Charge pump circuit with a brief settling time and high output voltage regulation precision
View Patent ↗A circuit for converting a direct current input voltage into an output voltage greater than the input voltage. The circuit includes a charge pump and a block for generating pulse signals of a predetermined frequency to be applied to a control input of the charge pump. The settling time, i.e. the time necessary for the output voltage to attain its operating value and to maintain it with a given precision, is reduced by providing the circuit with charge injection control via modulation of the duty cycle of the pulse signals as a function of the difference between the output voltage, or a predetermined fraction thereof, and a predetermined reference voltage and in such a manner as to reduce the settling time as the difference diminishes. The circuit includes a regulator that controls the charge pump based upon the predetermined reference voltage.
1. A circuit for converting an input voltage into an output voltage greater than the input voltage comprising:
a charge pump including a control input;
a pulse signal generator for generating pulse signals of a frequency to be applied to the control input of the charge pump; and
a regulator for regulating the duty cycle of the pulse signals based upon a difference between at least a part of the output voltage and a reference voltage so that the duty cycle is reduced as the difference decreases.
2. A circuit according to claim 1 , wherein the duty cycle is regulated in a discrete manner.
3. A circuit according to claim 1 , wherein the duty cycle is regulated in a continuous manner.
4. A circuit according to claim 1 , wherein the regulator comprises:
at least one comparator having a first input receiving the output voltage, a second input receiving a intermediate reference voltage less than the reference voltage, and an output; and
a pulse width modulator having a first input receiving a clock signal, a control input connected to the output of the at least one comparator, and an output connected to the control input of the charge pump.
5. A circuit according to claim 1 , wherein the regulator comprises:
at least one comparator having a first input receiving the output voltage, a second input receiving a intermediate reference voltage less than the reference voltage, and an output; and
a plurality of pulse width modulators, each of which has a first input receiving a clock signal, a second input, and an output connected to the control input of the charge pump, to modify the duty cycle of the clock signal in a manner different from the other pulse width modulators of the plurality of pulse width modulators; and
a selection logic unit having an input connected to the output of the at least one comparator, and a plurality of selection outputs, each of which is connected to a second input of one of the plurality of pulse width modulators for selective activation of the modulators.
6. A circuit according to claim 1 , wherein the regulator comprises:
a control logic unit having a first input receiving the output voltage, a second input receiving the reference voltage, and an output;
a plurality of pulse width modulators, each of which has a first input receiving a clock signet, a second input, and an output connected to the control input of the charge pump, to modify the duty cycle of the clock signal in a manner different from the other pulse width modulators of the plurality of pulse width modulators; and
a selection logic unit having an input connected to the output of the control logic unit, and a plurality of selection outputs, each of which is connected to a second input of one of the plurality of pulse width modulators for selective activation of the modulators.
7. A circuit according to claim 1 , wherein the regulator comprises a control and pulse width modulating unit having a first modulation input receiving the output voltage, a second input receiving the reference voltage, a third input receiving a clock signal, and an output connected to the control input of the charge pump, the control and pulse width modulating unit also defining the pulse signal generator.
8. A circuit according to claim 1 , further comprising a feedback regulator receiving the output voltage and for controlling the charge pump based upon the output voltage and the reference voltage.
9. A circuit according to claim 4 , further comprising a feedback regulator receiving the output voltage and for controlling the charge pump based upon the output voltage and the reference voltage; wherein the pulse signal generator comprises a transducer circuit connected between the output of the pulse width modulator and the control input of the charge pump and having an enabling/disabling input connected to the feedback regulator.
10. A circuit according to claim 5 , further comprising a feedback regulator receiving the output voltage and for controlling the charge pump based upon the output voltage and the reference voltage; wherein the pulse signal generator comprises an enabling/disabling unit that defines part of the selection logic unit and is connected to the feedback regulator.
11. A circuit according to claim 6 , further comprising a feedback regulator receiving the output voltage and for controlling the charge pump based upon the output voltage and the reference voltage; wherein the pulse signal generator comprises an enabling/disabling unit that defines part of the selection logic unit and is connected to the feedback regulator.
12. A circuit according to claim 10 wherein the feedback regulator comprises a comparator having a first input receiving the output voltage, a second input receiving the reference voltage and an output connected to the selection logic unit.
13. A circuit according to claim 7 , wherein the control and modulation logic unit further comprises a feedback regulator receiving the output voltage and for controlling the charge pump based upon the output voltage and the reference voltage.
14. A device comprising:
a multilevel non-volatile memory; and
a circuit, associated with the memory, for converting an input voltage into an output voltage greater than the input voltage comprising
a charge pump including a control input,
a pulse signal generator for generating pulse signals of a frequency to be applied to the control input of the charge pump, and
a regulator for regulating the duty cycle of the pulse signals based upon a difference between at least a part of the output voltage and a reference voltage so that the duty cycle is reduced as the difference decreases.
15. A device according to claim 14 , wherein the duty cycle is regulated in a discrete manner.
16. A device according to claim 14 , wherein the duty cycle is regulated in a continuous manner.
17. A method for converting an input voltage into an output voltage greater than the input voltage comprising:
providing a charge pump including a control input;
generating pulse signals of a frequency with a pulse signal generator to be applied to the control input of the charge pump; and
regulating the duty cycle of the pulse signals based upon a difference between at least a part of the output voltage and a reference voltage so that the duty cycle is reduced as the difference decreases.
18. A method according to claim 17 , wherein the duty cycle is regulated in a discrete manner.
19. A method according to claim 17 , wherein the duty cycle is regulated in a continuous manner.
20. A method according to claim 17 , wherein regulating the duty cycle comprises providing a regulator including:
at least one comparator having a first input receiving the output voltage, a second input receiving a intermediate reference voltage less than the reference voltage, and an output; and
a pulse width modulator having a first input receiving a clock signal, a control input connected to the output of the at least one comparator, and an output connected to the control input of the charge pump.
21. A method according to claim 17 , wherein regulating the duty cycle comprises providing a regulator including:
at least one comparator having a first input receiving the output voltage, a second input receiving a intermediate reference voltage less than the reference voltage, and an output; and
a plurality of pulse width modulators, each of which has a first input receiving a clock signal, a second input, and an output connected to the control input of the charge pump, to modify the duty cycle of the clock signal in a manner different from the other pulse width modulators of the plurality of pulse width modulators; and
a selection logic unit having an input connected to the output of the at least one comparator, and a plurality of selection outputs, each of which is connected to a second input of one of the plurality of pulse width modulators for selective activation of the modulators.
22. A method according to claim 17 , wherein regulating the duty cycle comprises providing a regulator including:
a control logic unit having a first input receiving the output voltage, a second input receiving the reference voltage, and an output;
a plurality of pulse width modulators, each of which has a first input receiving a clock signal, a second input, and an output connected to the control input of the charge pump, to modify the duty cycle of the clock signal in a manner different from the other pulse width modulators of the plurality of pulse width modulators; and
a selection logic unit having art input connected to the output of the control logic unit, and a plurality of selection outputs, each of which is connected to a second input of one of the plurality of pulse width modulators for selective activation of the modulators.
23. A method according to claim 17 , wherein regulating the duty cycle comprises providing a regulator including a control and pulse width modulating unit having a first modulation input receiving the output voltage, a second input receiving the reference voltage, a third input receiving a clock signal, and an output connected to the control input of the charge pump, the control and pulse width modulating unit also defining the pulse signal generator.
24. A method according to claim 17 , further comprising controlling the charge pump based upon the output voltage and the reference voltage with a feedback regulator receiving the output voltage.
25. A method according to claim 20 , further comprising controlling the charge pump based upon the output voltage and the reference voltage with a feedback regulator receiving the output voltage; wherein the pulse signal generator comprises a transducer circuit connected between the output of the pulse width modulator and the control input of the charge pump and having an enabling/disabling input connected to the feedback regulator.
26. A method according to claim 21 , further comprising controlling the charge pump based upon the output voltage and the reference voltage with a feedback regulator receiving the output voltage; wherein the pulse signal generator comprises an enabling/disabling unit that defines part of the selection logic unit and is connected to the feedback regulator.
27. A method according to claim 22 , further comprising controlling the charge pump based upon the output voltage and the reference voltage with a feedback regulator receiving the output voltage; wherein the pulse signal generator comprises an enabling/disabling unit that defines part of the selection logic unit and is connected to the feedback regulator.
28. A method according to claim 27 wherein the feedback regulator comprises a comparator having a first input receiving the output voltage, a second input receiving the reference voltage and an output connected to the selection logic unit.