My customer are designing PLL circuit with HMC698LP5 (PLL), HMC391LP4(VCO) and OP27 (OPAMP).
And the ouput frequency are 3.9GHz or 4.05Ghz and the reference frequency is 50MHz.
Q1) when they implement a charge pump of HMC698, can they implement up/down of charge pump at the same time?
Q2) At this time, can they implement a loop filter circuit as passive type?
Q3) They want to handle a fixed LO as 4.05GHz and 3.9GHz with one OP Amp. (OP27S).
At this time, can they control a tune voltage with under 1V range through OP27S?
Q4)Would you check below their loop filter design?
Please advise me.