| 摘要 |
A current amplifier is disclosed, the current gain of which varies directly with changes in input current. A first transistor, arranged as a slave mirroring transistor provides output signal current responsive to a multi-mode transistor master mirroring circuit. The master mirroring circuit includes two master mirroring transistors connected in parallel for receiving input signal current and generating potential for controlling the slave transistor. The first master mirroring transistor includes a serially connected resistor in its principal conduction path, which transistor being arranged to have higher conductance than the second master mirroring transistor, conditions it to receive substantially all of the input signal current for low values of signal and thereby establishing the circuit gain in accordance with the ratio of conductances of the first master and slave mirroring transistors. For higher input signal levels the potential developed across the serially connected resistor causes the input current to be diverted to the second master mirroring transistor thereby establishing the circuit gain in accordance with the conductance ratio of the slave and second master mirroring transistors.
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