I am trying to produce 150 to 200 Mhz clock out of ADF4351 rfouta with no success.
Refin = 25 Mhz.
Attached the code for the registers and the schematic.
The differential clock inputs (CLK+, CLK-) specifications of the AD9613 require a signal between 0.3 and 3.6 Vpeak-to-peak (page 6). So your signal looks good.
What does 'no success' mean? Is there any signal from the RF output? Does the current drawn change when you toggle the powerdown bit (R2)? Does the chip respond when you program the various muxout modes (use an oscilloscope to monitor the muxout pin)?
Include a schematic , R184 , R166 ,R168 are removed.
I have found 2 problems .
1. The 3V3_CLK was not good . Now it is fixed.
2. The VHDL code that produces the CLK4351,DATA4351,LE451 was shifted by one bit . It is now fixed.
Still There is no output on RFOUTA+- pins.
Dialing the following registers.
1. Register 5 , 0x580005 .
2. Register 4 , 0xcff03c .
3. Register 3 , 0x2004e42 .
4. Register 2 , 0x808011 .
5. Register 1 , 0x200000.
If I configure Register 2 , Muxout as
1. Digital lock detect - The led is on.
2. Analog lock detect - The led is off .
3. DGND - The led is off.
4. DVDD - The led is on.
5. R divider output - The led is on. There is an output of 65Mhz.
6. N divider output - The led is on. There is an output of 47Mhz.
It looks like the chip is working / responsive , Yet I can’t get a output on RFOUTA +- pins.
What should be the level on RFOUTA + – , when the register 4 – RF Output Power is set to +5 dbm ? .
On C185 there is a sinus of 3 MHz @ 0.5 V ptp ,.
I am quite sure that the values of C185,C186,R183,R182,C187,R185 are not set for the range of 150 to 200 MHz.
How are you looking at the RF output? Do you have a spectrum analyzer?
Are all power supply pins at the correct voltage (check with multimeter)?
Can you disconnect the resistors and any load on the RF output and see if that affects anything?
I am back , I changed L1,L2 to 0.33uH , Change the output clock to 150 MHz.
Now I have a clock.
This clock is fed to a clock distribution ADCLK948 ( See attached PDF ).
The outputs on any Qx , !Qx are only 45 mV .
Resistors R188,R192,R195,...R209 are not installed.
Also R190,C209 are not installed.
I did as requested , R200,R190 = 0R , C209 = 6.8pF.
R712,R173,R179,R180 are 100 ohm, The output swings around 1.65V
Now if I dial for 60Mhz , I get a sinus of 106 mv at junction of the resistors and 200mv
at the output of ADCLK948
For 100 Mhz the outpus are 64 mv,116mv.
For 125 Mhz the outputs are 40mv,68mv.
Choosing Muxout for Analog lock
No matter what combination is used , I can't get the Analog lock to be on, Only Digital lock.
The outputs of the ADCLK948 are fed into AD9613 .
What is the minimum clock swing for the AD9613 to work ?.
Analog Lock Detect requires external components (see AN873). I recommend using Digital Lock Detect.
I will check with the ADCLK948 engineer and get back to you.
In the previous answer, I pointed out R172/R179 and R173/R180 set a bias at 1.65 V (which is at low side of 1.5 V~3.2 V in the datasheet), but I missed a suggestion “to remove R172/R179 and R173/R180”, and to tie Pin3 and Pin4 together with a small capacitor to GND to set bias for CLKIN0.
C209 bypass 6.8 pF as mentioned may be too small. Suggest a 1000 pF cap.
Double-check ADF4351’s output at nodes of Pin12/Pin13 (of ADF4351) to make sure normal swing, and double-check the swing at nodes of Pin1/Pin2 of ADCLK948 to make sure normal swing.
C209 is 1nF.
The outputs at both nodes are 480mV P2P.
This output is fed to AD9613 , Is it good enough ?.
I had recently designed my own adf4351 board using analog devices eval board schematic.All connections are given as per schematic only pin 23 is grounded but still lock is seen at 2470 MHz.After checking the schematic i had removed the ground across pin 23(Vcom) again i verified whether lock is seen or not.But now there is no lock and the voltage seen across this pin when ground is removed is half the tuning voltage.
Why is lock is not seen when pin no 23 is not grounded?
Why lock is seen when pin no 3 is grounded.?
What happens if Vcom is permanently grounded?
sorry above pin no 3 is wrong it is pin no 23
The part may lock with pin 23 grounded, but it will likely damage the part over time. You need to follow the datasheet specification.
sir, i am testing our own 4351 board which was earlier locked and now there is no LD output seen. I thought to test different modes using MUXOUT.I had programmed MUXOUT to VDD, GND, R DIV,.. ETC.I can see variations at MUXOUT. when i program to digital lock detect mode, MUXOUT=3.3v seen.As per analog schematic i placed 100ohm near it no voltage drop is seen across MUXOUT why? Device is working properly and all outputs are good to my concern.please help me.
I don't understand the problem. You said the device is working properly and all outputs are good.
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