Part Number: LMX2594
Other Parts Discussed in Thread: LMX2592
Hello Team
I come back with LMX2594. For phase conservation reason, I prefer to use integer or mash modulator with integer relation between Fosc=32 Mhz=F_PFD and Fout=7744Mhz. I try to have a spectrum without spurious, except F_PFD and harmonics.
In integer mode, I see some spurious at 100Hz. I confirm with spectrum analyzer looking Fout and also mixing output with Lab generator at the same frequency. See pulse at 100 Hz on oscilloscope. I know that internal architecture is more complicated that a simple N integer PLL. Could you confirm that we can not have simple integer behavior even in ‘’integer mode’’. See associated tcs file
I change mash ordre to 3..4. It removes 100Hz spurious, but I see spurious at +- 45Khz. I see also effect with other spurious and ICP value 3 ,6 ,9 ,12mA but not 15mA. I will be interested to have the best configuration for lower spurious. I don’t optimize the loop filter yet: we will use a low Fc (about 50khz).
The LMX2592 have other behavior about spurious (VCO is *2 for 7744Mhz output). I choose the LMX2594 because 7744 MHz output is available with internal VCO without multiplication (better phase noise). May be you have a better IC suggestion for my requirements: no spurious close to the carrier, phase conservation after on, off (integer value with 32 MHz).
