocity and complexity of the integrated circuits, design of transistors with the size of less than 100 nm has been noticed by researchers. In this paper an accurate noise analysis for active mixers in nanoscale technologies, based on the variations of the two parameters W/L (transistor size) and fLO (local oscillator frequency) is presented. In this study, two important sections of an active mixer, the switching pair and the transconductor, are considered. In this middle, the transistor technology nodes 45, 65 and 90 nm which have been presented in PTM (Predictive Technology Model) [4], have been used in this research for the noise analysis in a mixer. For this purpose, the transconductor and the switching pair in a mixer have special importance [2, 3]. The noise variations of these two sections depend on various parameters such as the local oscillator amplitude and frequency, the bias current, etc. [2, 3, 5]. The effect of W/L on the mixer output noise is analyzed and noticed in this paper, whereas has been less noticed in the other studied references