This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Part Number: LMX2594
the issue if the LMX2594 has a noise floor of -236dBc/Hz has been raised once before. The answer from TI and the datasheet itself proving the -236dBc value is not clear though.
The noise floor value in question of -236dBc/Hz is proven only from the Figure 14 - "Calculation of PLL Noise Metrics" in the datasheet. However, the noise floor itself is not shown in the measurement trace in this Figure at all! What is shown is the 1/f noise and not the flat phase noise region. You may draw the red line as an indication of the flat region, but this red line without the measurement data trace is misleading.
Calculating the true noise floor of the part LMX2594 can be done from the several phase noise measurements in the datasheet, the eval board and other LMX2594-related gizmos (i.e. TIDA-01346, Multiple PLL Combination Reference Design).
Calculating the PLL noise floors and therefore FOMs from the Figures 3, 4, 5, 6, 7 and 9 (hopefully TI used Wenzel 100MHz OCXO for these figures) using the 20LOG(N) and 10LOG(Fpd) reveals the realistic value of -228dBc/Hz, 8dB worse than the specified value of -236dBc:
Fig. 3: Flat noise floor at 100kHz offset: -107.5dBc/Hz - 20*LOG(15000/200) - 10*LOG(200e6) = -228.0dBc/Hz!
Please clarify the issue or the possible miscalculation.
Thanks and best regards,
We are glad that we were able to resolve this issue, and will now proceed to close this thread.
If you have further questions related to this thread, you may click "Ask a related question" below. The newly created question will be automatically linked to this question.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.