SNAA366 October   2022 LMX1204

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Basic Clock Distribution System
    2. 1.2 Pre-multiplier Stage
  4. 2Low-Frequency Reference
    1. 2.1 Pre-multiplier Stage
    2. 2.2 LMX1204 Multiplier Stage
    3. 2.3 LMX1204 Multiplier vs RF Synthesizer
  5. 3Real-World Application With AFE7950 RF Sampling Transceiver
    1. 3.1 AFE7950 Clocking Measurement Setup
    2. 3.2 AFE7950 Clocking Measurement Results
  6. 4Conclusion

2.1 Pre-multiplier Stage

Figure 2-2 shows a block diagram of the 3 × pre-multiplier stage using the TRF37C75 amplifier. Figure 2-3 compares the phase-noise performance of the pre-multiplier stage with that of the signal generator. Table 2-2 reports the integrated jitter performance for each configuration.

Figure 2-2 3 × Pre-multiplier Stage
GUID-20220906-SS0I-TLCR-RKQD-VC9HVFBGJTV8-low.png Figure 2-3 Phase-Noise Comparison of 1474.56-MHz Signal

As expected, the SMA100B provides the best output at 1474.56 MHz. The 3 × multiplied Wenzel oscillator performance is also quite good. The sweep of the SMA100B is nearly identical to the ideal response when the input performance is degraded by 20 × log (n), where n = 3 as the multiplication factor. As before, the multiplied-up Wenzel approach is significantly better than the Agilent PSG.

Table 2-2 Integrated RMS Jitter at 1474.56 MHz
Frequency Source RMS Jitter
1474.56 MHz R&S SMA100B 8.1 fs
Wenzel Oscillator - 3 × 22.2 fs
Agilent PSG 35.4 fs