Other Parts Discussed in Thread: LMK00301
Tool/software:
Dear Sir or Madam,
input
I am driving the CLKin0 pin with a 50 ohm source 100 MHz sine signal. I have placed on R30 50 ohm and on C10 100nF. I have removed the 100 ohm R24. The CLKin0* is 50 ohm terminated. R28 and R22 are 100nF caps. So input is AC coupled.
output:
I am measuring SE on CLKouA0 (LVPECL configured) the absolute phase noise of the signal on a 50 ohm terminated PN instrument. The CLKoutA0* is 50 ohm terminated on the SMA connector. The output is pulled down to GND over 160 ohm + AC coupled over 100nF before the SMA connector (default eval board configuration)
The phase noise is at app. -120dBc/Hz white (unexpectedly bad). The output does not have a 50 % duty cycle. The input is a -170dBc/Hz source.
OK , I can imagine that by driving the input differentially and using both outputs for measurements over a diff to se block it would help. But even this (assuming 12dB gain or maybe 20dB) does not reach the expected <-160 dBc/Hz noise floor.
Any idea what I am doing wrong?
Best.
