Grounding optimization techniques for controlling radiation and crosstalk in mixed signal PCBs

Analog, digital and RF signals are being widely used on single printed circuit boards (PCBs) for network communication, multimedia and wireless signal processing applications. Separate ground islands or segments are provided for analog, digital, and RF circuits to minimize ground noise coupling from high speed digital to sensitive analog or RF circuits. The noise level for digital cellular equipment should be as low as 0.3 /spl mu/V. Isolated or improperly interconnected ground islands often become high-frequency resonant circuits or patch antennas. This paper describes techniques or procedures for determining optimized grounding for high-frequency mixed signal single board PCBs for minimizing crosstalk and radiated emissions.