By varying f m and f r with N constant. It is helpful to consider the PLL in terms of phase rather than frequency. Table 1 shows the transfer functions of the various loop elements with this change made, and Figure 2 shows the circuit. K 0 is tho slope of the oscillator frequency to voltage characteristic in rads per sec. N is division ratio.
Transfer function depends on the type of filter used.
By changing the phase, of the mixing frequency. By changing the phase, of the reference frequency. By changing voltage V at the modulation port. Where V is the voltage input at the modulation port. The choice of the phase detector is determined primarily by the application.