Disclosed is a multi-stage charge pump. A first stage is controlled by a first clock signal. A second stage is controlled by a second clock signal, which has high and low states that are shifted relative to the high and low states of the first clock signal. The high and low states of the second clock signal can be higher than the high and low states, respectively, of the first clock signal for a positive charge pump and vice versa for a negative charge pump. Any additional stage is similarly controlled by an additional clock signal that is shifted with respect to the clock signal controlling the immediately preceding stage. By shifting the high and low states of clock signals controlling downstream stages, the need for series-connected or high voltage capacitors in the downstream stages is eliminated and circuit complexity and area consumption are reduced.

A multi-level converter comprises one or more flying capacitors configured to operate at balanced voltages. The multi-level converter comprises a plurality of switching groups comprising pairs of switches operable to transfer energy to and from an inductor and the one or more flying capacitors for inverting an input voltage to an inverted output voltage. The multi-level converter comprises the inductor configured to operate according to an inductor frequency greater than a switching frequency used to control the plurality of switching groups.

This application relates to methods and apparatus for driving a transducer with switching drivers. A switching driver has first and second supply node for receiving supply voltages and includes an output bridge stage, a capacitor and a network of switches. The network of switches is operable in different switch states to provide different switching voltages to the output bridge stage. A controller is configured to control the switch state of the network of switches and a duty cycle of output switches of the output bridge stage based on an input signal to generate an output signal for driving the transducer.

An apparatus includes a DC-to-AC converter comprising a first output terminal and a second output terminal. The apparatus also includes a DC-to-DC converter comprising a third output. The DC-to-AC converter is configured to receive a DC input voltage from a DC power source, and to produce a first alternating output voltage at the first output terminal, and a second alternating output voltage at the second output terminal. The DC-to-DC converter is configured receive a DC input voltage from the DC power source, and to step down the DC input voltage at the third output.

A switch activation system including a charge pump, a load monitor, and a switch driver. The charge pump drives a negative voltage node to a predetermined negative voltage level. The load monitor monitors the charge pump and to assert a break done signal after the charge pump begins driving the negative voltage back to the predetermined negative voltage level after being increased. The switch driver turns on a first electronic switch in response to assertion of a corresponding activation signal and assertion of the break done signal. The break done signal is asserted only after electronic switches being turned off are fully turned off to avoid conflict. The charge pump operates at a frequency based on a difference between a voltage level of the negative voltage node and the predetermined negative voltage level to drive the negative voltage node back to its predetermined level within a predetermined period of time.

A voltage supply circuit and a method for controlling a voltage supply circuit are provided. The voltage supply circuit includes a positive charge pump stage that generates a positive voltage and a negative charge pump stage that generates a negative voltage. The voltage supply circuit also includes a control stage that compares a voltage representative of the negative voltage with a reference voltage and causes a slope of the positive voltage to decrease when the voltage representative of the negative voltage exceeds the reference voltage.

A power supply device includes a switching converter, an inductor, and a linear voltage regulator. The inductor is electrically connected between a first switching node and a second switching node of the switching converter. The power supply device is configured such that when the switching converter is in an ON state the inductor is charged with a charging current. The power supply device is further configured such that when the switching converter is in an OFF state, the switching converter modulates an input voltage to generate a positive-bias output voltage at a positive-bias output node, the charging current flows from the inductor such that a negative input voltage is generated at a linear voltage regulator input node, and the linear voltage regulator regulates the negative input voltage to generate a negative-bias output voltage at a negative-bias output node.

Charging and discharging circuits for assisting charge pumps are disclosed. In certain embodiments, a radio frequency (RF) switch system includes an RF switch that receives an RF signal and is controlled by a switch control signal received at an input, a first charge pump configured to generate a first charge pump voltage, a level shifter powered by the first charge pump voltage and that generates the switch control signal based on a switch enable signal, and a charge pump assistance switch coupled to the input of the radio frequency switch and that activates to assist the first charge pump in response to a transition of the switch enable signal from a first state to a second state.

A DC-DC converter including voltage and slope regulation and a method of operating the same are provided. Generally, the converter includes a voltage source to supply an output, a switching-circuit coupled to the voltage sources to control a voltage on the output, and a slope-detector coupled to the switching-circuit and the output to detect a slope of a voltage transition between a first and a second voltage. When the detected slope exceeds a predetermined maximum the slope-detector sends a digital signal to the switching-circuit to intermittently pause the voltage transition to limit the slope to less than the maximum. In one embodiment, the voltage source is a charge-pump, and the switching-circuit includes a logic-gate coupled to the slope-detector to turn the charge-pump ON when the detected slope is less than the maximum, and to turn OFF the charge-pump for a time when the slope exceeds the maximum.

A motion sensing system uses high-voltage biasing to achieve high resolution with ultra-low power. The motion sensing system consists of a motion sensor, a readout circuit, and a high-voltage bias circuit to generate the optimized bias voltage for the motion sensor. By using the high-voltage bias, the signal from the motion sensor is raised above the readout circuit's noise floor, eliminating the power-hungry amplifier and signal-chopping used in conventional motion sensing systems. The bias circuit, while producing the programmable bias voltages for the motion sensor, also compensates for the process mismatch raised by the high voltage biases.