Driver circuit for providing an output signal

• US 7,511,540 B2
• Filed: 03/21/2007
• Issued: 03/31/2009
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Trebo, Heinrich, Dickman, Rory
• Primary Examiner(s): Donovan; Lincoln
• Assistant Examiner(s): O'Neill; Patrick
• Application Number:
  US11/689,163
• Publication Number:
  US 20070285133A1
• Time in Patent Office: 741 Days
• Field of Search: 327108-112, 327/419, 327/427, 327/434, 326 82- 87
• US Class Current: 327/108
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H03K 17/04206 in field-effect transistor switches

Abstract

A driver circuit for providing an output signal for switching an electrical load on and off has a field-effect transistor having a gate terminal and an output for providing the output signal to the electrical load, a buffer circuit connected to the gate terminal of the field-effect transistor to impress a charge change current on the gate terminal of the field-effect transistor based on a drive signal, and a comparator having a first input for receiving the gate voltage and a second input for receiving the output signal to determine whether the gate voltage and the output voltage fulfill a predetermined relationship with respect to each other, and to provide the drive signal to the buffer circuit so that the charge change current is changed in magnitude when the predetermined relationship is fulfilled as compared to the charge change current when the predetermined relationship is not fulfilled.

Claims

1. A driver circuit for providing an output signal for switching an electrical load on and off, comprising:

a field-effect transistor comprising a gate terminal and an output for providing the output signal to the electrical load;

a buffer circuit connected to the gate terminal of the field-effect transistor and formed to impress a charge change current at the gate terminal of the field-effect transistor and based on a drive signal; and

a comparator comprising a first input for receiving a gate voltage of the field-effect transistor and a second input for receiving the output signal,

wherein the comparator is formed to determine whether the gate voltage and the output voltage fulfill a predetermined relationship with respect to each other, and to provide the drive signal to the buffer circuit so that, when the predetermined relationship is fulfilled, the charge change current is changed in magnitude as compared to a charge change current when the predetermined relationship is not fulfilled.

2. The driver circuit according to claim 1, wherein the driver circuit comprises an input for receiving a control signal to effect switching on and/or switching off of the electrical load.

3. The driver circuit according to claim 2, wherein the comparator is formed to provide the drive signal to the buffer circuit when a control signal is applied that effects switching on of the electrical load, and when the predetermined relationship is fulfilled, so that the charge change current at the field-effect transistor increases;

and

to provide the drive signal to the buffer circuit when the control signal is applied which effects the switching off of the electrical load, and when the predetermined relationship is fulfilled, so that the charge change current at the field-effect transistor is reduced.

4. The driver circuit according to claim 1, wherein the buffer circuit comprises a current source, wherein the current source comprises a current mirror circuit with a current mirror input terminal and a current mirror output terminal, wherein the current mirror output terminal is coupled to the gate terminal of the field-effect transistor, wherein the current mirror input terminal is coupled to the comparator to receive the drive signal, wherein the drive signal is a current, and wherein the current mirror circuit is formed to provide a current at the current mirror output terminal that is proportional to a current arriving at the current mirror input terminal.

5. The driver circuit according to claim 4, wherein a reference current is additionally impressed on the current mirror circuit at the current mirror input terminal.

6. The driver circuit according to claim 1, wherein the comparator comprises a third input for receiving an activation signal to allow the comparator to be switched on and off.

7. The driver circuit according to claim 6, wherein the comparator comprises:

a first transistor comprising a first terminal, a second terminal and a control terminal;

a second transistor comprising a first terminal, a second terminal and a control terminal;

a third transistor comprising a first terminal, a second terminal and a control terminal;

a fourth transistor comprising a first terminal, a second terminal and a control terminal; and

a first current source, wherein

the first transistor is coupled to the first input of the comparator with the first terminal, to the control terminal of the second terminal with the second terminal and to the third input of the comparator with the control terminal, wherein the second transistor is coupled to a supply voltage with the first terminal and to the first current source with the second terminal, wherein the third transistor is coupled to a fourth terminal of the comparator with the first terminal, to the first current source with the second terminal and to the second terminal of the fourth transistor with the control terminal, wherein the fourth transistor is coupled to the second input of the comparator with the first terminal and to the third input of the comparator with the control terminal, and wherein the first current source is further connected to a reference potential.

8. The driver circuit according to claim 7, wherein the comparator further comprises a second current source coupled to the reference potential and the second terminal of the first transistor, and a third current source coupled to the reference potential and the second terminal of the fourth transistor.

9. The driver circuit according to claim 8, wherein the comparator further comprises a fourth current source and a first resistor, wherein the fourth current source is coupled to the reference potential and to the control terminal of the third transistor via the first resistor.

10. The driver circuit according to claim 8, wherein the comparator further comprises a second resistor connected between the first terminal of the first transistor and the first input of the comparator, and a third resistor connected between the first terminal of the fourth transistor and the second input of the comparator.

11. The driver circuit according to claim 7, wherein the first transistor, the second transistor, the third transistor or the fourth transistor is a field-effect transistor, so that the first terminal is a drain terminal, the second terminal is a source terminal, and the control terminal is a gate terminal.

12. A method for providing an output signal for switching an electrical load on and off, comprising:

providing a field-effect transistor comprising a gate terminal and an output for providing the output signal to the electrical load;

impressing a charge change current at the gate terminal of the field-effect transistor based on a drive signal by a buffer circuit connected to the gate terminal of the field-effect transistor; and

comparing a gate voltage of the field-effect transistor and the output signal by a comparator to determine whether the gate voltage and the output voltage fulfill a predetermined relationship with respect to each other, and to provide the drive signal to the buffer circuit so that, when the predetermined relationship is fulfilled, the charge change current is changed in magnitude as compared to a charge change current when the predetermined relationship is not fulfilled.

13. The method according to claim 12, further comprising the step of receiving a control signal to effect switching on and/or switching off of the electrical load.

14. The method according to claim 13, wherein the drive signal is fed to the buffer circuit when a control signal is applied that effects switching on of the electrical load, and when the predetermined relationship is fulfilled, so that the charge change current at the field-effect transistor increases;

and

wherein the drive signal is fed to the buffer circuit when the control signal is applied which effects the switching off of the electrical load, and when the predetermined relationship is fulfilled, so that the charge change current at the field-effect transistor is reduced.

15. The method according to claim 12, comprising the step of receiving an activation signal to allow the comparator to be switched on and off.

16. A driver circuit for providing an output signal for switching an electrical load on and off, comprising:

a field-effect transistor comprising a gate terminal and an output for providing the output signal to the electrical load;

a buffer circuit connected to the gate terminal of the field-effect transistor and formed to impress a charge change current at the gate terminal of the field-effect transistor based on a drive signal; and

a comparator comprising a first input for receiving a gate voltage of the field-effect transistor and a second input for receiving the output signal,

wherein the comparator is formed to determine whether the gate voltage and the output voltage fulfill a predetermined relationship with respect to each other, and to provide the drive signal to the buffer circuit so that, when the predetermined relationship is fulfilled, the charge change current is changed in magnitude as compared to a charge change current when the predetermined relationship is not fulfilled,

wherein the driver circuit comprises an input for receiving a control signal to effect switching on and/or switching off of the electrical load,

wherein the comparator is formed to provide the drive signal to the buffer circuit when a control signal is applied that effects switching on of the electrical load, and when the predetermined relationship is fulfilled, so that the charge change current at the field-effect transistor increases, and to provide the drive signal to the buffer circuit when the control signal is applied which effects the switching off of the electrical load, and when the predetermined relationship is fulfilled, so that the charge change current at the field-effect transistor is reduced.

17. The driver circuit according to claim 16, wherein the buffer circuit comprises a current source, wherein the current source comprises a current mirror circuit with a current mirror input terminal and a current mirror output terminal, wherein the current mirror output terminal is coupled to the gate terminal of the field-effect transistor, wherein the current mirror input terminal is coupled to the comparator to receive the drive signal, wherein the drive signal is a current, and wherein the current mirror circuit is formed to provide a current at the current mirror output terminal that is proportional to a current arriving at the current mirror input terminal, wherein a reference current is additionally impressed on the current mirror circuit at the current mirror input terminal.

18. The driver circuit according to claim 16, wherein the comparator comprises a third input for receiving an activation signal to allow the comparator to be switched on and off, wherein the comparator comprises:

a first transistor comprising a first terminal, a second terminal and a control terminal;

a second transistor comprising a first terminal, a second terminal and a control terminal;

a third transistor comprising a first terminal, a second terminal and a control terminal;

a fourth transistor comprising a first terminal, a second terminal and a control terminal; and

a first current source, wherein

the first transistor is coupled to the first input of the comparator with the first terminal, to the control terminal of the second terminal with the second terminal and to the third input of the comparator with the control terminal, wherein the second transistor is coupled to a supply voltage with the first terminal and to the first current source with the second terminal, wherein the third transistor is coupled to a fourth terminal of the comparator with the first terminal, to the first current source with the second terminal and to the second terminal of the fourth transistor with the control terminal, wherein the fourth transistor is coupled to the second input of the comparator with the first terminal and to the third input of the comparator with the control terminal, and wherein the first current source is further connected to a reference potential.

19. The driver circuit according to claim 18, wherein the comparator further comprises a second current source coupled to the reference potential and the second terminal of the first transistor, and a third current source coupled to the reference potential and the second terminal of the fourth transistor.

20. The driver circuit according to claim 18, wherein the comparator further comprises a fourth current source and a first resistor, wherein the fourth current source is coupled to the reference potential and to the control terminal of the third transistor via the first resistor.

21. A driver circuit for providing an output signal for switching an electrical load on and off, comprising:

a field-effect transistor comprising a gate terminal and an output for providing the output signal to the electrical load;

a buffer circuit connected to the gate terminal of the field-effect transistor and formed to impress a charge change current at the gate terminal of the field-effect transistor based on a drive signal;

a comparator comprising a first input for receiving a gate voltage of the field-effect transistor and a second input for receiving the output signal;

wherein the comparator is formed to determine whether the gate voltage and the output voltage fulfill a predetermined relationship with respect to each other, and to provide the drive signal to the buffer circuit so that, when the predetermined relationship is fulfilled, the charge change current is changed in magnitude as compared to a charge change current when the predetermined relationship is not fulfilled;

wherein the comparator comprises a third input for receiving an activation signal to allow the comparator to be switched on and off; and

wherein the comparator comprises;

a first transistor comprising a first terminal, a second terminal and a control terminal;

a second transistor comprising a first terminal, a second terminal and a control terminal;

a third transistor comprising a first terminal, a second terminal and a control terminal;

a fourth transistor comprising a first terminal, a second terminal and a control terminal; and

a first current source,

wherein the first transistor is coupled to the first input of the comparator with the first terminal, to the control terminal of the second terminal with the second terminal and to the third input of the comparator with the control terminal,

wherein the second transistor is coupled to a supply voltage with the first terminal and to the first current source with the second terminal,

wherein the third transistor is coupled to a fourth terminal of the comparator with the first terminal, to the first current source with the second terminal and to the second terminal of the fourth transistor with the control terminal,

wherein the fourth transistor is coupled to the second input of the comparator with the first terminal and to the third input of the comparator with the control terminal, and

wherein the first current source is further connected to a reference potential.

22. A driver circuit for providing an output signal for switching an electrical load on and off, comprising:

a field-effect transistor comprising a gate terminal and an output for providing the output signal to the electrical load;

a buffer circuit connected to the gate terminal of the field-effect transistor and formed to impress a charge change current at the gate terminal of the field-effect transistor based on a drive signal; and

a comparator comprising a first input for receiving a gate voltage of the field-effect trnasistor and a second input for receiving the output signal,

wherein the comparator is formed to determine whether the gate voltage and the output voltage fulfill a predetermined relationship with respect to each other, and to provide the drive signal to the buffer circuit so that, when the predetermined relationship is fulfilled, the charge change current is changed in magnitude as compared to a charge change current when the predetermined relationship is not fulfilled,

wherein the driver circuit comprises an input for receiving a control signal to effect switching on or switching off of the electrical load,

wherein the comparator is formed to provide the drive signal to the buffer circuit when a control signal is applied that effects switching on of the electrical load, and when the predetermined relationship is fulfilled, so that the charge change current at the field-effect transistor increases; and

to provide the drive signal to the buffer circuit when the control signal is applied which effects the switching off of the electrical load, and when the predetermined relationship is fulfilled , so that the charge change current at the field-effect transistor is reduced,

wherein the comparator comprises a third input for receiving an activation signal to allow the comparator to be switched on and off, and

wherein the comparator comprises;

a first transistor comprising a first terminal, a second terminal and a control terminal;

a second transistor comprising a first terminal, a second terminal and a control terminal;

a third transistor comprising a first terminal, a second terminal and a control terminal;

a fourth transistor comprising a first terminal, a second terminal and a control terminal; and

a first current source,

wherein the first transistor is coupled to the first input of the comparator with the first terminal, to the control terminal of the second terminal with the second terminal and to the third input of the comparator with the control terminal,

wherein the second transistor is coupled to a supply voltage with the first terminal and to the first current source with the second terminal,

wherein the third transistor is coupled to a fourth terminal of the comparator with the first terminal, to the first current source with the second terminal and to the second terminal of the fourth transistor with the control terminal,

wherein the fourth transistor is coupled to the second input of the comparator with the first terminal and to the third input of the comparator with the control terminal, and

wherein the first current source is further connected to a reference potential.