An all-inversion-region MOST design methodology applied to a ratioless differential LC-VCO

Abstract:
This paper presents a general optimization method- ology for analog blocks in RF applications, with CMOS nanome- ter technologies, based on the complete exploration of all-in- version regions of MOS transistor (MOST). The fundamental tool is the systematic use of the MOST gm/ID technique and the description of the real behavior of all devices by means of semi-empirical models. To exemplify this technique, the differen- tial ratioless cross-coupled LC-tank voltage controlled oscillator (LC-VCO) circuit is studied. The implemented design flow minimizes the LC-VCO phase noise considering the constraints of current consumption, output common-mode voltage and output amplitude. To verify the method, six LC-VCO were designed and validated by comparing them with the corresponding electrical simulations. Index Terms — Optimization, Low power, MOST all-inversion regions, Design Methodology, LC-VCOs, RF