SBAA661
February 2025
LMX1205
1
Abstract
Trademarks
1
Flicker Noise, Noise Floor, and Total Noise
1.1
Flicker Noise
1.2
Noise Floor
1.3
Total Noise
2
Finding the Slew Rate
2.1
Finding the Slew Rate With an Oscilloscope
2.2
Calculating the Slew Rate From Power and Frequency
3
Impact of Slew Rate on Phase Noise
3.1
Modeling of Input Clock Slew Rate, Inherent Device Noise, and Output Jitter
3.2
Slew Rate Impact on Flicker Noise and Noise Floor
4
Application of Slew Rate Rules to PLL Synthesizers
4.1
PLL Flicker Noise
4.2
PLL Figure of Merit
4.3
Other Areas in PLLs Where Slew Rate has an Impact on Performance
4.4
Improving PLL Slew Rate for Better Performance
5
Application of Slew Rate Rules to Data Converters
6
Summary
7
References
Appendix A: Relating Slew Rate, Power, and Frequency
Appendix B: Relating Slew Rate, Frequency, Jitter, and Phase Noise
Appendix C: Equations for Data Converters
8.1
Relating Sampled Signal Slew Rate to SNR
8.2
Justification That SNR Decreases 1dB per 1dB With Input Power for Slew Rate Limited Case
Appendix D: Calculations for Data Converter Example
Application Note
Impact of Slew Rate on Noise