Understanding and correctly predicting cellular, radar, or satellite RF link performance early in the design cycle has become a key element in product success. The requirements of today’s complex, high performance wireless devices are driving designers to assess critical measurements—noise figure (NF), 1dB gain compression (P1dB), third order intermodulation distortion versus output power (IM3dBc), and signal-to-noise ratio (SNR)—long before manufacturing begins. Traditional modeling methods such as rules of thumb and spreadsheet calculations (Friis equations) give limited insight on the full performance of an RF link in next-generation wireless products. This white paper highlights the advantages of using specialized RF system simulation software to accurately predict critical metrics for wireless RF links.
Figure 1: Traditional use of the spreadsheet as a system tool.
Simulation Software—A Novel Approach
Traditionally designers have used spreadsheets (Figure 1) to do calculations such as cascaded noise figure, P1db, compression point, and/or third order intercept point of an RF link. The advantages of using a spreadsheet are two-fold: data entry is simple and spreadsheet software is readily available. As wireless devices become more and more pervasive and complex, the limitations of spreadsheets become more apparent. In other words, spreadsheet responses are based on standard equations and therefore do not typically account for mismatch between components or noise at image frequency. In addition, spreadsheets do not normally support data files such as S2p, spur tables, etc., nor do they support yield analysis or optimization—techniques that are becoming increasingly important in order to produce high performance devices at a competitive price.
