In this paper, the phase locked loop that employs digital phase detector circuit along with applying an input signal either in front of a loop filter, or behind a loop filter, or at the position of a reference signal is presented and analyzed. The modified PLL circuit can be applied for a PWM generator, or a PPM generator, or a phase shifter. Moreover, frequency response of the PLL that is injected with input signal at any position as mention above is given. Finally, the application of PLL as a FM to PWM and a FM to PPM converter, with and without carrier include phase shift are also proposed. The experimental results show that they agree well with those obtained from theoretical and simulation parts.

pulse width modulation, pulse position modulation, phase locked loop.