| 摘要 |
At least two current mirrors, both responsive to the same input current, the output transistor of the first serving as a current sink for the output current supplied by the second. At least the first mirror is a two-ratio mirror, its output current demand increasing at a rate within the output current supply capacity of the second in a first input current range and increasing at a rate faster than the rate of increase of the output current of the second mirror in a second input current range. A signal detector coupled to the output circuits of both mirrors indicates when the input signal current reaches a given level by detecting when current demanded by said sink exceeds the output current of the second mirror.
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