Low noise charge pumps

1. A front end system comprising:

a radio frequency switch;

a switch controller configured to bias the radio frequency switch with a charge pump voltage in a first state of a switch enable signal; and

a charge pump configured to generate the charge pump voltage at a charge pump output terminal, the charge pump including a switched capacitor, an inverter having an output electrically connected to a first end of the switched capacitor, and a plurality of switches configured to charge the switched capacitor during a charging operation of the charge pump and to connect the switched capacitor to the charge pump output terminal during a discharging operation of the charge pump, the plurality of switches configured to operate with non-overlap between the charging operation and the discharging operation, the plurality of switches including a pair of charging switches connected between a second end of the switched capacitor and a reference voltage and a pair of discharging switches connected between the second end of the switched capacitor and the charge pump output terminal, a first charging switch of the pair of charging switches being controlled by a first clock phase signal, an input of the inverter receiving a second clock phase signal delayed relative to the first clock phase signal, and a second charging switch of the pair of charging switches being controlled by a third clock signal phase delayed relative to the second clock phase signal.

2. The front end system of claim 1 wherein the charge pump is powered by a power high supply voltage and a ground voltage, the charge pump voltage less than the ground voltage.

3. The front end system of claim 1 wherein the pair of charging switches is closed during the charging operation and open during the discharging operation, and the pair of discharging switches is closed during the discharging operation and open during the charging operation.

4. The front end system of claim 1 wherein a first discharging switch of the pair of discharging switches is controlled by an inverted version of the first clock phase signal and a second discharging switch of the pair of discharging switches is controlled by an inverted version of the third clock phase signal.

5. The front end system of claim 1 wherein the charge pump further includes an oscillator configured to generate a first plurality of clock signal phases, and combinatorial logic configured to process the first plurality of clock signal phases to generate a second plurality of clock signal phases, at least a portion of the switches controlled by the second plurality of clock signal phases.

6. The front end system of claim 1 wherein the charge pump includes a plurality of stages including a first stage and a second stage, the first stage including the plurality of switches and the switched capacitor.

7. The front end system of claim 6 wherein the plurality of switches are controlled in part by a clock signal from the second stage.

8. A front end system comprising:

a switch controller configured to bias the radio frequency switch with a charge pump voltage in a first state of a switch enable signal; and

a charge pump configured to generate the charge pump voltage at a charge pump output terminal, the charge pump including a switched capacitor, an inverter having an output electrically connected to a first end of the switched capacitor, and a plurality of switches configured to charge the switched capacitor during a charging operation of the charge pump and to connect the switched capacitor to the charge pump output terminal during a discharging operation of the charge pump, the plurality of switches configured to operate with non-overlap between the charging operation and the discharging operation, the plurality of switches including a pair of charging switches connected between a second end of the switched capacitor and a reference voltage and a pair of discharging switches connected between the second end of the switched capacitor and the charge pump output terminal, the pair of charging switches being closed during the charging operation and open during the discharging operation, and the pair of discharging switches being closed during the discharging operation and open during the charging operation, the pair of charging switches further configured such that during a transition from the charging operation to the discharging operation, one charging switch of the pair of charging switches is open and the other charging switch of the pair of charging switches is closed.

9. The front end system of claim 8 wherein during the transition from the charging operation to the discharging operation, one discharging switch of the pair of discharging switches is open and the other discharging switch of the pair of discharging switches is closed.

10. A method of generating a charge pump voltage, the method comprising:

charging a switched capacitor using a plurality of switches during a charging operation of a charge pump;

transitioning the charge pump from the charging operation to a discharging operation with non-overlap;

connecting the switched capacitor to a charge pump output terminal during the discharging operation;

controlling a first end of the switched capacitor using an output of an inverter and controlling a second end of the switched capacitor using the plurality of switches;

closing a pair of charging switches of the plurality of switches during the charging operation, opening a pair of discharging switches of the plurality of switches during the charging operation, opening the pair of charging switches during the discharging operation, and closing the pair of discharging switches during the discharging operation; and

opening one charging switch of the pair of charging switches and closing the other charging switch of the pair of charging switches during a transition from the charging operation to the discharging operation.

11. The method of claim 10 further comprising opening one discharging switch of the pair of discharging switches and closing the other discharging switch of the pair of discharging switches during a transition from the charging operation to the discharging operation.

12. The method of claim 10 further comprising powering the inverter using a power high supply voltage and a ground voltage, the charge pump voltage less than the ground voltage.

13. The method of claim 10 further comprising closing the pair of charging switches during the charging operation and opening the pair of charging switches during the discharging operation.

14. The method of claim 10 further comprising closing the pair of discharging switches during the discharging operation and opening the pair of discharging switches during the charging operation.

15. The method of claim 10 further comprising generating a first plurality of clock signal phases using an oscillator, generating a second plurality of clock signal phases by processing the first plurality of clock signal phases using combinatorial logic, and controlling at least a portion of the switches using the second plurality of clock signal phases.

16. A charge pump comprising:

a charge pump output terminal configured to provide a charge pump voltage;

a switched capacitor;

an inverter having an output electrically connected to a first end of the switched capacitor; and

a plurality of switches electrically connected to a second end of the switched capacitor and configured to charge the switched capacitor during a charging operation of the charge pump and to connect the switched capacitor to the charge pump output terminal during a discharging operation of the charge pump, the plurality of switches configured to operate with non-overlap between the charging operation and the discharging operation, the plurality of switches including a pair of charging switches closed during the charging operation and open during the discharging operation, and a pair of discharging switches closed during the discharging operation and open during the charging operation, the pair of charging switches configured such that during a transition from the charging operation to the discharging operation, one charging switch of the pair of charging switches is open and the other charging switch of the pair of charging switches is closed.

17. The charge pump of claim 16 wherein the inverter is powered by a power high supply voltage and a ground voltage, the charge pump voltage less than the ground voltage.

18. The charge pump of claim 16 wherein the pair of charging switches is closed during the charging operation and open during the discharging operation.

19. The charge pump of claim 16 wherein the pair of discharging switches is closed during the discharging operation and open during the charging operation.

20. The charge pump of claim 16 further comprising an oscillator configured to generate a first plurality of clock signal phases, and combinatorial logic configured to process the first plurality of clock signal phases to generate a second plurality of clock signal phases, at least a portion of the switches controlled by the second plurality of clock signal phases.