| 摘要 |
A circuit for supplying a pair of currents that vary in opposite directions as a function of a control current. The pair of currents are coupled to an amplifying stage in which the gain varies in accordance with the relative magnitude of the currents. The circuit includes a differential current source having two output current terminals and a pair of controlled inputs. Both inputs are coupled to individual current sources. One input includes a resistor-diode current sink and the other input includes a current mirror sink. The control current is coupled to the current mirror thus varying the load on the related differential inputs. The current mirror input is also coupled to the diode current sink in the one differential input so that a delay can be introduced into the response to control current. That is, the control current must exceed a predetermined value before the gain reduction action occurs.
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