Other Parts Discussed in Thread: LMX2594
I am using LMX2594 EVM and Reference Pro module with TICSPRO software. While doing phase noise measurement of frequencies in the range 3.5GHz to 5.5GHz it is noticed that there is a reduction in value of 6dB from what is expected. I tried with the following settings ;
fOSC = 100MHz
FPD = 200MHz
N div = 40
fVCO = 8 GHz
Ch Div =2
RF out = 4 GHz
phase noise @ 10KHz offset from the carrier of 4GHz is -110dBc/Hz.
In LMX2594 datasheet page no:14 , it is given that the phase noise @10 KHz offset is -110.1dBc/Hz for fVCO of 8GHz. So the expected value of Phase noise at 10KHz offset is -116dBc/Hz for fVCO of 8GHz with channel divider of 2. But the measured value is -110dBc/Hz.
The phase noise measurement is done with R& S Spectrum Analyzer FSU 20Hz-8GHz.
Other observations are of the following;
fOSC= 100MHz : FPD= 200MHz : N Div =55 : RF out = 5.5 GHz : fVCO = 11 GHz : Ch Div = 2 : measured value of phase noise @ 10KHz offset = -107dBc/Hz but expected value is -113dBc/Hz.
fOSC= 100MHz : FPD= 200MHz : N Div =50 : RF out = 5 GHz : fVCO = 10 GHz : Ch Div = 2 : measured value of phase noise @ 10KHz offset = -109dBc/Hz but expected value is -115dBc/Hz.
fOSC= 100MHz : FPD= 200MHz : N Div =70 : RF out = 3.5 GHz : fVCO = 14 GHz : Ch Div = 4 : measured value of phase noise @ 10KHz offset = -111dBc/Hz but expected value is -117dBc/Hz.