| 摘要 |
PROBLEM TO BE SOLVED: To provide a broadband amplifier for a mobile telephone adaptable to various standards. SOLUTION: The amplifier according to this invention includes an input amplifier stage, an output amplifier stage cascaded to the input amplifier stage and a load stage connected to the output stage. In particular, the load stage is provided with plural circuits each of which includes a capacitive component and inductive component each having a Q larger than 10 and a different resonance frequency. All of gain curves respectively associated with all circuits have the same maximum gain value, and gain curves associated with two circuits with an adjacent resonance frequency overlaps within 3 dB below a threshold lower than the maximum gain value. This produces an amplifier which is operable at all frequencies from the lowest to the highest resonance frequency while the ratio of the output noise to the input noise is kept very low.
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