Patent ID: 6819190
Filing Date: 2004-11-16
Classification: H02M,H03K,H03L

Abstract:
An apparatus comprising:a pulse width modulation (PWM) generator which generates a PWM signal; and a controller for controlling the operation of said PWM generator, said controller including a multistage delay line coupled to a phase detector, to which a reference signal, being either a system clock or a pulse stream constructed from integer cycles of a system clock, is coupled, said phase detector producing an output that controls an operational parameter of said multistage delay line, said multistage delay line being coupled to establish the duty-cycle of said PWM signal, wherein said multistage delay line is configured as a closed loop circuit forming a ring oscillator of a phase locked loop (PLL) containing said phase detector, and further including a tapped delay line having a plurality of delay stages corresponding to respective delay line stages of said multistage delay line, and wherein said phase detector produces an output that controls said operational parameter of each of said multistage delay line and said tapped delay line, further including a logical combining circuit coupled to combine a delayed output of a selected delay stage of said tapped delay line and a prescribed pulse signal applied to an input stage of said tapped delay line, and being operative to produce a fractionally extended version of said prescribed pulse signal for establishing the duty-cycle of said PWM signal.