DC-DC converters with transient response control
A DC-DC converter used to convert an input voltage to an output voltage is disclosed. The DC-DC converter comprises a pulse-width-modulation (PWM) generator, a transient boost circuit, a logic circuit, a switching device, and a buck circuit. The pulse-width-modulation (PWM) generator generates a PWM signal according to the output voltage. The transient boost circuit generates an adjusting signal according to the variation of the output voltage. The logic circuit generates a switch signal according to the PWM signal and the adjusting signal. The switching signal is at a high level when the PWM signal or the adjusting signal is at the high level, and the switching signal is at a low level when the PWM signal and the adjusting signal are at the low level. The switching device converts the input voltage to a driving signal according to the switching signal. The buck circuit receives the driving signal to generate the output voltage.
1. A DC-DC converter used to convert an input voltage to an output voltage, comprising:
a pulse-width-modulation (PWM) generator configured to generate a PWM signal according to the output voltage;
a transient boost circuit configured to generate an adjusting signal according to the variation of the output voltage;
a logic circuit configured to generate a switch signal, wherein the switching signal is at a high level when the PWM signal or the adjusting signal is at the high level and the switching signal is at a low level when the PWM signal and the adjusting signal are at the low level;
a switching device configured to convert the input voltage to a driving signal according to the switching signal; and
a buck circuit configured to receive the driving signal to generate the output voltage.
2. The DC-DC converter as claimed in claim 1 , wherein the transient boost circuit further comprises:
an offset adjustment circuit configured to receive the output voltage to generate a transient boost voltage having a voltage offset corresponding to a steady state of the output voltage; and
a comparator configured to compare the output voltage with the transient boost voltage to generate the adjusting signal.
3. The DC-DC converter as claimed in claim 2 , wherein the adjusting signal is at the high level when the transient boost voltage is higher than the output voltage, and the adjusting signal is at the low level when the transient boost voltage is lower than the output voltage.
4. The DC-DC converter as claimed in claim 2 , wherein the offset adjustment circuit further comprises:
a capacitor, coupled to a non-inverting terminal of the comparator, configured to sustain the transient boost voltage;
a current source, coupled to the non-inverting terminal, configured to generate a current; and
a resistor, coupled between a inverting terminal of the comparator and the non-inverting terminal, configured to generate the voltage offset.
5. The DC-DC converter as claimed in claim 4 , wherein the voltage offset is generated as a resistance of the resistor multiplied by the current.
6. The DC-DC converter as claimed in claim 1 , wherein the transient boost circuit further comprises:
a capacitor configured to sustain a transient boost voltage; and
a comparator, having an inverting terminal coupled to the output voltage and a non-inverting terminal coupled to the capacitor, configured to compare the output voltage with the transient boost voltage to generate the adjusting signal, wherein the comparator has an input offset between the inverting and non-inverting terminals.
7. The DC-DC converter as claimed in claim 6 , wherein the adjusting signal is at the high level when the output transient boost voltage is higher than the output voltage, and the adjusting signal is at the low level when the output transient boost voltage is lower than the output voltage.
8. The DC-DC converter as claimed in claim 1 , wherein the logical circuit is an OR gate.
9. A multi-phase DC-DC converter used to convert an input voltage to an output voltage, comprising:
a plurality of pulse-width-modulation (PWM) generators configured to generate PWM signals according to the output voltage;
a transient boost circuit configured to generate an adjusting signal according to the variation of the output voltage;
a plurality of logic circuits configured to generate switch signals each corresponding to one of the PWM signals, wherein the switching signal is at a high level when the corresponding PWM signal or the adjusting signal is at the high level and the switching signal is at a low level when the corresponding PWM signal and the adjusting signal are at the low level;
a plurality of switching devices configured to convert the input voltage to driving signals according to the switching signals; and
a buck circuit configured to receive the driving signals to generate the output voltage.
10. The multi-phase DC-DC converter as claimed in claim 9 , wherein the transient boost circuit further comprises:
an offset adjustment circuit configured to receive the output voltage to generate a transient boost voltage having a voltage offset corresponding to a steady state of the output voltage; and
a comparator configured to compare the output voltage with the transient boost voltage to generate the adjusting signal, wherein the adjusting signal is at the high level when the transient boost voltage is higher than the output voltage, and the adjusting signal is at the low level when the transient boost voltage is lower than the output voltage.
11. The multi-phase DC-DC converter as claimed in claim 10 , wherein the transient boost circuit further comprises:
a capacitor, coupled to a non-inverting terminal of the comparator, configured to sustain the transient boost voltage;
a current source, coupled to the non-inverting terminal, configured to generate a current; and
a resistor, coupled between a inverting terminal of the comparator and the non-inverting terminal, configured to generate the voltage offset.
12. The multi-phase DC-DC converter as claimed in claim 11 , wherein the voltage offset is generated as a resistance of the resistor multiplied by the current.
13. The multi-phase DC-DC converter as claimed in claim 9 , wherein the transient boost circuit further comprises:
a capacitor configured to sustain a transient boost voltage; and
a comparator, having an inverting terminal coupled to the output voltage and a non-inverting terminal coupled to the capacitor, configured to compare the output voltage with the transient boost voltage to generate the adjusting signal, wherein the comparator has an input offset between the inverting and non-inverting terminals, and the transient boost voltage is equal to a steady state of the output voltage minus the input offset.
14. The multi-phase DC-DC converter as claimed in claim 9 , wherein each logical circuit is an OR gate.
15. A multi-phase DC-DC converter used to convert an input voltage to an output voltage, comprising:
a plurality of pulse-width-modulation (PWM) generators configured to generate PWM signals according to the output voltage;
a plurality of transient boost circuits configured to generate adjusting signals according to the variation of the output voltage;
a plurality of logic circuits configured to generate switch signals each corresponding to one of the PWM signals and one of the adjusting signals, wherein the switching signal is at a high level when the corresponding PWM signal or the corresponding adjusting signal is at the high level and the switching signal is at a low level when the corresponding PWM signal and the corresponding adjusting signal are at the low level;
a plurality of switching devices configured to convert the input voltage to driving signals according to the switching signals; and
a buck circuit configured to receive the driving signals to generate the output voltage.
16. The multi-phase DC-DC converter as claimed in claim 15 , wherein each transient boost circuit further comprises:
an offset adjustment circuit configured to receive the output voltage to generate a transient boost voltage having a voltage offset corresponding to a steady state of the output voltage; and
a comparator configured to compare the output voltage with the transient boost voltage to generate the adjusting signal.
17. The multi-phase DC-DC converter as claimed in claim 16 , wherein the adjusting signal is at the high level when the transient boost voltage is higher than the output voltage, and the adjusting signal is at the low level when the transient boost voltage is lower than the output voltage.
18. The multi-phase DC-DC converter as claimed in claim 15 , wherein the transient boost circuit further comprises:
a capacitor configured to sustain a transient boost voltage; and
a comparator, having an inverting terminal coupled to the output voltage and a non-inverting terminal coupled to the capacitor, configured to compare the output voltage with the transient boost voltage to generate the adjusting signal.
19. The multi-phase DC-DC converter as claimed in claim 18 , wherein the comparator has an input offset between the inverting and non-inverting terminals, and the transient boost voltage is equal to a steady state of the output voltage minus the input offset.
20. The multi-phase DC-DC converter as claimed in claim 15 , wherein each logical circuit is an OR gate.
21. The DC-DC converter as claimed in claim 1 , further comprising:
a feedback circuit generating a feedback signal according to the output voltage;
an error amplifier comparing the feedback signal with a reference voltage to generate a comparison signal, wherein the pulse-width-modulation (PWM) generator generates the PWM signal according to the comparison signal and a ramp signal generated from a ramp oscillator.
22. The DC-DC converter as claimed in claim 21 , further comprising a compensation circuit coupled between the feedback circuit and the pulse-width-modulation (PWM) generator, and mitigating a variation of the comparison signal.
23. The multi-phase DC-DC converter as claimed in claim 9 , further comprising:
a feedback circuit generating a feedback signal according to the output voltage;
an error amplifier comparing the feedback signal with a reference voltage to generate a comparison signal, wherein the plurality of pulse-width-modulation (PWM) generators generate the PWM signals according to the comparison signal and a ramp signal generated from a ramp oscillator.
24. The multi-phase DC-DC converter as claimed in claim 23 , further comprising a compensation circuit coupled between the feedback circuit and the plurality of pulse-width-modulation (PWM) generators, and mitigating a variation of the comparison signal.
25. The multi-phase DC-DC converter as claimed in claim 15 , further comprising:
a feedback circuit generating a feedback signal according to the output voltage;
an error amplifier comparing the feedback signal with a reference voltage to generate a comparison signal, wherein the plurality of pulse-width-modulation (PWM) generators generate the PWM signals according to the comparison signal and a ramp signal generated from a ramp oscillator.
26. The multi-phase DC-DC converter as claimed in claim 25 , further comprising a compensation circuit coupled between the feedback circuit and the plurality of pulse-width-modulation (PWM) generators, and mitigating a variation of the comparison signal.