Full-Wave Charge Pump With Low-Voltage Startup

• US 20170155379A1
• Filed: 11/30/2016
• Published: 06/01/2017
• Est. Priority Date: 11/30/2015
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: PETERSON, Rebecca L., NAJAFI, Khalil, MCCULLAGH, James John
• Granted Patent: US 10,250,235 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 7/217 using semiconductor devices only

Abstract

A charge pump with low-voltage startup is presented. The charge pump circuit is comprised of transistor pairs arranged in stages, where the charge pump circuit is configured to receive an input voltage and generate an output voltage whose magnitude is larger than magnitude of the input voltage. An energy storage device is configured to receive and store voltage from the charge pump circuit. A switching circuit is interfaced with the control terminals of the transistors in the charge pump circuit. In response to leakage current through the transistors in the charge pump circuit, the switching circuit switches on select transistors in the charge pump circuit while voltage stored by the energy storage device is below threshold voltage of the transistors in the charge pump circuit.

Claims

1. A charge pump, comprising:

a charge pump circuit comprised of transistor pairs arranged in stages, wherein the charge pump circuit is configured to receive an input voltage and generate a DC output voltage whose magnitude is larger than magnitude of the input voltage;

an energy storage device configured to receive and store voltage from the charge pump circuit, where the energy storage device allows current flow such that turn-on voltage of the transistors in the charge pump circuit is not reduced significantly; and

a switching circuit interfaced with control terminals of the transistors in the charge pump circuit and, in response to leakage current through the transistors in the charge pump circuit resulting from an input voltage to the charge pump circuit, switches on and off the transistors in the charge pump circuit while voltage stored by the energy storage device is below the threshold voltage of the transistors in the charge pump circuit.

2. The charge pump of claim 1 wherein the switching circuit is powered by voltage stored by the energy storage device while the voltage stored by the energy storage device is above the threshold voltage of the transistors in the charge pump circuit.

3. The charge pump of claim 1 wherein the charge pump circuit has a Cockcroft-Walton arrangement.

4. The charge pump claim 1 wherein the energy storage component is further defined as a capacitor.

5. The charge pump of claim 1 further comprises a vibrational source of power, wherein the input voltage for the charge pump circuit is received from the vibrational source of power.

6. The charge pump of claim 1 wherein the switching circuit includes a comparator and two or more inverters arranged in series at an output of the comparator, wherein the output of the comparator drives the transistors in the charge pump circuit through the two or more inverters.

7. The charge pump of claim 6 wherein the stages of the charge pump circuit successively increase voltage across the stages and the comparator is configured to receive and compare an input to a lowest voltage stage of the charge pump circuit with an output of the lowest voltage stage of the charge pump circuit.

8. The charge pump of claim 7 further comprises a resistor is coupled in parallel with a capacitor and the resistor and the capacitor are coupled directly to the output of the lowest voltage stage of the charge pump circuit.

9. The charge pump of claim 1 further comprises a mode selector interposed between the energy storage component and the charge pump circuit, wherein the mode selector prevents current flow to the energy storage component while the DC output voltage of the charge pump circuit is below the threshold voltage of the transistors in the charge pump circuit and permits current flow to the energy storage component while the DC output voltage of the charge pump circuit is above the threshold voltage of the transistors in the charge pump circuit.

10. The charge pump of claim 1 further comprises a mode selector interposed between the energy storage component and the charge pump circuit and configured to receive the output voltage from the charge pump circuit, wherein the mode selector passes current from the charge pump circuit to the energy storage component when magnitude of the output voltage exceeds a specific value and blocks the current from the charge pump circuit to the energy storage component when magnitude of the output voltage is below the specific value.

11. A full-wave charge pump, comprising:

a charge pump circuit having a plurality of stages with a Cockcroft-Walton arrangement comprised of transistor pairs arranged in stages;

an energy storage device configured to receive and store an output voltage from the charge pump circuit, where the energy storage device allows current flow such that turn-on voltage of the transistors in the charge pump circuit is not reduced significantly; and

a switching circuit interfaced with control terminals of the transistors in the charge pump circuit and, in response to leakage current through the transistors in the charge pump circuit, switches on and off the transistors in the charge pump circuit while voltage stored by the energy storage device is below threshold voltage of the transistors in the charge pump circuit

wherein the switching circuit is powered by voltage stored by the energy storage device and switches on and off the transistors in the charge pump circuit while the voltage stored by the energy storage device is above the threshold voltage of the transistors in the charge pump circuit.

12. The full-wave charge pump of claim 11 wherein the charge pump circuit is comprised of two half-wave charge pumps electrically coupled together, such that output of one half-wave charge pump is a DC reference voltage for the other half-wave charge pump.

13. The full-wave charge pump of claim 12 wherein the switching circuit includes a first comparator configured to receive and compare an input to a stage having lowest voltage of the charge pump circuit with an output of the stage having the lowest voltage of the charge pump circuit, and a second comparator configured to receive and compare an input to the stage having lowest voltage of the charge pump circuit with ground.

14. The full-wave charge pump of claim 13 wherein the switching circuit further includes a first string of inverters coupled between an output of the first comparator and select control terminals of the transistors, and a second string of inverters coupled between an output of the second comparator and select control terminals of the transistors.

15. The full-wave charge pump of claim 14 further comprises a resistor-capacitor circuit electrically coupled between the output of the stage having the lowest voltage of the charge pump circuit.

16. The full-wave charge pump of claim 15 further comprises a mode selector interposed between the energy storage component and the charge pump circuit, wherein the mode selector prevents current flow to the energy storage component while the DC output voltage of the charge pump circuit is below a specific voltage and permits current flow to the energy storage component while the DC output voltage of the charge pump circuit is above the specific voltage.

17. The full-wave charge pump of claim 11 wherein the energy storage component is further defined as a capacitor having capacitance of 100 microfarads.

18. The full-wave charge pump of claim 11 further comprises a vibrational source of power, wherein the input voltage for the charge pump circuit is received from the vibrational source of power.