Method and apparatus for compensation of second order distortion
AssigneeInfineon Technologies AG
InventorsStephen J. Franck, Thomas Blon
Life of this patent
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Abstract
A method and apparatus for removing second order distortion is disclosed. The method couples a differential load between two source followers of a gain stage. The apparatus includes a differential load having two MOS transistors of unequal channel width/length ratios. The differential load implements a square and summing function in a single circuit eliminating the need to split the signal path.
Claims30
An amplifier stage comprising:
- a first source follower including a first transistor comprising a first source, a first gate and a first drain, said first drain coupled with a first current source and a first differential output, said first gate coupled with a first differential input, said first source coupled with a second current source;
- a second source follower including a second transistor comprising a second source, a second gate and a second drain, said second drain coupled with a third current source and a second differential output, said second gate coupled with a second differential input, said second source coupled with a fourth current source;
- a distortion compensator coupled between said first source follower and said second source follower, said distortion compensator comprising a differential load;
- and
- wherein said distortion compensator is operative to remove second order distortion from a differential analog signal input to said first and second differential inputs.
A method of removing second order distortion from a differential analog input signal, the method comprising:
- (a) receiving said differential analog input signal at first and second source followers;
- (b) processing said differential analog input signal through a differential load;
- (c) removing second order distortion from said differential analog input signal.
An apparatus for removing second order distortion from a differential analog input signal, the apparatus comprising:
- a gain stage operative to receive a differential analog signal from an input source and amplify said signal to differential outputs;
- a differential load coupled with said gain stage and operative to remove second order distortion from said differential analog signal in line;
- said differential load comprising first and second transistors having unequal channel width-to-length ratios.
An amplifier stage comprising:
- a first source follower including a first transistor comprising a first source, a first gate and a first drain, said first drain coupled with a first current source and a first differential output, said first gate coupled with a first differential input, said first source coupled with a second current source;
- a second source follower including a second transistor comprising a second source, a second gate and a second drain, said second drain coupled with a third current source and a second differential output, said second gate coupled with a second differential input, said second source coupled with a fourth current source;
- a distortion compensator means coupled between said first source follower and said second source follower and operative to remove second order distortion from a differential analog signal input to said first and second differential inputs.
Dependencies are inferred from the claim text.