Charge pump generator with direct voltage sensor

Patent metadata

Field	Value
Publication number	US-9250271-B2
Application number	US-201313975904-A
Country	US
Kind code	B2
Filing date	Aug 26, 2013
Priority date	Aug 26, 2013
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

Embodiments relate to a direct voltage sensor and a charge pump system for a computer system. A charge pump that supplies switching current for a plurality of transistors includes a capacitor generating a pumped voltage. A comparator generates a pump control signal for turning on and off charging of the pump capacitor based on a difference between a comparison voltage and a reference voltage. A direct voltage sensor receives a feedback signal reflecting the pumped voltage and generates the comparison voltage in response to the feedback signal. The sensor includes a sensor resistor, a current source configured to drive a sensor current through the sensor resistor, and a differential op-amp that drives the sensor current to cause the voltage drop across the sensor resistor to remain constant as the pumped voltage experiences the voltage drop. The charge pump may include two similar direct voltage sensor controlling positive and negative pumped voltages.

First claim

What is claimed is:

1. A direct voltage sensor for a computer circuit, comprising:
a sensor resistor having a first end and a second end;
a current source having an source input directly connected to the second end of the sensor resistor and a source output, the current source configured to drive a sensor current through the sensor resistor;
a differential op-amp comprising a first input directly connected to the source input of current source and the second end of the sensor resistor, and a second input directly connected to the first end of the sensor resistor, the differential op-amp configured to receive a voltage drop across the sensor resistor caused by the sensor current, the second input connected to a pump voltage source to receive a pumped voltage, wherein the differential op-amp further comprises an output reflecting a difference between voltage levels on the first and second inputs;
a feedback connection from the op-amp output directly to the current source configured to control the current source to drive the sensor current;
wherein the first end of the sensor resistor is configured to receive a feedback signal directly from the pump voltage source included in a charge pump system generating the pumped voltage;
wherein the second end of the sensor resistor is configured to generate a comparison voltage representative of the pumped voltage as the pumped voltage experiences a voltage drop resulting from depletion of electric charge stored by a capacitor of the charge pump; and
wherein the differential op-amp is configured to drive the sensor current to cause the voltage drop across the sensor resistor to remain constant as the pumped voltage experiences the voltage drop.

2. The direct voltage sensor of claim 1 , wherein the pumped voltage is a positive pumped voltage.

3. The direct voltage sensor of claim 1 , wherein the pumped voltage is a negative pumped voltage.

4. The direct voltage sensor of claim 1 , wherein:
the direct voltage sensor is a first direct voltage sensor;
the pumped voltage is a positive pumped voltage;
further comprising a second direct voltage sensor configured to measure a negative pumped voltage.

5. The direct voltage sensor of claim 4 , wherein the first and second direct voltage sensors supply respective comparators that utilize a common reference voltage.

6. The direct voltage sensor of claim 1 , implemented as part of integrated circuit chip without incorporating electronic components external to the chip other than a an external power supply.

7. The direct voltage sensor of claim 6 , wherein the chip comprises a microprocessor.

8. The direct voltage sensor of claim 6 , wherein the chip comprises a memory array.

9. A charge pump system for a computer circuit, comprising:
a charge pump comprising a capacitor generating a pumped voltage for supplying switching current for a plurality of transistors;
a comparator generating a pump control signal for turning on and off charging of the capacitor of the charge pump based on a difference between a comparison voltage and a reference voltage; and
a direct voltage sensor for receiving a feedback signal reflecting the pumped voltage and generating the comparison voltage in response to the feedback signal, comprising:
a sensor resistor having a first end and a second end;
a current source having an source input directly connected to the second end of the sensor resistor and a source output, the current source configured to drive a sensor current through the sensor resistor;
a differential op-amp comprising a first input directly connected to the source input of current source and the second end of the sensor resistor, and a second input directly connected to the first end of the sensor resistor, the differential op-amp configured to receive a voltage drop across the sensor resistor caused by the sensor current, the second input connected to a pump voltage source to receive a pumped voltage, wherein the differential op-amp further comprises an output reflecting a difference between voltage levels on the first and second inputs,
a feedback connection from the differential op-amp output directly to the current source configured to control the current source to drive the sensor current,
wherein the first end of the sensor resistor is configured to receive the feedback signal directly from the pump voltage source included in the charge pump system generating the pumped voltage,
wherein the second end of the sensor resistor is configured to generate the comparison voltage representative of the pumped voltage as the pumped voltage experiences a voltage drop resulting from depletion of electric charge stored by a capacitor of the charge pump, and
wherein the differential op-amp is configured to drive the sensor current to cause the voltage drop across the sensor resistor to remain constant as the pumped voltage experiences the voltage drop.

10. The charge pump system of claim 9 , wherein the pumped voltage is a positive pumped voltage.

11. The charge pump system of claim 9 , wherein the pumped voltage is a negative pumped voltage.

12. The charge pump system of claim 9 , wherein:
the direct voltage sensor is a first direct voltage sensor;
the pumped voltage is a positive pumped voltage;
further comprising a second direct voltage sensor configured to measure a negative pumped voltage.

13. The charge pump system of claim 12 , wherein the first and second direct voltage sensors supply respective comparators that utilize a common reference voltage.

14. The direct voltage sensor of claim 9 , implemented as part of integrated circuit chip without incorporating electronic components external to the chip other than an external power supply.

15. The direct voltage sensor of claim 14 , wherein the chip comprises a microprocessor.

16. The direct voltage sensor of claim 14 , wherein the chip comprises a memory array.

Assignees

• IBM
• Globalfoundries Inc

Inventors

• Muench Paul D
• Plass Donald W
• Sperling Michael A

Classifications

• G05F1/00

  Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems · CPC title

• G01R19/0023 Primary

  Measuring currents or voltages from sources with high internal resistance by means of measuring circuits with high input impedance, e.g. OP-amplifiers (electrostatic instruments G01R5/28; measuring electrostatic potential G01R15/165; measuring electrostatic fields G01R29/12; amplifiers per se H03F) · CPC title

• G06F1/30

  Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations (for resetting only G06F1/24) · CPC title

• G06F1/26

  Power supply means, e.g. regulation thereof (for memories G11C) · CPC title

• H02M3/07

  using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} · CPC title