ADRF5025

Data Sheet

Rev. B | Page 12 of 13

PROBE MATRIX BOARD

The probe matrix board is a 4-layer board. Similar to the

evaluation board, this board also uses a 8 mil Rogers RO4003

dielectric. The outer copper layers are 0.5 oz (0.7 mil) copper

plated to 1.5 oz (2.2 mil). The RF transmission lines were

designed using a CPWG model with a width of 14 mil and

ground spacing of 7 mil to have a characteristic impedance of

50 Ω.

Figure 22 and Figure 23 show the cross section and top view of

the board, respectively. Measurements are made using GSG

probes at close proximity to the RFx pins. Unlike the evaluation

board, probing reduces reflections caused by mismatch arising

from connectors, cables, and board layout, resulting in a more

accurate measurement of the device performance.

0.5oz Cu (0.7mil)

RO4003

0.5oz Cu (0.7mil)

1.5oz Cu (2.2mil)

1.5oz Cu (2.2mil)

W = 14mil

G = 7mil

T = 2.2mil

H = 8mil

1.5oz Cu (2.2mil)

1.5oz Cu (2.2mil)

Figure 22. Probe Matrix Board (Cross Section View)

Figure 23. Probe Board Layout (Top View)

The probe matrix board includes a through reflect line (TRL)

calibration kit allowing board loss deembedding. The actual

board duplicates the same layout in matrix form to assemble

multiple devices at one time. All S parameters were measured

on this board.

Impedance Matching

Impedance matching at the RFx pins can improve the insertion

loss and return loss at high frequencies. Figure 24 and Figure 25

show the difference in the transmission lines at the RFC, RF1,

and RF2 pins. This same circuit is implemented on the probe

matrix boards and the evaluation boards.

The dimensions of the 50 Ω lines are 14 mil trace width and

7 mil gap. To implement this impedance matched circuit, a

5 mil trace with a width of 5 mils was inserted between the pin

pad and the 50 Ω trace. The calibration kit reference kit does

not include the 5 mil matching line, and therefore, the measured

insertion loss includes the losses of the matching circuit.

Figure 24. With Impedance Match

Figure 25. Without Impedance Match