Rf And Data Port Transmission Line Layout - Analog Devices ADRV9001 User Manual

Reference Manual ADRV9001
PRINTED CIRCUIT BOARD LAYOUT RECOMMENDATIONS
Figure 258. ADRV9001 AuxADC, SPI, Analog GPIO/AuxDAC, MCS±, and Digital GPIO Signal Routing Guidelines

RF AND DATA PORT TRANSMISSION LINE LAYOUT

RF Line Design Summary
The RF line design is a compromise among many variables. Line impedance, line-to-line coupling, and physical size represent the parameters
subject to compromise. Smallest physical size is in direct opposition to the ZCM of the line, which is directly opposed to the line EMI
performance. In addition, the interface between the RF line width and the device ball pad diameter on the PCB represents a potential
discontinuity. As the RF line width approaches the ball pad diameter, the risk associated with potential interface discontinuity reduces.
Balanced lines for differential mode signaling used between the device and the RF balun should be as short as possible. The length
of the single-ended transmission lines for RF signals should also be as short as possible. Keeping signal paths as short as possible
reduces susceptibility to undesired signal coupling and the effects of parasitic capacitance, inductance, and loss on the transfer function of
the transmission line and impedance matching network system. The routing of these signal paths is the most critical factor in optimizing
performance and, therefore, route these prior to any other signals and maintain the highest priority in the PCB layout process.
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