3 Summary

Combining two LMX2820 devices does improve phase noise performance. Performance improvement in section-B is about 1-dB. This is not much, but may be beneficial for critical systems. In section-C, the phase noise improvement is near the ideal 3-dB improvement. This is especially useful for communication systems where low spot phase noise at 1 MHz offsets and higher are critical for eliminating interference threats. The penalty of course is the need for two devices and thereby doubling the power consumption. The full feature set of the LMX2820 provides the ability to synthesize a wide frequency range and to adjust phase to ensure proper synchronized combining for this application.