Link budget analysis for multistandard receiver architectures

As devices shrink, creating integrated circuits (ICs) that work with the required accuracy becomes more difficult due to issues related to device physics. Receivers are part of an area referred to as "mixed-signal design," meaning that both analog and digital circuitry will be on the same IC. This too presents many challenging issues, as the analog circuitry is highly sensitive to disruptions caused by the noisy digital circuitry. Therefore, accurate modeling and simulation is crucial in the design of wireless receivers to ensure the best possible operation of the fabricated IC. Through simulation and modeling a designer can determine if receiver architecture will meet the required specifications and pinpoint the possible problems before valuable time is spent developing the actual circuit. This article will present design issues for multistandard wireless receivers to give the reader an understanding of the challenges involved in link-budget analysis. TITAN (Toolbox for Integrated Transceiver Analysis), a link-budget analysis tool developed at The Ohio State University Analog VLSI Laboratory, will be presented as an example of a tool for receiver simulation. To determine design performance, various requirements must be translated to model parameters. Among the requirements for receivers are noise floor (NF), second- and third-order distortion (IP2 and IP3, respectively), reciprocal mixing, and phase noise. TITAN offers a graphical interface and encapsulated models to the designer, eliminating the possibility of formula corruption. The interface provides a more intuitive and sophisticated way of setting up the simulation and provides the designer with more readable results. Additionally, a blocking profile component allows the architecture to be tested across multiple standards.