Because circuits do not Behave predictably at microwave frequencies, engineers must often tweak them to achieve better performance. Highfrequency circuit design tools have reduced the need for tweaking prototype circuits. Yet software tools for system-level analysis have not evolved as quickly, forcing designers to use spreadsheets to accomplish this task. As a result, engineers cannot account for the effects that will impact the system once it is deployed in the field. In a five-page white paper, AWR explains how its Visual System Simulator (VSS) software suite for the design and optimization of communications systems offers a suitable system-level solution.

The white paper notes that spreadsheets fail to fully exploit or calculate all of the system effects that determine a receiver's RF link quality including the cascaded noise figure and image noise. Typically, this noise source is incurred in the downconversion process, which produces a desired center signal from the difference between a mixer's local oscillator and the input frequencies. The center frequency also incurs a noise penalty from a higher-image frequency, which places a signal at the center frequency after downconversion.

Image noise can be reduced through filtering. If system-level analysis is performed solely with a spreadsheet, however, the effect of image noise cannot be calculated. To avoid such an imprecise solution, many engineers are starting to investigate the use of software tools. The white paper explains that the migration to VSS should be rather instinctive for them, as it uses office-productivity software like Microsoft Excel, while detailing the software's features and capabilities.

AWR, 1960 e. Grand ave., ste. 430, el segundo, ca 90245; (310) 726-3000, FaX: (310) 726-3005, internet: www.awrcorp.com.