I am using the ADF4159 with a divide-by-16 Prescaler VCO , and I am unable to configure the unit to get basic functionality, i.e. sawtooth chirp. The VCO is a combined TX and RX and has some similar characteristics to the ADF5901 VCO:
E.g. Tuning voltage = 0.7 to 2.5V
VCO sensitivity = 720 MHz/V
Are there some specific settings I am overlooking for the ADF4159 to work with a lower frequency prescaler?
My current setup utilizes a reference clock of 30 MHz and I have tried many values of f_PFD including, 15 MHz, 30 MHz, and 60 MHz without success.
For instance, are two example outputs from my ADC that is digitizing the down-converted time wave, i.e. the beat and doppler frequencies:
1. Parameters for first attachment: f_PFD = 15 MHz, pll_DEV = 6.246 MHz (rf_DEV = 100 MHz), t_chirp = 5 ms, f_adc = 50 KS/s.
2. Parameters for second attachment: f_PFD = 15 MHz, pll_DEV = 6.246 MHz (rf_DEV = 100 MHz), t_chirp = 5 ms, f_adc = 100 KS/s.
Any insight would be appreciated.