| 摘要 |
PURPOSE:To attain amplification of high band with a stable gain by performing high frequency amplification with a current mirror circuit where the emitter size of each element is matched to a desired gain after a voltage signal to be amplified is converted into a current signal. CONSTITUTION:A voltage of a high frequency voltage signal source 100 is converted into a current signal by a resistor 11, fed to a transistor (Tr)20 of diode connection as the input stage of a current amplifier circuit 2 and the same forward bias voltage is given between the base and emitter of Trs 211-21n connected in parallel. The circuit 2 is of current mirror circuit constitution, currents IC21-IC2n the same as the input current Ii flow to the Trs 211-21n, a current being n-times of the current Ii flows to the emitter of the Tr31, converted into a voltage by a resistor 32 and extracted from a terminal 300 as a voltage output. The current amplification factor of the circuit 2 depends on the parallel number (n), which is stable independently of the operating current and temperature. The current amplification factor of the circuit 2 is nS21/S20 and given as (n) with S20=S21, where S20, S21 are emitter areas of Trs 20, 21 respectively.
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