| 摘要 |
A variable gain amplifier can improve distortion characteristic (IIP3) in the gain attenuation without deteriorating the characteristic concerning the gain PG and the noise factor NF at the maximum gain. In the variable gain amplifier, a plurality of dual gate type FET are connected in parallel. Each of the dual gate type FET consists of first FET (6, 8) having a gate to which an input signal is applied and second FET (7, 9) cascade-connected to the first FET (6, 8). The amplifier is configured in such a manner that gate control voltage (Vcon1, Vcon2) can be applied from voltage control means to the second FET (7, 9) of each of the dual gate type FET.
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