| 摘要 |
A constant ratio current source comprises a first current branch which includes a first transistor that conducts a current I 1 from a first current input to a first node and a resistor R 1 connected between the first node and a circuit common point, and a second current branch which includes a second transistor that conducts a current I 2 from a second current input to a second node and a resistor R 2 connected between the second node and the circuit common point. The current branches are arranged such that I 2 varies with I 1 . A linear negative resistance circuit connected between the first and second nodes provides an apparent negative resistance that increases the differential output impedance at the first and second current inputs, such that the ratio of I 2 :I 1 is maintained approximately constant for a varying differential voltage applied across the first and second current inputs.
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