SWRA824 October 2024 CC1120
The original design of the smoke detector application used the LM5166 and the frequency output spectrum was replicable as seen in Figure 5-3. When looking into the LM5166 requirements for functionality, it is stated that the regulator requires a certain amount of ripple output voltage to be stable. This poses a problem in the case of the CC1120 transceiver, as it is optimal to have little to no ripple output voltage for a clean frequency output on the antenna.
Based on the test results, an optimal choice of DC-DC regulation can be made in a system so that external filtering or additional regulation is not needed. As many factors can impact the output ripple voltage of the regulator, it can be beneficial to test the effects of a regulator's ripple on the emissions seen in the frequency spectrum of a system. In this case, the correct choice for this application is the LMR36510 as it produces the minimal amount of spurious emissions at the antenna.