Data Sheet

ADRF5715

APPLICATIONS INFORMATION

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Rev. 0 | 13 of 14

The RF transmission lines are designed using a coplanar wave-

guide (CPWG) model with a trace width of 16 mil and ground

clearance of 6 mil to have a characteristic impedance of 50 Ω.

For optimal RF and thermal grounding, as many through vias as

possible are arranged around transmission lines and under the

exposed pad of the package.

The RF input and output ports (ATTIN and ATTOUT) are connected

through 50 Ω transmission lines. On the VDD and VSS supply

traces, a 100 pF bypass capacitor filters high frequency noise.

Figure 20 shows the simplified application circuit for the ADRF5715.

Figure 20. Simplified Application Circuit

RECOMMENDATIONS FOR PCB DESIGN

The RF ports are matched to 50 Ω internally, and the pinout is

designed to mate a CPWG with a 50 Ω characteristic impedance on

the PCB. Figure 21 shows the referenced CPWG RF trace design

for an RF substrate with 12 mil thick Rogers RO4003 dielectric

material. The RF trace with a 16 mil width and a 6 mil clearance is

recommended for 2.2 mil finished copper thickness.

Figure 21. Example PCB Stackup

Figure 22 shows the routing of the RF traces, supply, and control

signals from the ADRF5715. The ground planes are connected with

as many filled through vias as allowed for optimal RF and thermal

performance. The primary thermal path for the device is the bottom

side.

Figure 22. PCB Routings

Figure 23 shows the recommended layout from the ATTIN and ATT-

OUT pins of the ADRF5715 to the 50 Ω CPWG on the referenced

stackup. PCB pads are drawn 1:1 to device pads. The ground pads

are drawn solder mask defined, and the signal pads are drawn as

pad defined. The RF trace from the PCB pad is extended with the

same width 2 mils and tapered with 90° angle. The paste mask is

also designed to match the pad without any aperture reduction. The

paste is divided into multiple openings for the paddle.

Figure 23. Recommended ATTIN Pin and ATTOUT Pin Transitions

For alternate PCB stackups with different dielectric thickness and

CPWG design, contact Analog Devices, Inc., Technical Support

Request for further recommendations.