hmc4069 PD output : +/-5V (pin NU, ND)， charge pump current is 10mA;
suppose vco tuning voltage is 0~15V.
As you see, they are not equal , and the latter（15V） is higher than former（5V)
As the datasheet recommemded , the loop filer is one op circuits , more likely a differential amp.
for AC signal , if the gain of amp >1, (for example , gain=3), the op can convert 5Vpp to 15Vpp.
but for pll, the input signal is a pulse signal.
my question is : can this circuit convert +/-5V pulse signal to a stable 15V tuning voltage ?
or it is more likely a integration circuits? once the tuning voltage is not reached, the pulse sigal will continue be produced.
and is there any other requirement for op, like VCC/VSS must be +/-15V likewise ?
Yes it is possible to use the gain from the op amp in the active filter to tune over a wide vtune range such as 0 - 15V. So the loop filter here also acts as an amplifier. It also functions as an integrator…