Voltage regulator

• US 20060033555A1
• Filed: 08/02/2004
• Published: 02/16/2006
• Est. Priority Date: 08/02/2004
• Status: Active Grant

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Sridharan, Srinath
• Granted Patent: US 7,205,828 B2
• Time in Patent Office: Days
• US Class Current: 327/540
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit

Abstract

A voltage regulator configured to provide a regulated voltage to a load having a first conductance is provided. The voltage regulator comprises a feedback circuit configured to generate the regulated voltage and a frequency compensation circuit comprising a first MOSFET device having a second conductance. The frequency compensation circuit is configured to operate the first MOSFET device so that the second conductance varies in response to the first conductance of the load.

Claims

1. A voltage regulator configured to provide a regulated voltage to a load having a first conductance, the voltage regulator comprising:

a feedback circuit configured to generate the regulated voltage; and

a frequency compensation circuit comprising a first MOSFET device having a second conductance;

wherein the frequency compensation circuit is configured to operate the first MOSFET device so that the second conductance varies in response to the first conductance of the load.

2. The voltage regulator of claim 1 wherein the feedback circuit comprises a second MOSFET device having a transconductance, wherein the frequency compensation circuit comprises a third MOSFET device having a third conductance, and wherein the frequency compensation circuit is configured to operate the third MOSFET device so that the third conductance varies in response to the transconductance of the second MOSFET device.

3. The voltage regulator of claim 2 wherein the frequency compensation circuit comprises a first bias circuit and a second bias circuit, wherein the first bias circuit is configured to provide a first voltage to the third MOSFET device to cause the third conductance to vary in response to the transconductance of the second MOSFET device, and wherein the second bias circuit is configured to provide a second voltage to the first MOSFET device to cause the second conductance to vary in response to the first conductance.

4. The voltage regulator of claim 3 wherein the first bias circuit comprises a fourth MOSFET device having a gate connection and a drain connection and a current source connected to the gate connection, the drain connection, and a ground node, and wherein the current source is configured to draw a current from the fourth MOSFET device to generate the first voltage.

5. The voltage regulator of claim 3 wherein the second bias circuit comprises a fourth MOSFET device, a fifth MOSFET device, a sixth MOSFET device, a first current source, a second current source, and a resistive element having a first end and a second end, wherein the first current source is configured to draw a first current from the fourth MOSFET device through the resistor to generate a third voltage which is provided to the fifth MOSFET device, and wherein the second current source is configured to draw a second current from the fifth MOSFET device and the sixth MOSFET device to generate the second voltage.

6. The voltage regulator of claim 5 wherein the first current source is proportional to a master generated current source.

7. The voltage regulator of claim 5 wherein the second current source is proportional to a third current drawn by the load.

8. The voltage regulator of claim 2 wherein the feedback circuit further comprises a bias circuit configured to provide a bias voltage to the second MOSFET device to control a feedback current though the second MOSFET device.

9. The voltage regulator of claim 2 wherein the feedback circuit further comprises a fourth MOSFET device, and wherein the fourth MOSFET device is configured to provide a load current to the load and the feedback current to the second MOSFET device.

10. The voltage regulator of claim 9 wherein the frequency compensation circuit further comprises a capacitive element having a first end connected to the fourth MOSFET device and a second end connected to the first MOSFET device and the third MOSFET device.

11. A method performed by a voltage regulator comprising:

providing a regulated voltage to a load having a first conductance; and

compensating for first variations in the first conductance of the load.

12. The method of claim 11 further comprising:

compensating for the first variations in the first conductance of the load by causing a second conductance of a first MOSFET device to track the first conductance.

13. The method of claim 12 further comprising:

providing a first biasing voltage associated with a current drawn by the load to the first MOSFET device.

14. The method of claim 12 further comprising:

compensating for second variations in a transconductance of a portion of the voltage regulator.

15. The method of claim 14 further comprising:

compensating for the second variations in the transconductance of the portion of the voltage regulator by causing a third conductance of a second MOSFET device to track the transconductance.

16. The method of claim 15 further comprising:

providing a second biasing voltage associated with a current drawn by the portion of the voltage regulator to the second MOSFET device.

17. A system comprising:

a functional unit having a first conductance; and

a voltage regulator comprising;

a first circuit configured to provide a regulated voltage to the functional unit; and

a second circuit comprising a first MOSFET device having a second conductance;

wherein the second circuit is configured to operate the first MOSFET device so that the second conductance tracks the first conductance of the functional unit.

18. The system of claim 17 further comprising:

a transceiver that comprises the functional unit.

19. The system of claim 18 wherein the transceiver is configured for use in a Global System for Mobile Communications (GSM) network.

20. The system of claim 17 wherein the second circuit is configured to operate the first MOSFET device in a linear region of the first MOSFET device.

21. The system of claim 17 wherein the second circuit is configured to provide a voltage to the first MOSFET device to cause the second conductance to track the first conductance of the functional unit.

22. The system of claim 21 wherein the second circuit comprises a first current source configured to generate a first current that is proportional to a second current provided to the functional unit, and wherein the second circuit is configured to generate the voltage using the first current.

23. The system of claim 22 wherein the second circuit comprises a second current source configured to generate a third current that is proportional to a third current generated by a master calibrated current source, and wherein the second circuit is configured to generate the voltage responsive to the second current.

24. The system of claim 17 wherein the first conductance varies over time.

25. The system of claim 17 wherein the first circuit comprises a second MOSFET device having a transconductance, wherein the second circuit comprises a third MOSFET device having a third conductance, and wherein the second circuit is configured to operate the third MOSFET device so that the third conductance varies in response to the transconductance of the second MOSFET device.

26. A voltage regulator for providing a regulated voltage to a load having a first conductance comprising:

a circuit configured to provide the regulated voltage to the load;

first means for generating a second conductance;

second means for operating the first means so that the second conductance tracks the first conductance of the load.

27. The voltage regulator of claim 26 wherein the second means includes third means for providing a voltage to the first means to cause the second conductance to track the first conductance of the load.

28. The voltage regulator of claim 26 wherein the first conductance of the load varies over time.

29. The voltage regulator of claim 26 wherein the circuit comprises a first MOSFET device having a transconductance, and further comprising:

third means for generating a third conductance; and

fourth means for operating the third means so that the third conductance tracks the transconductance of the first MOSFET device.

30. The voltage regulator of claim 29 wherein the fourth means includes fifth means for providing a voltage to the third means to cause the third conductance to track the transconductance of the first MOSFET device.

31. The voltage regulator of claim 29 wherein the circuit is configured to provide a bias voltage to the first MOSFET device to control a feedback current though the first MOSFET device.

32. The voltage regulator of claim 29 wherein the circuit further comprises a second MOSFET device, and wherein the second MOSFET device is configured to provide a load current to the load and the feedback current to the first MOSFET device.

33. The voltage regulator of claim 29 wherein the first means comprises a second MOSFET device and wherein the third means comprises a third MOSFET device.

34. The voltage regulator of claim 33 wherein the second means is for operating the first means in a linear region of the second MOSFET device, and wherein the fourth means is for operating the third means in a linear region of the third MOSFET device.