Glue-logic based method and system for minimizing losses in oversampled digitally controlled DC-DC converters
View Patent ↗A practical method and system for oversampled digitally controlled DC-DC converters is presented. To minimize the switching losses while maintaining all advantages of the oversampling, “glue logic” and application specific oversampling digital pulse-width modulator are introduced. Experimental results demonstrate transient response with 50% smaller deviation than that of conventional controllers, allowing for proportional reduction in the size of the power stage output capacitor.
1. A digital pulse width modulator (DPWM) producing a pulse width modulation (PWM) output signal at a first frequency during a first period, the DPWM using an over sampled feedback signal sampled at a second frequency greater than the first frequency; wherein during an output voltage deviation period, the DPWM produces a modified PWM signal using the oversampled feedback signal, the modified PWM signal being limited to a third frequency that is between the first and second frequency.
2. The DPWM of claim 1 , wherein a pulse glue generator produces a signal to be added or subtracted to the normal PWM signal during output voltage deviations.
3. The DPWM of claim 1 , wherein the second frequency is four times the first frequency and the third frequency is two times the first frequency.
4. The DPWM of claim 1 , wherein the feedback signal is an error signal.
5. The DPWM of claim 1 , further comprising:
a circuit to determine output voltage transients and to enable the modification of the normal PWM signal.
6. The DPWM of claim 1 , wherein during an output voltage deviation, the DPWM adds or subtracts extra pulses to the normal PWM signal.
7. The DPWM of claim 6 , wherein the extra pulses are arranged such that the PWM output does not exceed the third frequency.
8. A digital pulse width modulator (DPWM) producing a pulse width modulation (PWM) at a first frequency during a first period, the DPWM using an over sampled feedback signal sampled at an oversampling frequency that is greater than the first frequency, wherein during an output voltage deviation period, the DPWM uses the oversampled feedback signal to determine extra pulses to be added or subtracted from the normal PWM signal to produce a modified PWM signal, wherein the extra pulses are such that the frequency of the modified PWM signal is limited to half the oversampling frequency or less.
9. The DPWM of claim 8 , wherein a pulse glue generator produces a signal to be added or subtracted to the normal PWM signal during output voltage deviations.
10. The DPWM of claim 8 , wherein the oversampling frequency is four times the first frequency and the frequency of the modified PWM signal is two times the first frequency.
11. The DPWM of claim 8 , wherein the feedback signal is an error signal.
12. The DPWM of claim 8 further comprising:
a circuit to determine output voltage transients and to enable the modification of the normal PWM signal.
13. A method comprising:
producing a pulse width modulator (PWM) signal at a first frequency during a first period;
oversampling a feedback signal at a second frequency;
using the oversampled feedback signal to determine an output voltage deviation period; and
during the output voltage deviation period, adding or subtracting pulses to the PWM signal to produce a modified PWM signal, the modified PWM signal being limited to a third frequency that is between the first and second frequency.
14. The method of claim 13 , wherein a pulse glue generator produces a signal to be added or subtracted to the normal PWM signal during the output voltage deviations.
15. The method of claim 13 , wherein the second frequency is four times the first frequency and the third frequency is two times the first frequency.
16. The method of claim 13 , wherein the feedback signal is an error signal.