| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier circuit having excellent NF characteristics even in a high frequency region. SOLUTION: The amplifier circuit is provided with an emitter-grounded first bipolar transistor and a bias circuit of the first bipolar transistor. The bias circuit is provided with a second bipolar transistor constituting a current mirror circuit with the first bipolar transistor, a first resistor connected to respective bases of the first bipolar transistor and the second bipolar transistor, and a third bipolar transistor whose emitter is connected to the respective bases of the first bipolar transistor and the second bipolar transistor through the first resistor and the base is connected to the collector of the second bipolar transistor. The first bipolar transistor amplifies signals inputted to the base of the first bipolar transistor and outputs them from the collector of the first bipolar transistor. COPYRIGHT: (C)2008,JPO&INPIT
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