High voltage driver using medium voltage devices

• US 9,252,651 B2
• Filed: 06/20/2012
• Issued: 02/02/2016
• Est. Priority Date: 06/29/2011
• Status: Active Grant

• Current Assignee: Omnivision TDDI Ontario Limited Partnership
• Original Assignee: Synaptics Incorporated
• Inventors: Mott, Brian, Knausz, Imre
• Primary Examiner(s): Hiltunen, Thomas J
• Application Number:
  US13/528,324
• Publication Number:
  US 20130002149A1
• Time in Patent Office: 1,322 Days
• US Class Current: 1/1
• CPC Class Codes: H02M 1/088 for the simultaneous control of series or parallel connected semiconductor devices
• CPC Class Codes: H03K 17/102 in field-effect transistor switches
• CPC Class Codes: H03K 17/6872 using complementary field-effect transistors

Abstract

A voltage drive circuit is constructed by stacking NMOS and PMOS transistors to provide high voltage levels with an output voltage swing greater than the breakdown voltage of the individual transistors used to build the voltage drive circuit. The voltage drive circuit may include a series stack of capacitors connected between gates of the stacked PMOS and NMOS transistors. The capacitive loading causes the gate signals to change more synchronously. Errors in timing for these gate signals, which would otherwise result in damage from exceeding the breakdown voltage across a pair of terminals of one of the NMOS and PMOS transistors, are mollified.

Claims

1. A voltage drive circuit, comprising:

a first plurality of transistors connected in series between a first source node and an output node;

a plurality of voltage sources configured to provide a voltage to at least one of the first plurality of transistors; and

a plurality of capacitors coupled across gates of the first plurality of transistors, each capacitor configured to store charges associated with changes at gates of the transistors, wherein the plurality of capacitors have capacitances selected to synchronize voltage changes at the first plurality of transistors,

wherein the voltage drive circuit is configured to transition from a first steady state that provides a first voltage to a second steady state that provides a second voltage;

wherein the plurality of capacitors are configured to store charges while transitioning from the first steady state to the second steady state; and

wherein a difference between the first and second voltages is greater than a breakdown voltage of each of the first plurality of transistors.

2. The voltage drive circuit of claim 1, wherein each of the plurality of voltage sources is configured to switch and maintain a voltage at a gate of at least one of the first plurality of transistors.

3. The voltage drive circuit of claim 1, further comprising:

a second plurality of transistors in series between a second source node and the output node.

4. The voltage drive circuit of claim 3, wherein the first plurality of transistors in series comprises a plurality of PMOS transistors;

wherein the second plurality of transistors in series comprises a plurality of NMOS transistors;

wherein transistors of the first and second plurality of transistors are arranged such that a drain of each of the transistors is connected with a source of a next one of the transistors; and

wherein a drain of a last one of the PMOS transistors and drain of a last one of the NMOS transistors is connected to the output node.

5. The voltage drive circuit of claim 1, wherein the first plurality of transistors connected in series are connected such that a drain of one of the transistors is connected with a source of a next one of the transistors;

and wherein each one of the capacitors is connected between a gate of one of the transistors and a gate of the next one of the transistors.

6. The voltage drive circuit of claim 5, wherein each of the plurality of capacitors has a capacitance greater than a capacitance of a next capacitor connected between a gate of the next one of the transistors and a gate of a subsequent next one of the transistors.

7. The voltage drive circuit of claim 5, wherein each of the plurality of capacitors has a capacitance that is a multiple of capacitance C, capacitance C being a capacitance of a last one of the capacitors connected between a gate of a penultimate one of the transistors and a gate of a last one of the transistors.

8. A display device, comprising:

voltage drive circuitry configured to provide a first voltage, the voltage drive circuitry comprising;

a first plurality of transistors connected in series between a first source node and an output node;

a plurality of voltage sources configured to provide a voltage to at least one of the first plurality of transistors, wherein each voltage source is configured to switch and maintain a voltage at a gate of at least one of the first plurality of transistors;

a plurality of capacitors coupled across gates of the first plurality of transistors, each capacitor configured to store charges associated with changes at gates of the transistors, wherein the plurality of capacitors have capacitances selected to synchronize voltage changes at the first plurality of transistors; and

at least one weak level shifter connected to at least one of the plurality of capacitors and configured to hold the connected capacitor from discharging; and

a processing system coupled to the voltage drive circuitry and configured to transmit a first logic signal to the voltage drive circuitry corresponding to the first voltage.

9. The display device of claim 8, wherein the voltage drive circuit is configured to transition from a first steady state that provides the first voltage to a second steady state that provides a second voltage;

wherein the plurality of capacitors are configured to store charges while transitioning from the first steady state to the second steady state; and

wherein a difference between the first and second voltages is greater than an individual breakdown voltage of each of the first plurality of transistors.

10. The display device of claim 8, wherein the voltage drive circuit further comprises:

a second plurality of transistors in series between a second source node and the output node, the second plurality of transistors in series comprising a plurality of NMOS transistors;

wherein the first plurality of transistors in series comprises a plurality of PMOS transistors;

wherein transistors of the first and second plurality of transistors are arranged such that a drain of each of the transistors is connected with a source of a next one of the transistors; and

wherein a drain of a last one of the PMOS transistors and drain of a last one of the NMOS transistors is connected to the output node.

11. The display device of claim 8, wherein the first plurality of transistors connected in series are connected such that a drain of one of the transistors is connected with a source of a next one of the transistors;

and

wherein at least one of the capacitors is connected between gates of each adjacent pair of the first plurality of transistors connected in series.

12. The display device of claim 11, wherein each of the plurality of capacitors has a capacitance that is a multiple of capacitance C, capacitance C being a capacitance of a last one of the capacitors connected between a gate of a penultimate one of the transistors and a gate of a last one of the transistors.

13. A method for providing a high power output, the method comprising:

applying a first source signal to a first source node of a first plurality of transistors connected in series; and

charging a first plurality of capacitors coupled between gates of adjacent transistors of the first plurality of transistors connected in series at a rate operable to synchronize a change in state of the first plurality of transistors, wherein the change in state of the first plurality of transistors comprises a change from a first steady state providing a first voltage to a second steady state providing a second voltage,

wherein the first plurality of capacitors are configured to store charges while transitioning from the first steady state to the second steady state; and

wherein a difference between the first and second voltages is greater than a breakdown voltage of each of the first plurality of transistors.

14. The method of claim 13, further comprising:

applying a second source signal to a second source node of a second plurality of transistors connected in series to common output node with the first plurality of transistors; and

charging a second plurality of capacitors coupled between gates of adjacent transistors of the second plurality of transistors connected in series at a rate operable to synchronize a change in state of the second plurality of transistors.

15. The method of claim 14, wherein the applying the first source signal and the applying the second source signal comprises:

applying a first voltage that exceeds a breakdown voltage of at least one of the first plurality of transistors to the first source node;

applying a second voltage that exceeds a breakdown voltage of at least one of the second plurality of transistors to the second source node; and

outputting a first or second VDC output signal at the common output node in response to the first and second voltages.

16. The method of claim 13,

wherein each of the plurality of transistors has a capacitance selected based on a number of the plurality of transistors and a difference between the first and second voltages.

17. The method of claim 13, wherein the applying the first source signal comprises applying a voltage of 10 VDC to the first source node;

and

wherein a voltage across a source and a drain of each of the first plurality of transistors in series does not exceed 6.6 VDC.

18. The method of claim 13, wherein the charging the plurality of capacitors comprises limiting a voltage across a drain and a source of each of the first plurality of transistors connected in series to less than 6.6 VDC.

19. The method of claim 13, wherein the applying the first source signal comprises applying a voltage that exceeds a breakdown voltage of at least one of the first plurality of transistors to the first source node.