SWRA640H December 2018 – May 2024 CC1310 , CC1312R , CC1314R10 , CC1350 , CC1352P , CC1352R , CC1354P10 , CC1354R10 , CC2620 , CC2630 , CC2640 , CC2640R2F , CC2640R2F-Q1 , CC2642R , CC2642R-Q1 , CC2650 , CC2652P , CC2652R , CC2652R7 , CC2652RB , CC2652RSIP , CC2674P10 , CC2674R10
The LC filter should be laid out so that crosstalk between the shunt components is minimized. Figure 4-4 shows three different layouts from worse to best. The advantage with the layout to the right is that the parasitic inductance in the PCB track (in black) between the shunt capacitor and the series inductor is in series with the inductor. In the middle figure, the parasitic inductance is in series with the shunt capacitor forming a series LC circuit. The placement of C12, L13, C13, L14, and C14 in Figure 4-2 shows good design practice.
If the design cannot use the reference design as-is (for example, use of a different component size) the filter balun will most likely have to be re-tuned. Simulate both the TI reference design and the custom design using an electromagnetic simulator. The two designs should have the same S21/S22.