Method and system for correcting non-linear response in amplifiers

1. A method for extending the linear range of operation of an amplifier, comprising:

monitoring a transistor voltage of a transistor of an amplifier, the transistor coupled to a variable current source applying a bias current to the transistor;

monitoring an output voltage of the amplifier;

determining whether the transistor voltage is within a predetermined range of the output voltage;

if the transistor voltage is not within a predetermined range of the output voltage, decreasing the bias current applied to the transistor; and

if the transistor voltage is within a predetermined range of the output voltage and if the bias current has not previously been decreased, increasing the bias current applied to the transistor.

2. The method of claim 1 , wherein the transistor voltage is determined to be within the predetermined range when the transistor voltage is equal to or no more than a predetermined amount less than the output voltage.

3. The method of claim 1 , wherein the transistor voltage is determined to be outside the predetermined range if the transistor is saturated.

4. The method of claim 1 , wherein increasing the bias current applied to the transistor comprises increasing the bias current to a maximum current provided by the variable current source.

5. The method of claim 1 , wherein:

the variable current source is a first variable current source applying a first bias current;

the transistor is a first transistor; and

the method further comprises adjusting a second bias current applied by a second variable current source to a second transistor having at least one terminal coupled to the first transistor in response to any adjustment of the first bias current.

6. The method of claim 1 , wherein the output voltage of the amplifier is proportional to an output current of the transistor, the method further comprising:

detecting a non-linear fluctuation in the output current of the transistor;

generating a compensation current associated with the non-linear fluctuation; and

applying the compensation current to the transistor.

7. The method of claim 6 , wherein:

the transistor comprises a first transistor;

the compensation current is generated by a second transistor coupled to the first transistor; and

the first and second transistors are further coupled to a constant current source.

8. The method of claim 1 , wherein the steps of the method are implemented in an integrated circuit.

9. An amplifier, comprising:

a transistor;

a variable current source coupled to the transistor operable to apply a bias current to the transistor; and

a current control module operable to:

monitor a transistor voltage of the transistor;

monitor an output voltage of the amplifier;

determine whether the transistor voltage is within a predetermined range of the output voltage;

decrease the bias current applied to the transistor if the transistor voltage is not within a predetermined range of the output voltage;

increase the bias current applied to the transistor if the transistor voltage is within a predetermined range of the output voltage and the bias current has not previously been decreased.

10. The amplifier of claim 9 , wherein the transistor voltage is determined to be within the predetermined range when the transistor voltage is equal to or no more than a predetermined amount less than the output voltage.

11. The amplifier of claim 9 , wherein the transistor voltage is determined to be outside the predetermined range if the transistor is saturated.

12. The amplifier of claim 9 , wherein the current control module increases the bias current applied to the transistor to a maximum current provided by the variable current source.

13. The amplifier of claim 9 , wherein:

the variable current source is a first variable current source applying a first bias current;

the transistor is a first transistor;

the amplifier further comprises:

a second transistor having at least one terminal coupled to the first transistor; and

a second variable current source coupled to the second transistor operable to apply a second bias current to the second transistor; and

the current control module is further operable to adjust the second bias current in response to an adjustment of the first bias current.

14. The amplifier of claim 9 , wherein:

the output voltage of the amplifier is proportional to an output current of the transistor; and

the transistor comprises a first transistor;

the amplifier further comprising a second transistor having at least one terminal coupled to the first transistor, the second transistor operable to:

detect a non-linear fluctuation associated with the output current of the first transistor;

generate a compensation current in response to detecting the non-linear fluctuation; and

apply the compensation current to the first transistor.

15. An amplifier, comprising:

a first transistor;

a second transistor having at least one terminal coupled to the first transistor;

a first variable current source coupled to the first transistor and operable to apply a first bias current to the first transistor;

a second variable current source coupled to the second transistor and operable to apply a second bias current to the second transistor; and

a current control module operable to:

monitor a transistor voltage of the first transistor;

monitor an output voltage of the amplifier;

determine whether the transistor voltage is within a predetermined range of the output voltage;

decrease the first bias current if the transistor voltage is not within a predetermined range of the output voltage;

increase the first bias current if the transistor voltage is within a predetermined range of the output voltage and the first bias current has not previously been decreased.

16. The amplifier of claim 15 , wherein the transistor voltage is determined to be within the predetermined range when the transistor voltage is equal to or no more than a predetermined amount less than the output voltage.

17. The amplifier of claim 15 , wherein the transistor voltage is determined to be outside the predetermined range if the first transistor is saturated.

18. The amplifier of claim 15 , wherein the current control module increases the first bias current applied to the first transistor to a maximum current provided by the first variable current source.

19. The amplifier of claim 15 , wherein the current control module is further operable to adjust the second bias current in response to an adjustment of the first bias current.

20. The amplifier of claim 15 , wherein the output voltage of the amplifier is proportional to an output current of the first transistor, and the second transistor operable to:

detect a non-linear fluctuation associated with the output current of the first transistor;

generate a compensation current in response to detecting the non-linear fluctuation; and

apply the compensation current to the first transistor.

21. A system, comprising:

means for monitoring a transistor voltage of a transistor of an amplifier, the transistor coupled to a variable current source applying a bias current to the transistor;

means for monitoring an output voltage of the amplifier;

means for determining whether the transistor voltage is within a predetermined range of the output voltage;

means for decreasing a bias current applied to the transistor if the transistor voltage is not within a predetermined range of the output voltage; and

means for increasing the bias current applied to the transistor if the transistor voltage is within a predetermined range of the output voltage and if the bias current has not previously been decreased.