Step-up/step-down voltage converter having low output ripple

1. A device for converting an input signal having a given input voltage into an output signal having an output voltage different from the input voltage, the device comprising:

an input terminal adapted to receive the input signal;

an output terminal coupled to a first circuit node and adapted to output the output signal converted from the input signal, wherein the output signal voltage is within one of two or more switching ranges defined by configurations of capacitors in a main module, and wherein the value of the output signal voltage within each switching range is defined by a duty cycle of a pulse-width-modulated (PWM) signal generated by the main module;

the main module disposed operatively between the input terminal and the first circuit node, the main module adapted to output, at the first circuit node, a PWM signal by operating in at least two modes of operation with a given duty cycle, the PWM signal switching with a switching frequency between at least a first voltage value and at least a second voltage value, the first and second voltage values defining one of the at least two switching ranges;

wherein the main module, in a first mode of operation is:

coupled to the input terminal so as to store power from the input signal;

configured to output the first voltage value to the first circuit node;

wherein the main module, in a second mode of operation is configured to output the second voltage value different from the first voltage value to the first circuit node by using power stored during the first mode of operation;

wherein the switching range of the PWM signal has an amplitude, calculated as a difference between the first and second voltage values, less than or equal to half the input voltage.

2. The device of claim 1 , further comprising a low pass filter disposed operatively between the first circuit node and the output terminal, the low pass filter configured to filter at least the switching frequency of the PWM signal.

3. The device of claim 2 , wherein:

the device is adapted to change from a first switching range to a second switching range during use by altering the configuration of capacitors in the main module.

4. The device of claim 1 :

wherein the main module comprises:

at least N capacitor modules, N being an integral number greater or equal to 2;

small switches adapted to arrange the N capacitor modules according to any of the first and second modes of operation of any switching range;

wherein, in the first mode of operation:

the N capacitor modules are connected in series in a chain of capacitor modules between the input terminal and a ground terminal, each capacitor module having a first terminal which is on the side of the input terminal and a second terminal which is on the side of the ground;

the first circuit node is coupled to ground, either directly or through an internal node of the chain of capacitor modules, with J capacitor modules being connected in series between the internal node and the ground terminal, J being an integer between 1 and N inclusive.

5. The device of claim 4 , wherein, in the second mode of operation, L capacitor modules are connected in series between the ground terminal and the first circuit node, such that the first terminal of each capacitor module is on the side of the first circuit node and the second terminal of each capacitor module is on the side of the ground terminal, L being an integer less than or equal to N.

6. The device of claim 5 :

wherein L is an integer greater than zero and less than or equal to N/2;

wherein, in the second mode of operation, the N capacitor modules are arranged in groups of L capacitor modules, the groups being mounted in parallel with each other.

7. The device of claim 4 , wherein, in the second mode of operation, L capacitors modules are connected in series between the first circuit node and the input terminal, such that the second terminal of each capacitor module is on the side of the first circuit node and the first terminal of each capacitor module is on the side of the input terminal, L being an integer less than or equal to N and greater than zero.

8. The device of claim 1 :

wherein the main module is configured to operate according to two modes of operation of a first switching range that is between the two modes of operation of a second switching range;

wherein one of the first and second voltage values of one of the two switching ranges is equal to one of the first or second voltage values of the other of the two switching ranges.

9. The device of claim 1 , further comprising a master module configured to control the main module to operate using two specific modes of operation according to a given switching range and a given duty cycle.

10. The device of claim 9 , wherein the master module is configured to change the switching range and/or the duty cycle that control the main module according to a comparison of a reference signal with the output voltage.

11. The device of claim 10 :

further comprising as many comparators as there are switching ranges,

wherein the master module is configured to generate an error signal based on a comparison of the reference signal and the output voltage, and output the error signal to the comparators in order to create a PWM command signal for each switching range

wherein the master module is configured to control the main module in accordance to a combination of the PWM command signals.

12. A method for converting an input signal, having an input voltage, into a signal different than the input signal, the method comprising:

a main module creating a pulse-width-modulated (PWM) signal by outputting a voltage switching between a first voltage value and a second voltage value different than the first voltage value, with a given duty cycle;

wherein the first and second voltage values define a switching range, and wherein the main module is operative to define at least two different switching ranges by altering a configuration of capacitors;

wherein the PWM signal has an amplitude, calculated as a difference between the first and second voltage values in each switching range, less than or equal to half the input voltage; and

wherein the duty cycle of the PWM signal is operative to determine the output voltage value within each switching range.

13. The method of claim 12 , wherein the PWM signal is smoothed through a low-pass filter to produce an output voltage.

14. The method of claim 12 , wherein the creating the PWM signal comprises:

outputting the first voltage value while storing some power issued from the input voltage in a first mode of operation;

outputting the second voltage value by using the power stored during the first mode of operation in a second mode of operation.