| 摘要 |
An accurate, low-current integrated circuit comparator includes a differential input stage 10 comprising differential pair transistors 22 and 24, differential pair current mirror transistors 26 and 28, and a constant current source transistor 30. The comparator also includes an hysteresis stage 12 coupled to one of the current mirror transistors; the hysteresis stage comprises an hysteresis mirror transistor 34 and a switching transistor 36. The comparator additionally includes a gain stage 14 comprising a gain transistor 38 and a constant current source transistor 40. Finally, the comparator includes an output stage 15 comprising gain transistor 42 in an open-drain configuration. In the disclosed embodiment, the descending trip threshold is set entirely by the ratios of device geometries, and is therefore very accurate and is independent of temperature, lithography and processing variations. While the ascending trip threshold is related to the ratio of tail current of the differential pair to the transistor gain of the devices in that pair, which quantities are dependent on the device parameters, this relationship is only to the one-half power, and therefore is relatively small.
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