| 摘要 |
A method and apparatus for compensating for offset and drift of offset in an amplifier circuit having metal oxide semiconductor transistors in an input stage thereof and including a node responsive to a bias to change the offset of the amplifier circuit. In one embodiment, an offset digital-to-analog converter provides a first programmable bias corresponding to an offset of the amplifier circuit. A drift digital-to-analog converter provides a second programmable bias corresponding to a drift of the offset of the amplifier circuit. The first programmable bias and the second programmable bias are combined and coupled to the node. In another embodiment, a first programmable offset/drift generator is provided, capable of sourcing a first bias to the amplifier node compensating for a first portion of the offset and a first portion of the drift of the offset of the amplifier circuit. A second programmable offset/drift generator is provided, capable of sourcing a second bias to the amplifier node compensating for a second portion of the offset and a second portion of the drift of the offset of the amplifier circuit, wherein the rate of drift compensation with temperature of the second bias is different from the rate of compensation of the second bias. By suitable programming of the first and second programmable offset/drift generators the compensation of the offset and the offset of the drift of the amplifier circuit may be optimized.
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