Hi,
For two separate parts of a RF system, I need to generate a frequency ramp from 1.2GHz to 2.5GHz in 10ms, and another ramp from 6.5GHz to 6.8GHz in 10ms.
According to the datasheet of the LMX2594 and other treads in the forum, these ramps can't be made without VCO calibration.
Our circuit driven by the 1.2GHz to 2.5GHz ramp does not tolerate frequency jumps of more than 10MHz, otherwise, it cannot track the frequency and unlocks.
The circuit driven by the ramp from 6.5GHz to 6.8GHz can tolerate frequency jumps of less than 100MHz.
I made preliminary tests with an ADF5356 and the control software provided by Analog Devices. with this device, each VCO calibration selects the first VCO core (lowest frequency), then sequentially selects the next VCO core until the desired frequency band is reached, then switches the VCO capacitors until the exact frequency is reached. This results in large frequency hops than our system cannot handle.
Does the LMX2594 work the same way during calibration? If not, is there a way to generate ramps with frequency changes smaller than 10MHz between each step, even by reducing ramp rate if necessary and without an external VCO?
Thank you very much!
