ELECTRONIC DEVICE AND METHOD FOR KICKBACK NOISE REDUCTION OF SWITCHED CAPACITIVE LOADS AND METHOD OF OPERATING THE ELECTRONIC DEVICE

• US 20120092055A1
• Filed: 10/06/2011
• Published: 04/19/2012
• Est. Priority Date: 10/15/2010
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Peschke, Carlo, Muellner, Ernst
• Granted Patent: US 8,922,267 B2
• Time in Patent Office: Days
• US Class Current: 327/306
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H03F 2203/45136 One differential amplifier in IC-block form being shown
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H03M 1/0845 of power supply variations, e.g. ripple

Abstract

An electronic device which includes a first stage having an input capacitance, a switch, a buffer and a second stage having an input sensitive to charge injection and/or voltage glitches. An input of the buffer and the input of the second stage are coupled together at a first node which is configured to be coupled to a voltage source for supplying a reference voltage to the input of the first stage having the input capacitance. In a first configuration of the switch, the switch is arranged to either connect the input of the first stage to the first node and to disconnect the input of the first stage from an output of the buffer. In a second configuration of the switch, to connect the input of the first stage to the output of the buffer and to disconnect the input of the first stage from the first node.

Claims

1. An electronic device comprising:

a first stage (ST1) having an input capacitance (C1), a switch (SW1), a buffer (BUF) and a second stage (ST2) having an input sensitive to charge injection and/or voltage glitches, an input of the buffer and the input of the second stage being coupled together at a first node (N1) which is configured to be coupled to a voltage source for supplying a reference voltage (VREF) to the input of the first stage having the input capacitance, wherein, in a first configuration of the switch, the switch (SW1) is arranged to connect the input (ST1IN) of the first stage to the first node (N1) and to disconnect the input (ST1IN) of the first stage from an output (BUFOUT) of the buffer or, in a second configuration of the switch, to connect the input (ST1IN) of the first stage to the output (BUFOUT) of the buffer and to disconnect the input (ST1IN) of the first stage from the first node (N1).

2. The electronic device according to claim 1, being further configured such that the default configuration of the switch is the second configuration.

3. The electronic device according to claim 1, being further configured to activate the buffer before the switch switches from the second to the first configuration.

4. The electronic device according to claim 1, being further configured to activate the first stage before the switch switches from the second to the first configuration.

5. The electronic device according to claim 4, being further configured to switch the switch from the second to the first configuration only after the output signal of the buffer has settled.

6. The electronic device according to claim 5, being further configured to switch the switch from the first into the second configuration before changing at least one of the voltage or the charge of the input capacitance at the input of the first stage.

7. The electronic device according to claim 6, being further configured to switch the switch into the second configuration before deactivating the first stage.

8. The electronic device according to claim 7, wherein the buffer is deactivated after switching the switch from the second configuration to the first configuration.

9. The electronic device according to claim 7, wherein the buffer is not deactivated after switching the switch from the second to the first configuration.

10. The electronic device according to claim 8, wherein the electronic device is further configured to keep the buffer deactivated when the switch is switched from the first into the second configuration.

11. The electronic device according to claim 10, wherein the first stage comprises a differential amplifier, a comparator, a capacitor or a transistor.

12. The electronic device according to claim 1, wherein the buffer comprises a MOSFET input transistor and an area of an the input transistor is determined as a function of the maximum allowable charge injection into the first node when the switch is switched from the second configuration to the first configuration.

13. A method of operating an electronic device comprising a first stage, a switch, a buffer and a second stage having an input sensitive to charge injection comprising:

activating the buffer;

activating the first stage; and

switching the switch from a second configuration to couple an input of the first stage to an output of the buffer and to disconnect the input of the first stage from a reference voltage to a first configuration to couple an input of the first stage to the reference voltage and disconnect the output of the first stage from the output of the buffer.

14. The method of claim 13, wherein the buffer is activated before the switch switches from the second to the first configuration.

15. The method of claim 13, wherein the first stage is activated before the switch switches from the second to the first configuration.

16. The method of claim 14, wherein the first stage is activated before the switch switches from the second to the first configuration.

17. The method of claim 13, further comprising waiting for an output signal of the buffer to settle before switching the switch from the second to the first configuration.

18. The method of claim 13, further comprising switching the switch from the first to the second configuration before changing at least one of the voltage or charge of the input capacitance at the input of the first stage.

19. The method of claim 18, further comprising switching the switch from the second to the first configuration and then deactivating the buffer.

20. The method of claim 18, wherein the buffer stays activated when the switch is switched from the first to the second configuration.