| 摘要 |
An offset cancellation circuit for canceling an offset voltage in an amplifier is provided herein. The offset cancellation circuit includes a current source configured to provide an offset current, a switching stage comprising first and second switches, and a cascode stage. The cascode stage comprises a first cascode device configured to receive the offset current from the first switch and inject the offset current into a first differential end of the amplifier, and a second cascode device configured to receive the offset current from the second switch and inject the offset current into a second differential end of the amplifier. Offset voltages are common to many differential circuits as a result of mismatch. The injection of current by the offset cancellation circuit can reduce or eliminate an offset voltage, while the cascode stage can prevent parasitic capacitance associated with the offset cancellation circuit from creating further mismatch.
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