Auto-zero technique for opamps with a source-follower output stage based on replica referencing

摘要

An electronic circuit comprises an input stage, a gain stage operatively coupled to the input stage, a primary output stage operatively coupled to the gain stage, a replica output stage operatively coupled to the gain stage in parallel to the primary output stage, and a clock circuit. The clock circuit operates the electronic circuit in multiple phases including a sampling phase to disconnect the primary output stage and the replica output stage from the gain stage to obtain an offset voltage, an active phase to reconnect the primary output stage to apply the offset voltage to reduce an offset at the primary output stage, and an intermediate phase to first reconnect the replica output stage to the gain stage prior to the active phase.