Si5351: I2C programmable clock generator / RF output spectrum

24/02/2015

1) U3S/Si5351 RF output spectrum on 28.126 MHz 

Spectrum on antenna’s connector.

Ref_Si5351XTAL27M_28M_10M

Fig.1.  Si5351A/Reference — XTAL 27 MHz (G0UPL Synth 5351A board)

Ref_Ext27M0_28M_10M

Fig.2.  Si5351A/Reference — External signal 27 MHz

Ref_Ext25M0_28M_10M

Fig.3.  Si5351A/Reference — External signal 25 MHz

Ref_Ext24M0_28M_10M

Fig.4.  Si5351A/Reference — External signal 24 MHz

Ref_Ext10M0_28M_10M

Fig.5.  Si5351A/Reference — External signal 10 MHz

Ref_Ext30M72_28M_10M

Fig.6.  Si5351A/Reference — External signal 30.72 MHz

Ref_GPSDO30M72_28M_10M

Fig.7.  Si5351A/Reference — GPSDO 30.72 MHz from u-blox LEA-M8F

2) U3S/Si5351 RF output spectrum on 144.490 MHz

Spectrum on antenna’s connector.

Ref_Si5351XTAL27M_144M_10M

Fig.8.  Si5351A/Reference — XTAL 27 MHz (G0UPL Synth 5351A board)

Ref_Ext27M0_144M_10M

Fig.9.  Si5351A/Reference — External signal 27 MHz

Ref_Ext25M0_144M_10M

Fig.10.  Si5351A/Reference — External signal 25 MHz

Ref_Ext24M0_144M_10M

Fig.11.  Si5351A/Reference — External signal 24 MHz

Ref_Ext10M0_144M_10M

Fig.12.  Si5351A/Reference — External signal 10 MHz

Ref_Ext30M72_144M_10M

Fig.13.  Si5351A/Reference — External signal 30.72 MHz

Ref_GPSDO30M72_144M_10M

Fig.14.  Si5351A/Reference — GPSDO 30.72 MHz from u-blox LEA-M8F

Notes:

  • 20 dB attenuator installed between U3S and spectrum analyzer
  • External reference source — Anritsu MG3681 signal generator
  • External reference signal power is +5 dBm which equal of the 30.72 MHz signal power from u-blox LEA-M8F

3) Si5351 RF output spectrum on 144.490 MHz (updated on 10 March 2015)

Spectrum directly from IC Si5351A (pin 10 — CLK0) with a standard 27 MHz clock (xtal) at 144 MHz for different spans.

Please note that 10 dB attenuator has been installed between pin 10 of Si5351A and spectrum analyzer.

Pin10_Si5351XTAL27M_144M_10M

Fig.15.  Spectrum at 144.490 MHz and span 10 MHz from pin10 Si5351A
Reference — 27.000 MHz xtal

Pin10_Si5351XTAL27M_144M_25M

Fig.16.  Spectrum at 144.490 MHz and span 25 MHz from pin10 Si5351A
Reference — 27.000 MHz xtal

Pin10_Si5351XTAL27M_144M_50M

Fig.17.  Spectrum at 144.490 MHz and span 50 MHz from pin10 Si5351A
Reference — 27.000 MHz xtal

Pin10_Si5351XTAL27M_144M_100MFig.18.  Spectrum at 144.490 MHz and span 100 MHz from pin10 Si5351A
Reference — 27.000 MHz xtal

 

4) Si5351 RF output spectrum on 144.490 MHz with an external reference 32 MHz (updated on 10 March 2015)

Spectrum directly from IC Si5351A (pin 10 — CLK0) with an external reference signal 32 MHz  at 144 MHz for different spans.

Please note that 10 dB attenuator has been installed between pin 10 of Si5351A and spectrum analyzer.

Out_Pin10_Si5351_ExtRef32M5dBm_144M_10M

Fig.19.  Spectrum at 144.490 MHz and span 10 MHz from pin10 Si5351A
Reference — external 32.000 MHz / +5dBm

Out_Pin10_Si5351_ExtRef32M5dBm_144M_150K

Fig.20.  Spectrum at 144.490 MHz and span 150 kHz from pin10 Si5351A
Reference — external 32.000 MHz / +5dBm

Out_Pin10_Si5351_ExtRef32M5dBm_144M_25K_PN

Fig.21.  Spectrum at 144.490 MHz and span 25 kHz from pin10 Si5351A
Reference — external 32.000 MHz / +5dBm
Phase noise -110 dBc/Hz @ 10 kHz

Notes:

  • 10 dB attenuator installed between Si5351A output (pin 10 — CLK0) and spectrum analyzer
  • External reference source — Anritsu MG3681 signal generator
  • External reference signal power is +5 dBm

Karen, RA3APW