Negative voltage feedback generator

Patent metadata

Field	Value
Publication number	US-9310817-B2
Application number	US-201414231108-A
Country	US
Kind code	B2
Filing date	Mar 31, 2014
Priority date	Feb 4, 2014
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Embodiments of the invention generally provide an device that regulates a negative output voltage from a power supply using a positive representation of the negative output voltage. To convert the negative voltage to a positive voltage, the device changes the negative voltage into a current using, for example, a current generator that outputs a current corresponding to the negative voltage received from the power supply. This current is then transferred from the negative voltage domain to the positive voltage domain and is fed through a voltage generator that outputs a positive voltage corresponding to the current. By doing so, the negative voltage output is transformed into a corresponding positive voltage. This positive voltage may then be compared to a positive reference voltage to determine an error signal for adjusting the power supply.

First claim

I claim:

1. A voltage conversion circuit comprising:
a voltage-to-current converter configured to receive only a negative voltage in a negative domain as an input and output a current based on a difference between the negative voltage and a constant reference voltage;
a converter configured to receive the output current from the voltage-to-current converter and convert the output current in the negative domain to a transferred current in a positive domain; and
a current-to-voltage converter configured to generate a positive voltage in the positive domain that corresponds to the transferred current.

2. The circuit of claim 1 , further comprising an error compensator coupled to an output of the current-to-voltage converter to receive the positive voltage, the error compensator configured to compare the positive voltage to a positive reference voltage to regulate a negative output voltage from a power supply.

3. The circuit of claim 1 , wherein the voltage-to-current converter comprises an amplifier configured to provide the constant reference voltage based on an input reference voltage.

4. The circuit of claim 3 , wherein the voltage-to-current converter comprises a field-effect transistor in a feedback loop of the amplifier, wherein a source of the field-effect transistor provides the constant reference voltage and a gate of the field-effect transistor is coupled to an output of the amplifier.

5. The circuit of claim 1 , wherein the constant reference voltage is substantially equal to a system ground, wherein the converter comprises a current mirror including at least two transistors, wherein the current mirror is configured such that a shared gate voltage of the at least two transistors is driven to a value that results in a source of one of the at least two transistors to output the system ground as the constant reference voltage.

6. The circuit of claim 1 , wherein the converter comprises a current mirror including at least two transistors, wherein a shared gate voltage whose value is determined by the output current is used by the current mirror to generate the transferred current.

7. The circuit of claim 6 , wherein electrical characteristics of the at least two transistors are selected such that the current mirror is configured to attenuate the output current when generating the transferred current.

8. The circuit of claim 6 , wherein at least one of the at least two transistors is programmable to adapt the circuit to output corresponding positive voltages for different values of the negative voltage.

9. A method comprising:
receiving only a negative voltage in a negative voltage domain at an input of a voltage-to-current converter;
converting the negative voltage into a corresponding current using the voltage-to-current converter based on a difference between the negative voltage and a constant reference voltage;
converting the corresponding current in the negative domain to a transferred current in a positive domain; and
generating a positive voltage in the positive domain that corresponds to the transferred current.

10. The method of claim 9 , further comprising:
regulating a negative output voltage from a power supply using an error voltage determined by comparing the positive voltage to a positive reference voltage.

11. The method of claim 9 , wherein converting the negative voltage into the corresponding current comprises:
generating the constant reference voltage using an amplifier that receives an input reference voltage that controls a value of the constant reference voltage.

12. The method of claim 11 , wherein converting the negative voltage into the corresponding current comprises:
generating the constant reference voltage at a source of a field-effect transistor in a feedback loop of the amplifier, wherein a gate of the transistor is coupled to an output of the amplifier.

13. The method of claim 9 , wherein the constant reference voltage is substantially equal to a system ground, wherein a current mirror including at least two transistors is configured such that a shared gate voltage of the at least two transistors is driven to a value that results in a source of one of the at least two transistors to output the system ground as the constant reference voltage.

14. The method of claim 9 , wherein converting the corresponding current to the transferred current in the positive domain comprises:
generating the transferred current using a shared gate voltage of at least two transistors forming a current mirror, wherein a value of the shared gate voltage is set by the corresponding current.

15. The method of claim 14 , further comprising:
programming at least one of the at least two transistors to configure the current mirror based on different values of the negative voltage.

16. A processing system comprising:
a voltage-to-current converter configured to receive a negative voltage in a negative domain as an input and output a current based on a difference between the negative voltage and a constant reference voltage;
a converter configured to receive the output current from the voltage-to-current converter and convert the output current in the negative domain to a transferred current in a positive domain;
a current-to-voltage converter configured to generate a positive voltage in the positive domain that corresponds to the transferred current; and
an error compensator coupled to an output of the current-to-voltage converter to receive the positive voltage, the error compensator is configured to compare the positive voltage to a positive reference voltage to regulate a supply voltage in the processing system.

17. The processing system of claim 16 , further comprising:
a sensing module configured to control a plurality of sensor electrodes for performing capacitive sensing.

18. The processing system of claim 17 , wherein the sensing module, voltage-to-current converter, converter, current-to-voltage converter, and error compensator are located on a single integrated circuit.

19. The processing system of claim 17 , further comprising:
a display module configured to control a plurality of display electrodes for updating a display.

20. The processing system of claim 19 , wherein the sensing module, display module, voltage-to-current converter, converter, current-to-voltage converter, and error compensator are located on a single integrated circuit.

Assignees

• Synaptics Inc

Inventors

• Pude Mark

Classifications

• G05F1/575

  characterised by the feedback circuit · CPC title

• G05F1/565 Primary

  sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor (G05F1/563 takes precedence) · CPC title

• H02M3/07

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

• G05F3/30

  Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities (G05F3/26 takes precedence) · CPC title