Differential amplifier
AssigneeFujitsu Limited
InventorKohei Shibata
Life of this patent
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Abstract
A differential amplifier having an integrated resistance load type differential pair in which a constant current which varies to suppress a small signal gain variation of a resistance load type differential pair caused by variations of circumferential conditions and manufacturing process conditions and a constant current which varies to suppress a limiter amplitude variation of the resistance load type differential pair caused by the variations of the same conditions are mixed at a fixed ratio under a condition which is most frequently used among the circumferential conditions and a condition which is best achieved among the manufacturing process conditions, which is used as a bias current of the differential pair.
Claims14
A differential amplifier comprising:
- an integrated resistance load type differential pair;
- a gain variation suppressing type current source for generating a first predetermined constant current to suppress a small signal gain variation of the integrated resistance load type differential pair, caused by variations of circumferential conditions and manufacturing process conditions;
- a resistance variation suppressing type current source for generating a second predetermined constant current to suppress a limiter amplitude variation of the integrated resistance load type differential pair, caused by variations of the circumferential conditions and the manufacturing process conditions;
- a mixing means connected to the gain variation suppressing type current source and the resistance variation suppressing type current source for mixing the first and second predetermined constant currents mixed at a constant ratio under a condition most frequently used among the circumferential conditions and best achieved among the manufacturing process conditions, and
- a bias current source connected to the integrated resistance load type differential pair to provide a constant current mixed by the mixing means as a bias current for the integrated resistance load type differential pair.
Dependencies are inferred from the claim text.