STABILITY METHODS AND STRUCTURES FOR CURRENT-MODE DC-DC VOLTAGE CONVERTERS
First Claim
1. A voltage converter system to thereby generate an output voltage at an output port in response to an input voltage at an input port, comprising:
- a switching voltage converter arranged to switch through a first transistor a first current with a rising slope and subsequently switch through a second transistor a second current with a falling slope;
a voltage feedback circuit arranged to generate an error voltage in response to the difference between said output voltage and a reference voltage;
a current feedback circuit arranged to provide a feedback voltage ramp in proportional response to said rising slope; and
a controller configured to sum a compensation voltage ramp having a compensation rising slope with said feedback voltage ramp to provide a summed voltage ramp to compare with said error voltage to thereby control duty cycles of said first and second transistors.
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Accused Products
Abstract
DC-DC voltage converter structures and methods are provided that employ first and second transistors which are switched to control currents through an inductor and a capacitor to thereby provide an output voltage substantially equal to a predetermined reference voltage. Preferably included is a voltage feedback loop in which an error voltage is fed back to a loop comparator and further included is a current feedback loop that provides to the comparator a first voltage ramp whose amplitude is proportional to the amplitude of the converter'"'"'s input current. The output signal of the comparator sets the duty cycles of the first and second transistors. In each converter period, the first and second transistors of the voltage converter respectively control, through the inductor, a first current with a rising slope and a second current with a falling slope. Finally, converter stability is enhanced by providing a second voltage ramp having a slope related to a fraction (e.g., ½) of the falling slope and then comparing the error voltage of the voltage feedback loop to the sum of the first and second voltage ramps.
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Citations
20 Claims
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1. A voltage converter system to thereby generate an output voltage at an output port in response to an input voltage at an input port, comprising:
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a switching voltage converter arranged to switch through a first transistor a first current with a rising slope and subsequently switch through a second transistor a second current with a falling slope; a voltage feedback circuit arranged to generate an error voltage in response to the difference between said output voltage and a reference voltage; a current feedback circuit arranged to provide a feedback voltage ramp in proportional response to said rising slope; and a controller configured to sum a compensation voltage ramp having a compensation rising slope with said feedback voltage ramp to provide a summed voltage ramp to compare with said error voltage to thereby control duty cycles of said first and second transistors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A voltage converter system to thereby generate an output voltage at an output port in response to an input voltage at an input port, comprising:
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a switching voltage converter arranged to switch, for a controlled time period, through a first transistor a first current with a rising slope and subsequently switch through a second transistor a second current with a falling slope; a voltage feedback circuit arranged to generate an error voltage in response to the difference between said output voltage and a reference voltage; a current feedback circuit arranged to provide a feedback voltage ramp in proportional response to said rising slope; a duty generator configured to obtain a controlled time period during which said first transistor is switched on; a current generator coupled to provide a compensation current related to said controlled time period; a capacitor coupled to provide, in response to said compensation current, a compensation voltage ramp having a compensation rising slope; and a summer to provide, in response to said feedback voltage ramp and said compensation voltage ramp, a summed voltage ramp to compare with said error voltage to thereby control duty cycles of said first and second transistors. - View Dependent Claims (13, 14, 15, 16)
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17. A method to generate an output voltage at an output port in response to an input voltage at an input port, comprising the steps of:
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switching through a first transistor a first current with a rising slope and subsequently switch through a second transistor a second current with a falling slope; with a voltage feedback circuit, generating an error voltage in response to the difference between said output voltage and a reference voltage; with a current feedback circuit, providing a feedback voltage ramp in proportional response to said rising slope; and summing a compensation voltage ramp having a compensation rising slope with said feedback voltage ramp to provide a summed voltage ramp to compare with said error voltage to thereby control duty cycles of said first and second transistors. - View Dependent Claims (18, 19, 20)
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Specification