Flip voltage follower low dropout regulator

• US 10,429,868 B2
• Filed: 10/29/2018
• Issued: 10/01/2019
• Est. Priority Date: 12/01/2017
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Elhebeary, Mahmoud Mohamed Rashad Ibrahim, Wadhwa, Sameer
• Primary Examiner(s): Tran, Nguyen
• Application Number:
  US16/172,907
• Publication Number:
  US 20190171243A1
• Time in Patent Office: 337 Days
• Field of Search: 323226, 323269, 323270, 323273-281, 327108-112
• CPC Class Codes: G05F 1/468 characterised by reference voltage circuitry, e.g. soft start, remote shutdown
• CPC Class Codes: G05F 1/565 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 Class Codes: G05F 1/575 characterised by the feedback circuit
• CPC Class Codes: G05F 1/59 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 1/088 for the simultaneous control of series or parallel connected semiconductor devices

Abstract

A wide-tuning range low output impedance flip voltage follower (FVF) low dropout regulator (LDO) for large capacitor switching loads is disclosed. In some implementations, a touch sensing controller driver includes the LDO, which has an operational amplifier and a FVF. The FVF can have a gain device, a source follower device, and an adaptive level shifter coupled between a drain of the source follower device and a gate of the gain device.

Claims

1. A touch sensing controller driver, comprising:

a plurality of switches, each of the plurality of switches configured to couple to a signal line of a touch panel;

a signal driver having an upper low dropout regulator (LDO) and a lower LDO, the upper LDO coupled to the plurality of switches to supply a current to the plurality of switches, the lower LDO coupled to the plurality of switches to sink the current from the plurality of switches, wherein the lower LDO comprises;

a lower operational amplifier having an output, a positive input, and a negative input; and

a lower flip voltage follower (FVF) having a lower gain device, a lower source follower device, and a lower adaptive level shifter connected to a drain of the lower source follower device and a gate of the lower gain device, wherein the output of the lower operational amplifier is configured to determine a voltage at a gate of the lower source follower device.

2. The touch sensing controller driver of claim 1, wherein a drain of the lower gain device is coupled to the negative input of the lower operational amplifier.

3. The touch sensing controller driver of claim 1, wherein the lower adaptive level shifter comprises:

a first diode-connected pMOS transistor coupled between the drain of the lower source follower device and the gate of the lower gain device;

a lower compensation capacitor coupled between the drain of the lower source follower device and the gate of the lower gain device; and

a second diode-connected nMOS transistor coupled between the gate of the lower gain device and Vss.

4. The touch sensing controller driver of claim 1, wherein the upper LDO comprises:

an upper operational amplifier having an output, a positive input, and a negative input; and

an upper flip voltage follower (FVF) having an upper gain device, an upper source follower device, and an upper adaptive level shifter coupled between a drain of the upper source follower device and a gate of the upper gain device.

5. The touch sensing controller driver of claim 4, wherein a gate of the upper source follower device is coupled to the output of the upper operational amplifier and a drain of the upper gain device is coupled to the positive input of the upper operational amplifier.

6. The touch sensing controller driver of claim 4, wherein the upper level shifter comprises:

a first diode-connected nMOS transistor coupled between the drain of the upper source follower device and the gate of the upper gain device;

an upper compensation capacitor coupled between the drain of the upper source follower device and the gate of the upper gain device; and

a second diode-connected pMOS transistor coupled between the gate of the upper gain device and Vdd.

7. The touch sensing controller driver of claim 1, wherein the lower LDO further comprises a plurality of lower replica FVFs.

8. The touch sensing controller driver of claim 7, wherein each of the plurality of lower replica FVFs comprises a lower replica adaptive level shifter.

9. The touch sensing controller driver of claim 8, wherein the lower replica adaptive level shifter comprises a first diode-connected pMOS transistor, a second diode-connected nMOS transistor, and a lower compensation capacitor.

10. The touch sensing controller driver of claim 4, wherein the upper LDO further comprises a plurality of upper replica FVFs.

11. The touch sensing controller driver of claim 10, wherein each of the plurality of upper replica FVFs comprises an upper replica adaptive level shifter.

12. The touch sensing controller driver of claim 11, wherein the upper replica adaptive level shifter comprises a first diode-connected pMOS transistor, a second diode connected nMOS transistor, and an upper compensation capacitor.

13. An electronic system, comprising:

a touch sensing panel; and

a touch sensing controller driver coupled to the touch sensing panel, the touch sensing controller driver comprising;

a plurality of switches, each of the plurality of switches configured to couple to a signal line of a touch panel; and

a signal driver having an upper low dropout regulator (LDO) and a lower LDO, the upper LDO coupled to the plurality of switches to supply a current to the plurality of switches, the lower LDO coupled to the plurality of switches to sink the current from the plurality of switches, wherein the lower LDO comprises;

a lower operational amplifier having an output, a positive input, and a negative input; and

a lower flip voltage follower (FVF) having a lower gain device, a lower source follower device, and a lower adaptive level shifter connected to a drain of the lower source follower device and a gate of the lower gain device, wherein the output of the lower operational amplifier is configured to determine a voltage at a gate of the lower source follower device.

14. The electronic system of claim 13, wherein a drain of the lower gain device is coupled to the negative input of the lower operational amplifier.

15. The electronic system of claim 13, wherein the lower adaptive level shifter comprises:

a first diode-connected pMOS transistor coupled between the drain of the lower source follower device and the gate of the lower gain device;

a lower compensation capacitor coupled between the drain of the lower source follower device and the gate of the lower gain device; and

a second diode-connected nMOS transistor coupled between the gate of the lower gain device and Vss.

16. The electronic system of claim 13, wherein the upper LDO comprises:

an upper operational amplifier having an output, a positive input, and a negative input; and

an upper flip voltage follower (FVF) having an upper gain device, an upper source follower device, and an upper adaptive level shifter coupled between a drain of the upper source follower device and a gate of the upper gain device.

17. The electronic system of claim 16, wherein a gate of the upper source follower device is coupled to the output of the upper operational amplifier and a drain of the upper gain device is coupled to the positive input of the upper operational amplifier.

18. The electronic system of claim 16, wherein the upper level shifter comprises:

a first diode-connected nMOS transistor coupled between the drain of the upper source follower device and the gate of the upper gain device;

an upper compensation capacitor coupled between the drain of the upper source follower device and the gate of the upper gain device; and

a second diode-connected pMOS transistor coupled between the gate of the upper gain device and Vdd.

19. The electronic system of claim 13, wherein the lower LDO further comprises a plurality of lower replica FVFs.