LMX2595EVM: LMX2595Eval

Yogender,

OK. If you want to change from 935 to 960 MHz, you could use the VCO divider of 12, which means the VCO ramps 11220 to 11520, or a range of 300 MHz.

So for automatic ramping, here are the steps:


1. Set proper expctations about VCO calibration
If the VCO has to change more than a certain amount (call it Threshold) then it has to calibrate for a certain time (call it Caltime). During this time, there will be a disturbance in the ramp. After this, the ramp will resume where it left off.
calibration breaks are unacceptable, then this is a showstopper. Consider a device with external VCO, like the LMX2492

2. Set up the GUI in TICSPro
The TICSPro gui has some steps and gives some helpful feedback.

3. Set up Threshold and minimum cal time in the GUI

You can specify the Threshold and the VCO will automatically calibrate this often, but if you say something that is too much, then it will ignore your request and calibrate anyways. At this frequency, at worst case temperatures, you can ramp about 50 MHz down and 25 MHz up. So a pessimistic estimate would be to tell the VCO to calibrate every 20 MHz (Threshold=20). The calibration time might be on the order of 15 us, but it might vary, so set MinCalTime to 25 us and you get a ramp that goes in sputs of 20 MHz and calibrates for 25 us, then continues.

Note that TICSPro does not give conservative enough feedback on the calibration free range and minimum calibration time. It will not warn you in some cases when it should.

Regards,
Dean