A PLL operates with input and output frequencies equal to f1. Suppose the input frequency and hence the output frequency are changed to f1/2. Assuming all loop parameters remain unchanged and neglecting the continuous-time approximation issues, explain which one of these arguments is correct and why the other one is not:
(a) The PFD now makes half as many phase comparisons per second, pumping half as much charge into the loop filter. Thus, the loop is less stable.
(b).
