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US 8,804,386 B2Granted
Charge pump circuit with pulse-width modulation
AssigneeST-Ericsson SA
InventorLaurent Chevalier
Life of this patent
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Abstract
Each switching element of a charge pump circuit of a voltage regulator comprises a relatively small-sized MOS transistor associated with a relatively large-sized MOS transistor connected in parallel. Only the small transistors are switched in a first mode of operation, while the large transistors are switched in a second mode of operation. In this manner the switching losses in the first mode of operation can be decreased.
Claims7
Voltage regulator comprising a charge pump circuit with pulse width control and having:
- an output for delivering an output voltage to a load;
- a flying capacitor;
- a charge storage capacitor coupled in parallel to the output;
- a control logic;
- switching elements arranged and controlled by the control logic to charge the flying capacitor in a first phase of operation, and to transfer the electrical charges stored in the flying capacitor to the storage capacitor in a second phase of operation,
- an error signal generator generating an error signal corresponding to the difference between the output voltage from the regulator and a reference voltage;
- a sawtooth wave signal generator generating a sawtooth wave signal;
- and
- a pulse width modulator comparing the error signal and the sawtooth wave signal, and generating switching signals for the switching elements,
- wherein:
- each switching element comprises a relatively small-sized MOS transistor associated with a relatively large-sized MOS transistor connected in parallel and controlled separately;
- only the relatively small-sized transistors are switched in a first mode of operation, while the relatively large-sized transistors are switched in a second mode operation;
- and
- the control logic is configured to cause the regulator to pass from the first mode of operation to the second mode of operation when the error signal is less than a minimum value for the sawtooth wave signal.
11 more elements
Voltage regulation method using a charge pump circuit with pulse-width control and having:
- an output for delivering an output voltage to a load;
- a flying capacitor;
- a charge storage capacitor coupled in parallel to the output;
- a control logic;
- and
- switching elements arranged and controlled by the control logic to charge the flying capacitor in a first phase of operation, and to transfer the electrical charges stored in the flying capacitor to the storage capacitor in a second phase of operation,
- each switching element comprising a relatively small-sized MOS transistor associated with a relatively large-sized MOS transistor, connected in parallel and controlled separately,
- the method comprising:
- generating an error signal corresponding to the difference between the output voltage from the regulator and a reference voltage;
- generating a sawtooth wave signal;
- comparing the error signal and the sawtooth wave signal using a pulse width modulator, and generating switching signals for the switching elements such that, only the relatively small-sized transistors are switched in a first mode of operation while the relatively large-sized transistors are switched in a second mode of operation;
- and
- passing from the first mode of operation to the second mode of operation when an error signal corresponding to the difference between the output voltage and the reference voltage is less than a minimum value of the sawtooth signal.
10 more elements
Dependencies are inferred from the claim text.