Is there any setting that will reduce the spurious emissions on the si4713 chip? Does the si4710/11 have less spurious? Right now I'm measuring about -30-35dbc +-3MHz from carrier. Is there any way to improve it?
Where is the spurious coming from: is it the DSP or PLL? I'm curious why it produces these signals.
Maybe there is another chip I could use? I don't want to build whole PLL, VCO, DSP system myself. It's too complex and the component count is very high.
No, there's no software settings that can reduce the spurious emissions. As you can see from the data sheet, the Transmit Emissions is -30dBc max. You observation is correct. Si4710/11 is also at this level. It seems there's no effective way to improve it since it's the in-band spurious.
It comes from the harmonics of the IF inside the chip.