Schematic is similiar to EVAL Kit. Integer mode. Fref=10MHz. Loading sequence: REG 06h: frac_rstb=0; buff_rstb=0; REG 03h: intg; REG 09h: setting cp_UPcurrent_sel, cp_DNcurrent_sel; REG 0Bh: pfd_phase_sel=1. Incoming data verified by reading procedure. We made sure that the changing of the charge pump current thru REG 09h impacts the CP Output. But we don't see the locked VCO output, LD=0, VCO output signal is on the upper rail and CP output is about 200 mV (600 mV when CP current=0).
Could you share an idea what happens ?
Thanks in advance, Dmitry Kuznetsov, RF department of Moscow Radio Research Institute/