Very practical design of high frequency PCB circuits
The choice of PCB plates must balance the design requirements with the availability and cost. Design requirements include electrical and mechanical components of the two parts. This material problem is important when designing a very high speed PCB board (greater than the frequency of GHz).
For example, now commonly used FR-4 material, in a few GHz frequency medium loss (dielectric loss) will have a great impact on signal attenuation, may not be applicable. For electrical purposes, it is important to note whether dielectric constant (dielectric, constant) and dielectric loss are applicable at the designed frequency.
2, how to avoid high frequency interference?
The basic idea of avoiding high frequency interference is to minimize the interference of high frequency signal electromagnetic fields, which is called crosstalk (Crosstalk). The distance between the high speed signal and the analog signal can be pulled up, or the ground guard/shunt traces is added beside the analog signal. Also pay attention to the noise jamming to the analog ground digitally.