Low noise charge pump method and apparatus

Charge pump apparatus for generating an output voltage supply within a circuit, comprising:

• a) a transfer capacitor;
• b) a plurality of transfer capacitor coupling switches, each switchable between a conducting state and a nonconducting state under control of at least one charge pump clock output;
• and
• c) a charge pump clock generating circuit including a ring oscillator comprising an odd number of not more than three inverting driver sections cascaded sequentially in a ring such that each driver section has an output coupled to a next driver section input, wherein a first driver section is next after a last driver section and one of the driver section outputs constitutes a particular charge pump clock output controlling at least one of the transfer capacitor coupling switches, and wherein each driver section includes
• i) circuitry configured as an active current limit to limit a rate of rise of voltage at the driver section output, and
• ii) circuitry configured as an active current limit to limit a rate of fall of voltage at the driver section output;
• d) wherein the plurality of transfer capacitor coupling switches are coupled to the transfer capacitor, and are controlled so as to couple the transfer capacitor to a voltage source during periodic first times, and to couple the transfer capacitor to the output voltage supply during periodic second times that are not concurrent with the first times,
• further comprising a capacitive coupling circuit configured to couple the particular charge pump clock output as a signal to the at least one transfer capacitor coupling switch without increasing a rate of voltage rise or fall of the signal.

Charge pump apparatus for generating an output voltage supply within a circuit, comprising:

• a) a transfer capacitor;
• b) a plurality of transfer capacitor coupling switches, each switchable between a conducting state and a nonconducting state under control of at least one charge pump clock output;
• and
• c) a charge pump clock generating circuit including a ring oscillator comprising an odd number of not more than three inverting driver sections cascaded sequentially in a ring such that each driver section has an output coupled to a next driver section input, wherein a first driver section is next after a last driver section and one of the driver section outputs constitutes a particular charge pump clock output controlling at least one of the transfer capacitor coupling switches, and wherein each driver section includes
• i) circuitry configured as an active current limit to limit a rate of rise of voltage at the driver section output, and
• ii) circuitry configured as an active current limit to limit a rate of fall of voltage at the driver section output;
• d) wherein the plurality of transfer capacitor coupling switches are coupled to the transfer capacitor, and are controlled so as to couple the transfer capacitor to a voltage source during periodic first times, and to couple the transfer capacitor to the output voltage supply during periodic second times that are not concurrent with the first times,
• further comprising a capacitive coupling circuit configured to couple one of the at least one charge pump clock outputs to a control node of one of the plurality of transfer capacitor coupling switches.

Charge pump apparatus for generating an output voltage supply within a circuit, comprising:

• a) a transfer capacitor;
• b) a plurality of transfer capacitor coupling switches, each switchable between a conducting state and a nonconducting state under control of at least one charge pump clock output;
• and
• c) a charge pump clock generating circuit including a ring oscillator comprising an odd number of not more than three inverting driver sections cascaded sequentially in a ring such that each driver section has an output coupled to a next driver section input, wherein a first driver section is next after a last driver section and one of the driver section outputs constitutes a particular charge pump clock output controlling at least one of the transfer capacitor coupling switches, and wherein each driver section includes
• i) circuitry configured as an active current limit to limit a rate of rise of voltage at the driver section output, and
• ii) circuitry configured as an active current limit to limit a rate of fall of voltage at the driver section output;
• d) wherein the plurality of transfer capacitor coupling switches are coupled to the transfer capacitor, and are controlled so as to couple the transfer capacitor to a voltage source during periodic first times, and to couple the transfer capacitor to the output voltage supply during periodic second times that are not concurrent with the first times,
• further comprising corresponding capacitive coupling circuits to couple a control node of each of the plurality of transfer capacitor coupling switches to the particular charge pump clock output.

Charge pump apparatus for generating an output voltage supply within a circuit, comprising:

• a) a transfer capacitor;
• b) a plurality of transfer capacitor coupling switches, each switchable between a conducting state and a nonconducting state under control of at least one charge pump clock output;
• and
• c) a charge pump clock generating circuit including a ring oscillator comprising an odd number of not more than three inverting driver sections cascaded sequentially in a ring such that each driver section has an output coupled to a next driver section input, wherein a first driver section is next after a last driver section and one of the driver section outputs constitutes a particular charge pump clock output controlling at least one of the transfer capacitor coupling switches, and wherein each driver section includes
• i) circuitry configured as an active current limit to limit a rate of rise of voltage at the driver section output, and
• ii) circuitry configured as an active current limit to limit a rate of fall of voltage at the driver section output;
• d) wherein the plurality of transfer capacitor coupling switches are coupled to the transfer capacitor, and are controlled so as to couple the transfer capacitor to a voltage source during periodic first times, and to couple the transfer capacitor to the output voltage supply during periodic second times that are not concurrent with the first times,
• further comprising capacitively coupling substantial charge into the transfer capacitor via the charge pump clock output.

Charge pump apparatus for generating an output voltage supply within a circuit, comprising:

• a) a transfer capacitor;
• b) a plurality of transfer capacitor coupling switches, each switchable between a conducting state and a nonconducting state under control of a charge pump clock output and including
• i) a common discharge switch disposed between a terminal of the transfer capacitor and a common reference connection of the output voltage supply, and having a first control node AC impedance, and
• ii) an output supply discharge switch disposed between an opposite terminal of the transfer capacitor and a connection of the output voltage supply opposite the common reference connection, and having a second control node AC impedance at least twice the first control node AC impedance;
• and
• c) a charge pump clock generating circuit including
• i) circuitry configured to limit a rate of rise of the charge pump clock output, and
• ii) circuitry configured to limit a rate of fall of the charge pump clock output;
• d) wherein the transfer capacitor coupling switches are coupled to the transfer capacitor, and are controlled so as to couple the transfer capacitor to a voltage source during periodic first times, and to couple the transfer capacitor to the output voltage supply during periodic second times that are not concurrent with the first times.

Charge pump apparatus within a monolithic integrated circuit for generating an output voltage supply, comprising:

• a) a transfer capacitor coupled alternately between source connections and output connections;
• b) a plurality of active switches, each switchable between a conducting state and a nonconducting state under control of at least one charge pump clock output to couple charge, which is not substantially conducted by the charge pump clock output, from the source connections to the output connections;
• c) a charge pump clock generating circuit including an active driver circuit configured to both source current to and sink current from the charge pump clock output to cause a voltage waveform of the charge pump clock output to be substantially sine-like due to
• i) circuitry configured to limit source current provided by the active driver circuit to the charge pump clock output, and
• ii) circuitry configured to limit current sunk from the charge pump clock output by the active driver circuit,
• further comprising one or more capacitive coupling networks configured to couple one of the at least one charge pump clock outputs to a control node of at least one of the plurality of active switches, wherein the capacitive coupling necessitates the charge pump clock output to be substantially sine-like.

Charge pump apparatus for generating an output voltage supply within a monolithic integrated circuit, comprising:

• a) a transfer capacitor;
• b) one or more source switching devices disposed in series between the transfer capacitor and a voltage source to convey transfer current to the transfer capacitor from the voltage source when conducting;
• c) one or more output switching devices disposed in series between the transfer capacitor and the output voltage supply to convey transfer current from the transfer capacitor to the output voltage supply when conducting;
• and
• d) a charge pump clock generating circuit configured to provide a single-phase charge pump clock output coupled capacitively, without conveying substantial transfer current, to control nodes of each of the source switching devices to cause conduction during charge periods and nonconduction during discharge periods for all of the source switching devices, the charge pump clock output further coupled capacitively, without conveying substantial transfer current, to control nodes of each of the output switching devices to cause nonconduction during the charge periods and conduction during the discharge periods for all of the output switching devices, wherein the charge periods alternate with, and do not overlap, the discharge periods.

Charge pump apparatus for generating an output voltage supply within a circuit, comprising:

• a) a transfer capacitor;
• b) one or more source switching devices disposed in series between the transfer capacitor and a voltage source;
• c) a first output switching device having a first device area disposed between a first terminal of the transfer capacitor and the output voltage supply, and a second output switching device disposed between a common reference connection of the output voltage supply and a second terminal of the transfer capacitor opposite the first terminal of the transfer capacitor, having a second device area that is greater than double the first device area;
• and
• d) a charge pump clock generating circuit configured to provide a single-phase charge pump clock output coupled to all of the source switching devices to cause conduction during charge periods and nonconduction during discharge periods for all of the source switching devices, the charge pump clock output further coupled to all of the output switching devices to cause nonconduction during the charge periods and conduction during the discharge periods for all of the output switching devices.

Charge pump apparatus for generating an output voltage supply within a monolithic integrated circuit, comprising:

• a) a transfer capacitor for conveying charge from a voltage source to the output voltage supply;
• b) one or more source switching devices disposed in series between the transfer capacitor and the voltage source, each having a corresponding control node that is substantially isolated from both the transfer capacitor and the voltage source;
• c) one or more output switching devices disposed in series between the transfer capacitor and the output voltage supply, each having a corresponding control node that is substantially isolated from both the transfer capacitor and the voltage source;
• and
• d) a capacitive coupling circuit coupling a charge pump clock output to one of the control nodes corresponding to a source switching device or to an output switching device.

A method of generating an output supply from a charge pump incorporated within a monolithic integrated circuit by transferring charge from a source voltage to a transfer capacitor (“TC”) alternately with transferring charge from the TC to the output supply, wherein a TC-coupling switch (“TCCS”) circuit is a switching circuit of the charge pump configured to couple the TC to a supply under control of a charge pump clock, the method comprising:

• a) coupling the TC to the output supply during discharge periods via a discharging TCCS circuit under control of a first charge pump clock output;
• and
• b) actively limiting a rate of voltage change of the first charge pump clock output during both positive transitions and negative transitions such that a voltage of the first charge pump clock output is substantially sine-like,
• further comprising capacitively coupling the first charge pump clock output to a control node of a TCCS circuit thereby necessitating that the first charge pump clock output be substantially sine-like.

A method of generating an output supply from a charge pump by transferring charge from a source voltage to a transfer capacitor (“TC”) alternately with transferring charge from the TC to the output supply, wherein a TC-coupling switch (“TCCS”) circuit is a switching circuit of the charge pump configured to couple the TC to a supply under control of a charge pump clock, the method comprising:

• a) coupling the TC to the output supply during discharge periods via a discharging TCCS circuit under control of a first charge pump clock output;
• b) actively limiting a rate of voltage change of the first charge pump clock output during both positive transitions and negative transitions;
• c) coupling a first terminal of the TC to a common reference connection of the output supply via a discharge common TCCS;
• d) coupling a second opposite terminal of the TC to an output supply connection opposite the common reference connection via a discharge output TCCS;
• and
• e) fabricating the discharge output TCCS to have a control node AC impedance at least double a control node AC impedance of the discharge common TCCS.

A method of generating an output supply by alternately transferring charge from a source voltage to a transfer capacitor (“TC”), and from the TC to the output supply, the method comprising:

• a) coupling the TC to the output supply during discharge periods via a discharging switch circuit under control of a first charge pump clock output;
• b) limiting source current provided to each inverting driver output node of a current starved ring oscillator having not more than three inverting driver stages within a first charge pump clock generator circuit by means of a corresponding source current-limiting circuit;
• and
• c) limiting sink current drawn from each of the inverting driver output nodes by means of a corresponding sink current-limiting circuit;
• wherein the inverting driver output node of one of the not more than three inverting driver stages of the first charge pump clock generator circuit is the first charge pump clock output,
• further comprising coupling the first charge pump clock output to a control node of the discharging switch circuit and/or to a control node of a charging switch via a corresponding capacitive coupling circuit.

A method of generating an output supply by alternately transferring charge from a voltage source to a transfer capacitor (“TC”), and from the TC to the output supply, the method comprising:

• a) coupling the TC to the output supply during discharge periods via a plurality of TC discharging switches under control of a single phase charge pump clock output;
• b) coupling the TC to the voltage source via a TC charging switch, during charge periods that nonoverlappingly alternate with the discharge periods, under control of the single-phase charge pump clock output;
• c) coupling a first TC discharging switch in series between a first node of the TC and a common reference connection of the output supply;
• d) coupling a second TC discharging switch in series between a second node of the TC opposite the first node and a connection of the output supply opposite the common reference connection;
• and
• e) fabricating the second TC discharging switch to have a control node AC impedance at least twice as large as a control node AC impedance of the first discharging switch.

A method of generating an output supply within a monolithic integrated circuit by alternately transferring charge from a voltage source to a transfer capacitor (“TC”), and from the TC to the output supply, the method comprising:

• a) coupling the TC to the output supply during discharge periods via a first actively controllable TC discharging switch under control of a single phase charge pump clock output that is capacitively coupled to a control node of the first actively controllable TC discharging switch and substantially isolated from the TC;
• b) coupling the TC to the voltage source via a first actively controllable TC charging switch, during charge periods that nonoverlappingly alternate with the discharge periods, under control of the single-phase charge pump clock output that is capacitively coupled to a control node of the first actively controllable TC charging switch;
• c) coupling a second TC to a second voltage source via a second actively controllable TC charging switch under control of the charge pump clock output;
• and
• d) coupling the second TC to a second output supply via a second actively controllable TC discharging switch under control of the charge pump clock output;
• further comprising coupling the charge pump clock output to a control node of each actively controllable TC charging switch, and to each actively controllable TC discharging switch, via corresponding capacitive coupling circuits.

A method of generating an output supply within a monolithic integrated circuit by alternately transferring charge for the output supply from a source voltage to a transfer capacitor (“TC”), and from the TC to the output supply, the method comprising:

• a) coupling a first charge pump clock output to a control node of a TC charging switch via a first capacitive coupling network that does not conduct a significant portion of the charge for the output;
• b) coupling the TC to the source voltage during charge periods via the TC charging switch under control of the first charge pump clock output;
• c) coupling a second charge pump clock output to a control node of a TC discharging switch via a second capacitive coupling network that does not conduct a significant portion of the charge for the output;
• and
• d) coupling the TC to the output supply via the TC discharging switch during discharge periods nonconcurrently alternating with the charge periods under control of the second charge pump clock output.