DC-DC converter with resonant gate drive

• US 20030090918A1
• Filed: 11/05/2002
• Published: 05/15/2003
• Est. Priority Date: 11/05/2001
• Status: Active Grant

• Current Assignee: Shakti Systems Inc.
• Original Assignee: Shakti Systems Inc.
• Inventors: Trivedi, Malay, Shenai, Krishna
• Granted Patent: US 6,819,088 B2
• Time in Patent Office: Days
• US Class Current: 363/127
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: H02J 1/08 Three-wire systems; Systems having more than three wires
• CPC Class Codes: H02J 1/082 Plural DC voltage, e.g. DC supply voltage with at least two different DC voltage levels
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02M 1/008 Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators
• CPC Class Codes: H02M 1/088 for the simultaneous control of series or parallel connected semiconductor devices
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A direct current to direct current boost or buck voltage converter in accordance with the invention includes a plurality of switching devices that effect voltage conversion and control current flow direction in the converter. The converter also includes a control circuit for comparing an output voltage of the converter with a reference voltage, where the control circuit produces a comparison signal based on that comparison. A resonant gate-drive circuit, also included in the converter and coupled with the control circuit and the plurality of switching devices, opens and closes the plurality of switches in response to the comparison signal to effect voltage conversion and control current flow direction.

Claims

1. A direct current to direct current voltage buck converter circuit comprising:

a substantially static direct current voltage power supply;

a series synchronous rectifier coupled with the power supply;

an inductive-capacitive output voltage filter coupled with the series synchronous rectifier;

a control circuit coupled with an output terminal of the buck converter;

a voltage reference source coupled with the control circuit, wherein the control circuit compares a reference voltage generated by the voltage reference source with an output voltage generated by the buck converter, and produces a comparison signal based on that comparison; and

a resonant gate-drive circuit coupled with the control circuit and the series synchronous rectifier, wherein the resonant gate-drive circuit controls the series synchronous rectifier based, at least in part, on the signal produced by the control circuit.

2. The buck converter of claim 1, wherein the buck converter is a monolithic buck converter implemented on a single integrated circuit.

3. The buck converter of claim 1, wherein the series synchronous rectifier comprises a p-type field effect transistor (FET) having a source terminal coupled with a positive terminal of the power supply, a drain terminal coupled with the voltage filter and a gate terminal coupled with the resonant gate-drive circuit;

and

a n-type FET having a drain terminal coupled with the drain terminal of the p-type FET, a source terminal coupled with an electrical ground, and a gate terminal coupled with the resonant gate-drive circuit.

4. The buck converter of claim 1, wherein the control circuit comprises a voltage amplifier that compares the voltage reference with the output voltage of the buck converter to produce an indication signal that indicates whether the output voltage of the buck converter is above or below the reference voltage;

and

a PWM circuit coupled with the voltage amplifier so as to be responsive to the indication signal, the PWM circuit, in turn, producing the comparison signal, which is then communicated to the resonant gate-drive circuit and, at least in part, directs operation of the resonant gate-drive circuit.

5. The buck converter of claim 1, wherein the resonant gate-drive circuit comprises:

an inverter circuit;

the inverter circuit having an input terminal coupled with the control circuit and an output terminal coupled with the series synchronous rectifier; and

an inductive-capacitive resonant circuit coupled with, and between, an electrical ground and the output terminal of the inverter circuit, wherein the resonant gate-drive circuit operates the series synchronous rectifier so as to regulate the output voltage generated by the buck converter such that the output voltage approximates the reference voltage generated by the voltage reference source.

6. The buck converter of claim 5, wherein the resonant gate-drive circuit further comprises:

a buffer circuit for receiving and amplifying the signal produced by the control circuit; and

a timer circuit coupled with the buffer circuit and the inverter circuit so as to control a pull-up device and pull-down device of the inverter, such that, in operation, the pull-up device and the pull-down device are not in a conduction state simultaneously, wherein the inverter circuit is coupled with the control circuit via the buffer circuit and the timer circuit.

7. The buck converter of claim 6, wherein the timer circuit comprises multiple circuit paths each including one or more delay elements, such that a signal communicated to an input terminal of the timer reaches the end of each of the multiple circuit paths at different times.

8. The buck converter of claim 7, wherein at least one circuit path has a first delay for a low to high transition and a second delay for a high to low transition, wherein the second delay is longer than the first delay.

9. The buck converter of claim 1, wherein the resonant gate-drive circuit further comprises:

a buffer circuit for receiving and amplifying the signal produced by the control circuit;

plural timer circuits coupled with the buffer circuit;

first and second inverter circuits each having;

an input terminal coupled with a respective timer circuit so as to control a pull-up device and pull-down device of each inverter circuit such that, in operation, the respective pull-up device and pull-down devices are not in a conduction state simultaneously; and

an output terminal coupled with the series synchronous rectifier; and

respective inductive-capacitive resonant circuits each coupled with, and between, an electrical ground and respective output terminals of the inverter circuits, wherein respective output terminals of the inverter circuits are coupled with the series synchronous rectifier so as to regulate the output voltage generated by the buck converter such that the output voltage approximates the reference voltage generated by the voltage reference source.

10. The buck converter of claim 1, wherein the resonant gate-drive circuit further comprises:

a buffer circuit for receiving and amplifying the signal produced by the control circuit; and

a timer circuit coupled with the buffer circuit;

first and second inverter circuits each having an input terminal coupled with the timer circuit and an output terminal coupled with the series synchronous rectifier, each being coupled with the timer circuit so as to control a pull-up device and pull-down device of each inverter circuit such that, in operation, the respective pull-up device and pull-down devices are not in a conduction state simultaneously;

respective inductive-capacitive resonant circuits each coupled with, and between, an electrical ground and the output terminal of the inverter circuits;

wherein respective output terminals of the inverter circuits are coupled with the series synchronous rectifier so as to regulate the output voltage generated by the buck converter such that the output voltage approximates the reference voltage generated by the voltage reference source.

11. A direct current to direct current voltage converter comprising:

a plurality of switching devices for effecting voltage conversion and controlling current flow direction in the converter;

a control circuit for comparing an output voltage of the converter with a reference voltage, wherein the control circuit produces a comparison signal based on the comparison of the output voltage and the reference voltage; and

a resonant gate-drive circuit coupled with the control circuit and the plurality of switching devices, wherein the resonant gate-drive circuit opens and closes the plurality of switches in response to the comparison signal to effect voltage conversion and control current flow direction.

12. The voltage converter of claim 11, wherein the plurality of switching devices comprise field effect transistors (FETs) and the resonant gate-drive circuit provides a current source for charging gates of the FETs and a current sink for discharging the gates of the FETs.

13. The voltage converter of claim 11, wherein the voltage converter comprises a buck converter.

14. The voltage converter of claim 11, wherein the voltage converter comprises a boost converter.

15. A direct current to direct current voltage buck converter comprising:

an inductive-capacitive output voltage filter; and

a series synchronous rectifier coupled with the output voltage filter, wherein the rectifier comprises a first switching device and a second switching device, which, in operation, are opened and closed by a resonant gate-drive circuit having respective first and second inductive-capacitive drive circuits, such that the first and second switching devices operate substantially out of phase with respect to each other.

16. The buck converter of claim 15, wherein the buck converter is a monolithic buck converter implemented on a single integrated circuit.

17. The buck converter of claim 16, wherein the first and second switching devices comprise field effect transistors, and the capacitive element of the first and second drive circuits comprise respective gate capacitances of the first and second switching devices.

18. The buck converter of claim 15, wherein the first switching device comprises a p-type field effect transistor, which is coupled with the voltage source and the output voltage filter;

and

the second switching device comprises an n-type field effect transistor, which is coupled with the first switching device, the output voltage filter and an electrical ground.

19. The buck converter of claim 15, further comprising a control circuit coupled with the output voltage filter, a third switching element and a fourth switching element, wherein the third and fourth switching elements are coupled with, respectively, the first and second drive circuits, such that closing the third and fourth switching elements activates its respective drive circuit.

20. The buck converter of claim 19, wherein the control circuit opens and closes the third and fourth switching elements based, at least in part, on an output voltage potential present on the output voltage filter, and respective resonant frequencies of the first and second drive circuits.