Switch

• US 20100039160A1
• Filed: 08/12/2008
• Published: 02/18/2010
• Est. Priority Date: 08/12/2008
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Ilkov, Nikolay
• Granted Patent: US 7,868,683 B2
• Time in Patent Office: Days
• US Class Current: 327/374
• CPC Class Codes: H03K 17/04123 in field-effect transistor switches
• CPC Class Codes: H03K 17/102 in field-effect transistor switches
• CPC Class Codes: H03K 2217/0054 Gating switches, e.g. pass gates

Abstract

A switch includes a switching transistor, a switching resistor, connected between a control terminal of the switching transistor and a switching control terminal, and an accelerating element. The accelerating element includes a resistance smaller than a resistance of the switching resistor, the accelerating element being adapted to be connected in parallel to the switching resistor upon switching of the switching transistor until a voltage at the control terminal of the switching transistor has reached a predetermined value.

Claims

1. A switch, comprising:

a switching transistor;

a switching resistor connected between a control terminal of the switching transistor and a switching control terminal; and

an accelerating element comprising a resistance smaller than a resistance of the switching resistor, the accelerating element being adapted to be connected in parallel to the switching resistor upon switching of the switching transistor until a voltage at the control terminal of the switching transistor has reached a predetermined value.

2. The switch as claimed in claim 1, wherein the switching transistor is adapted to be switched by a switching signal at the switching control terminal, and an accelerating control signal is provided to connect the accelerating element in parallel to the switching resistor for a predetermined period of time following a switching control signal transition between two states of the switching control signal.

3. The switch as claimed in claim 2, wherein the predetermined period of time depends on an RC time constant of a circuit comprising the switching transistor, the switching resistor and the accelerating element.

4. The switch as claimed in claim 2, wherein the switching control signal comprises a first signal state effecting a conductive state of the switching transistor and a second signal state effecting a blocking state of the switching transistor;

the accelerating control signal comprises a first signal state connecting the accelerating element in parallel to the switching resistor during the predetermined period of time following a transition of the switching control signal between the first and second states.

5. The switch as claimed in claim 4, wherein the accelerating control signal is adapted to change to a second signal state disconnecting the accelerating element from the switching resistor responsive to an expiration of the predetermined period of time.

6. The switch as claimed in claim 1, further comprising an accelerating switch controlled by an accelerating control signal and being adapted to switch the accelerating element in parallel to the switching resistor.

7. The switch as claimed in claim 6, wherein the accelerating element comprises an accelerating resistor connected between the control terminal of the switching transistor and the switching control terminal.

8. The switch as claimed in claim 1, wherein the accelerating element comprises a diode connected between the control terminal of the switching transistor and the switching control terminal, the diode being adapted to be controlled by an accelerating control signal.

9. The switch as claimed in claim 1, wherein the accelerating element comprises an accelerating transistor comprising a first terminal connected to the control terminal of the switching transistor, a second terminal connected to the switching control terminal and a control terminal, the control terminal being adapted to receive an accelerating control signal.

10. The switch as claimed in claim 9, wherein the accelerating transistor comprises a channel width smaller than a channel width of the switching transistor.

11. The switch as claimed in claim 1, wherein the accelerating element comprises a plurality of accelerating transistors connected in series between the control terminal of the switching transistor and the switching control terminal, the control terminals of the plurality of accelerating transistors being adapted to receive an accelerating control signal.

12. The switch as claimed in claim 11, comprising

a plurality of switching transistors connected in series;

and

a plurality of switching resistors, each of the switching resistors being associated with one of the plurality of switching transistors;

wherein each of the plurality of accelerating elements is associated with one of the switching resistors.

13. The switch as claimed in claim 12, comprising:

an input terminal and an output terminal, wherein the plurality of switching transistors is connected between the input terminal and the output terminal;

a second switching transistor connected between the output terminal and a reference terminal with respect to channel terminals of the second switching transistor;

a second switching resistor connected between a control terminal of the second switching transistor and a second switching control terminal; and

a second accelerating element, comprising a resistance smaller than a resistance of the second switching resistor, the second accelerating element being adapted to be connected in parallel to the second switching resistor upon switching of the second switching transistor until a voltage of the control terminal at the control terminal of the second switching transistor has reached a predetermined value.

14. The switch as claimed in claim 13, comprising:

a plurality of second switching transistors;

a plurality of second switching resistors, each being associated with one of the plurality of second switching transistors; and

a plurality of second accelerating elements, each being associated with one of the plurality of second switching resistors.

15. The switch as claimed in claim 13, wherein the second switching transistor is adapted to be switched by a switching signal at the switching control terminal, and a second accelerating control signal is provided to connect the second accelerating element in parallel to the second switching resistor for a second predetermined period of time following a switching control signal transition between two states of the switching control signal.

16. The switch as claimed in claim 15, wherein the second predetermined period of time depends on an RC time constant of a circuit comprising the second switching transistor, the second switching resistor and the second accelerating element.

17. The switch as claimed in claim 15, wherein the switching control signal comprises a first signal state effecting a conductive state of the second switching transistor and a second signal state effecting a blocking state of the second switching transistor;

the second accelerating control signal comprises a first signal state connecting the second accelerating element in parallel to the second switching resistor during the second predetermined period of time following a transition of the switching control signal between the first and second states.

18. The switch as claimed in claim 17, wherein the second accelerating control signal is adapted to change to a second signal state disconnecting the second accelerating element from the second switching resistor responsive to an expiration of the second predetermined period of time.

19. The switch as claimed in claim 1, wherein the switching transistor and the accelerating transistor comprise CMOS FETs or wherein the accelerating transistor comprises a JFET.

20. A switch, comprising:

an input terminal;

an output terminal;

a switching terminal;

a first switching transistor connected between the input terminal and the output terminal;

a first switching resistor connected between a control terminal of the first switching transistor and the switching control terminal;

a first accelerating element comprising a resistance smaller than a resistance of the first switching resistor;

a second switching transistor connected between a reference terminal and the output terminal;

a second switching resistor connected between a control terminal of the second switching transistor and the switching control terminal; and

a second accelerating element comprising a resistance smaller than a resistance of the second switching resistor,

the first and second accelerating elements being adapted to be connected in parallel to the first and second switching resistors, respectively, upon switching of the first and second switching transistors until capacitances at the control terminal of the first and second switching transistor have reached respective predetermined capacitances.

21. The switch as claimed in claim 20, wherein each of the first switching transistor, the second switching transistor, the first accelerating element and the second accelerating element comprises a plurality of FETs connected in series;

wherein a channel width of the FETs of the first and second accelerating elements is smaller than a channel width of the FETs of the first and second switching transistors, and

wherein the first and second accelerating elements are connected in parallel to the respective switching resistors responsive to a first accelerating control signal and a second accelerating control signal;

wherein the first and second accelerating control signals change to a first state responsive to a transition of a switching control signal at the switching control terminal between a first state and a second state, the first state of the first and second accelerating control signals causing a parallel connection of the accelerating element to the respective switching transistors; and

wherein the first and second accelerating control signals remain in the first state during first and second predetermined periods of time following the transition of the respective switching control signals, the time periods being determined by an RC constant of a circuit comprising the respective switching transistors, the respective switching resistors and the respective accelerating elements.

22. The switch of claim 20, comprising a controller adapted to receive a switching control signal and to provide an accelerating control signal, the controller comprising:

an inverter adapted to invert the switching control signal to provide an inverter output signal;

an RC low-pass filter adapted to low-pass filter the switching control signal to provide a low-pass filter output signal;

a Schmitt-trigger-circuit adapted to convert the low-pass filter output signal to a Schmitt-trigger-circuit output signal; and

a NAND gate adapted to combine the inverter output signal and the Schmitt-trigger-circuit output signal by a logical NAND combination to provide the accelerating control signal.

23. The switch as claimed in claim 22, wherein the controller comprises:

a second inverter adapted to invert the Schmitt trigger circuit output signal to provide a second inverter output signal; and

a second NAND gate adapted to combine the switching control signal and the second inverter output signal by a logical NAND combination to provide a second accelerating control signal.

24. A switch, comprising:

switching means comprising an RC time constant;

means for reducing the RC time constant of the switching means for a predetermined time period during switching.

25. A method for switching a switching transistor comprising a switching resistor connected to a control terminal of the switching transistor, the method comprising:

switching an accelerating element, comprising a resistance smaller than a resistance of the switching resistor, in parallel to the switching resistor upon switching of the switching transistor until a voltage at the control terminal of the switching transistor has reached a predetermined value.