CONTINUOUSLY VARIABLE SWITCHED CAPACITOR DC-DC VOLTAGE CONVERTER
A voltage converter is switched among two or more modes to produce an output voltage matching a reference voltage that can be of an intermediate level between discrete levels corresponding to the modes. The output voltage is compared with the reference voltage to determine whether to adjust the mode.
1 . A voltage converter, comprising:
a switch matrix having a plurality of mode configurations, each mode configuration corresponding to one of a plurality of output signal voltages, the mode configuration being selectable in response to a mode control signal;
comparator logic implemented to compare the output signal with a reference signal and produce a direction comparison signal; and
control logic implemented to produce the mode control signal in response to the direction comparison signal.
2 . The voltage converter of claim 1 , wherein each mode configuration is defined by a capacitor circuit having a plurality of capacitors interconnected with each other between a voltage potential and an output node.
3 . The voltage converter of claim 2 , wherein each mode configuration has a first phase configuration in which the capacitor circuit is charged and a second phase configuration in which the capacitor circuit is discharged.
4 . The voltage converter of claim 3 , wherein the switch matrix switches between the first phase configuration and the second phase configuration of a selected mode configuration in response to a clock signal to produce an output signal at the output node having an output signal voltage corresponding to the selected mode configuration.
5 . The voltage converter of claim 1 , wherein the direction comparison signal indicates which of the output signal and the reference signal is greater.
6 . The voltage converter of claim 5 , wherein the control logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage greater than the reference signal in response to the direction comparison signal indicating that the reference signal is greater than the output signal, and the control logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage less than the reference signal in response to the direction comparison signal indicating that the output signal is greater than the reference signal.
7 . The voltage converter of claim 1 , wherein the switch matrix has three mode configurations.
8 . The voltage converter of claim 7 , wherein the three mode configurations include a first mode configuration corresponding to an output signal voltage of one-third of a base reference voltage, a second mode configuration corresponding to an output signal voltage of one-half of the base reference voltage, and a third mode configuration corresponding to an output signal voltage of two-thirds of the base reference voltage.
9 . The voltage converter of claim 8 , wherein the comparator logic includes a plurality of comparators and a voltage level generator circuit that generates a plurality of reference voltage levels and provides a selected reference voltage level to a first input of each comparator, each voltage level corresponding to one of the plurality of output signal voltages, the second input of each comparator coupled to the output signal, each comparator providing a corresponding comparison signal.
10 . The voltage converter of claim 9 , wherein the plurality of comparators comprises three comparators.
11 . The voltage converter of claim 10 , wherein a first comparator compares the output signal with a first reference voltage signal having a voltage of a first fraction of a base reference voltage and produces a first comparison signal.
12 . The voltage converter of claim 11 , wherein the first comparison signal indicates whether the output signal voltage exceeds the first fraction of the base reference voltage.
13 . The voltage converter of claim 11 , wherein a second comparator compares the output signal with a second reference voltage signal having a voltage of a second fraction of a base reference voltage greater than the first fraction of the base reference voltage and produces a second comparison signal.
14 . The voltage converter of claim 13 , wherein the second comparison signal indicates whether the output signal voltage exceeds the second fraction of the base reference voltage.
15 . The voltage converter of claim 13 , wherein a third comparator compares the output signal with a third reference voltage having a voltage of a third fraction of a base reference voltage greater than the second fraction of the base reference voltage signal and produces a third comparison signal.
16 . The voltage converter of claim 15 , wherein the third comparison signal indicates whether the output signal voltage exceeds the third fraction of the base reference voltage.
17 . The voltage converter of claim 15 , wherein the three mode configurations include a first mode configuration corresponding to an output signal voltage of the first fraction of the base reference voltage, a second mode configuration corresponding to an output signal voltage of the second fraction of the reference voltage, and a third mode configuration corresponding to an output signal voltage of the third fraction of the reference voltage.
18 . The voltage converter of claim 17 , wherein the first fraction is one-third, the second fraction is one-half and the third fraction is two-thirds.
19 . The voltage converter of claim 17 , wherein the control logic comprises combinational logic responsive to combinations of the first, second and third comparison signals.
20 . The voltage converter of claim 19 , wherein the combinational logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage of the first fraction of the base reference voltage if the first comparison signal indicates that the output signal voltage does not exceed the first fraction of the base reference voltage and the direction comparison signal indicates that the reference signal is greater than the output signal.
21 . The voltage converter of claim 19 , wherein the combinational logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage of the first fraction of the base reference voltage if the first comparison signal indicates that the output signal voltage exceeds the first fraction of the base reference voltage, the second comparison signal indicates that the output voltage does not exceed the second fraction of the base reference voltage, and the direction comparison signal indicates that the reference signal is less than the output signal.
22 . The voltage converter of claim 19 , wherein the combinational logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage of the second fraction of the base reference voltage if the first comparison signal indicates that the output signal voltage exceeds the first fraction of the base reference voltage, the second comparison signal indicates that the output voltage does not exceed the second fraction of the base reference voltage, and the direction comparison signal indicates that the reference signal is greater than the output signal.
23 . The voltage converter of claim 19 , wherein the combinational logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage of the second fraction of the base reference voltage if the second comparison signal indicates that the output voltage exceeds the second fraction of the base reference voltage, the third comparison signal indicates that the output voltage does not exceed the third fraction of the base reference voltage, and the direction comparison signal indicates that the reference signal is less than the output signal.
24 . The voltage converter of claim 19 , wherein the combinational logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage of the third fraction of the base reference voltage if the second comparison signal indicates that the output voltage exceeds the second fraction of the base reference voltage, the third comparison signal indicates that the output voltage does not exceed the third fraction of the base reference voltage, and the direction comparison signal indicates that the reference signal is greater than the output signal.
25 . The voltage converter of claim 19 , wherein the combinational logic produces the mode control signal to select a mode configuration corresponding to an output signal voltage of the third fraction of the base reference voltage if the third comparison signal indicates that the output voltage exceeds the third fraction of the base reference voltage and the direction comparison signal indicates that the reference signal is less than the output signal.