COMPARATOR CIRCUITS WITH LOCAL RAMP BUFFERING FOR A COLUMN-PARALLEL SINGLE-SLOPE ADC

摘要

A comparator circuit suitable for use in a column-parallel single-slope analog-to-digital converter comprises a comparator, an input voltage sampling switch, a sampling capacitor arranged to store a voltage which varies with an input voltage when the sampling switch is closed, and a local ramp buffer arranged to buffer a global voltage ramp applied at an input. The comparator circuit is arranged such that its output toggles when the buffered global voltage ramp exceeds the stored voltage. Both DC- and AC-coupled comparator embodiments are disclosed.

主权项

1. A comparator circuit suitable for use in a column-parallel single-slope analog-to-digital converter, said comparator circuit comprising:
an input node; a comparator; an input voltage sampling switch coupled to said input node; a sampling capacitor arranged to store a voltage which varies with an input voltage applied to said input node when said sampling switch is closed; and a local ramp buffer having an associated input and arranged to buffer a global voltage ramp applied directly to said local ramp buffer's input; said comparator circuit arranged such that the output of said comparator toggles when said buffered global voltage ramp exceeds said stored voltage.