Variable stage charge pump and method for providing boosted output voltage
An embodiment of a variable stage charge pump includes a plurality of pump stages. Each stage is configured to generate an intermediate boosted output voltage. A pump stage selector selects the number of charge pump stages to be coupled between an input and output terminal of the variable stage charge pump. The pump stage selector may control a plurality of switches to select the number of stages. For example, two stages maybe coupled in parallel and the parallel combination coupled in series to a third stage, resulting in a two stage charge pump. For a three stage charge pump, all three stages are coupled in series.
1. A charge pump, comprising:
first, second, and third stages, each stage configured to receive a respective input voltage and provide a respective pumped voltage; and
a pump stage selector configured to control a configuration of the charge pump, in a first configuration, the first, second, and third stages are coupled in series, and in a second configuration, an output of the first stage is coupled to an input of the second stage and an input of the third stage to provide the pumped voltage from the first stage to the second and third stages concurrently.
2. The charge pump of claim 1 , further comprising a set of switches coupled to the first, second, and third stages, the set of switches configured to couple the first, second, and third stages accordingly to provide the first and second configurations as controlled by the pump stage selector.
3. The charge pump of claim 2 , wherein the set of switches are coupled between outputs of the first and second stages and the third stage.
4. The charge pump of claim 1 , wherein the pump stage selector is configured to control the configuration of the charge pump between the first and second configurations based at least in part on an input source voltage, an output driving requirement, an output voltage requirement, or combinations thereof.
5. The charge pump of claim 1 wherein the pump stage selector is configured to control the configuration of the charge pump between the first and second configurations based at least in part on an absolute threshold voltage, an absolute circuit parameter, or combinations thereof.
6. The charge pump of claim 1 wherein the pump stage selector is configured to compare a reference voltage to a voltage based on a power supply voltage, the pump stage selector further configured to select between the first and second configurations and based at least in part on the comparison.
7. The charge pump of claim 1 wherein the pump stage selector is further configured to control the configuration of the charge pump in a third configuration, the third configuration corresponding to a one-stage configuration.
8. The charge pump of claim 1 , wherein the pump stage selector is further configured to control the configuration of the charge pump, in the second configuration, to couple outputs of the second and third stages to an output of the charge pump.
9. A charge pump, comprising:
a plurality of pump stages, each pump stage configured to provide receive a respective output voltage responsive to a respective input voltage; and
a pump stage selector configured to control configuration of the charge pump, in a first configuration, an output voltage of a first pump stage is provided to a second pump stage, and an output voltage of the second pump stage is provided to a third pump stage, and the output of the third pump stage is provided as a final output voltage from the charge pump, and in a second configuration, an output voltage of the first stage is provided to the second and third stages and output voltages of the second and third stages are combined to provide the final output voltage from the charge pump.
10. The charge pump of claim 9 , wherein the second configuration provides greater current driving capacity than in the first configuration.
11. The charge pump of claim 9 , further comprising a voltage regulator coupled to an output of the charge pump and configured to enable the charge pump based at least in part on an output voltage of the charge pump and a reference voltage.
12. The charge pump of claim 11 , wherein the voltage regulator is configured to turn on a clock signal used to drive the charge pump to enable the charge pump.
13. The charge pump of claim 11 , further comprising a reference voltage generator coupled to the voltage regulator and configured to provide the reference voltage.
14. The charge pump of claim 13 , wherein the reference voltage generator comprises a bandgap voltage generator.
15. The charge pump of claim 14 , wherein the reference voltage generator further comprises a resistor divider coupled to the bandgap voltage generator.
16. A charge pump, comprising:
a plurality of charge pump stages, each stage configured to receive a respective input voltage and generate a respective pumped voltage therefrom and provide the pumped voltage to a respective output terminal;
a pump stage selector configured to control configuration of first, second, and third charge pump stages of the plurality of charge pump stages, in a first configuration the first, second, and third pump stages are serially coupled and in a second configuration the second and third pump stages are coupled in parallel and the first pump stage is coupled to provide an output voltage to the parallel-coupled second and third pump stages, the pump stage selector further configured to change the configuration of the first, second, and third charge pump stages based at least in part on a voltage regulator signal; and
a voltage regulator coupled to the pump stage selector and configured to provide the voltage regulator signal having a voltage level based at least in part on an output voltage of the charge pump, the voltage regulator including:
a comparator having first and second inputs;
a first resistor divider coupled to the output of the charge pump, the first resistor divider having a first resistor ratio and configured to provide a first resistor divider voltage to the first input of the comparator; and
a second resistor divider configured to be coupled to a voltage supply, the second resistor divider circuit having a second resistor ratio and configured to provide a second resistor divider voltage to the second input of the comparator, the second resistor divider voltage further provided to the pump stage selector as the voltage regulator signal.
17. The charge pump of claim 16 , wherein the first and second resistor ratios are equal.
18. The charge pump of claim 16 , wherein the first resistor divider comprises a variable resistor.
19. The charge pump of claim 16 , wherein the second resistor divider is further coupled to a reference voltage generator.
20. The charge pump of claim 16 , wherein the second resistor divider voltage is provided to the pump stage selector and the pump stage selector is configured to control configuration of first, second, and third charge pump stages based at least in part on the second resistor divider voltage.
21. The charge pump of claim 20 , wherein the pump stage selector is configured to compare the second resistor divider voltage to a reference voltage to configure the first, second, and third charge pump stages, the reference voltage based at least in part on a supply voltage.