Tool/software:
As shown in Figure 1,
connect the output of the OCXO（Oven Controlled Crystal Oscillator） to the CLK-IN pin of LMK1C1108.
The 3.3V power supply is normal, and the Pin2 pin (1G) of LMK1C1108 is supplied with a high level.
The clock signal output by the OCXO is measured with an oscilloscope as shown in Figure 2 (pk-pk value is about 2.8V),
but there is no signal on the 8 output pins Y0-Y7 of LMK1C1108 measured with an oscilloscope.
What is the reason?
Thanks!
Hi Jie,
The output of the OCXO does look a little odd to me.
One more thing, in the picture I see a ton of clutter - can you ensure the IC is mounted properly and all connections are good? I am worried about the Clkin line and the VDD pins.
What is your ref clk slew rate? Minimum slew rate requirement is 0.1V/ns
Regards,
Vicente
Hi Jie, +
One more thing, this device requires external biasing.
Biasing for Clkin should be VDD/2.
Remember VOH_min is 0.7 * VDD and VOL_max = 0.3 * VDD
Refer to the EVM user guide. 
Slew rate always has an impact because if your slew rate is too low, the device outputs' phase noise will be impacted and you will most likely see distortion.
Regards,
Vicente
Hello!
I replaced the OCXO (10MHz) and resolved the issue. Now, the output of the OCXO is a normal square wave, as shown in Figure 1（pk-pk3.25V）:
I connected the output of OCXO to pin CLKIN of LMK1C1108 and measured with an oscilloscope that Y0-Y7 had no output.
Then, I added external biasing according to the circuit diagram in the EVM user guide. After adding external biasing, I measured the waveform of the CLKIN pin with an oscilloscope as shown in Figure 2(pk-pk2.13V, DC 1V):
But when measuring Y0-Y7 with an oscilloscope, there was still no output. I replaced it with another LMK1C1108, and the result was still the same.
Do you suggest any other potential causes?
Thanks！
Thanks for your reply!.
The output of OCXO is a square wave with pk-pk of 3.3V, as shown above.
I have tried both biased and unbiased methods, but LMK1C1108 did not output.
The output technical specifications of OCXO are as follows:
All circuit connections have been checked and pin 2 (1G) has been set to high level.
Do you suggest any othe causes?
Thanks！
