| 摘要 |
A current-matching variable gain amplifier is provided. The amplifier comprises a reference current source, at least one cascode amplifier, a matching circuit, a control circuit, and at least one first blocking circuit. The reference current source provides a reference current. Each of the cascode amplifiers amplifies an input signal according to the reference current. The matching circuit equalizes the voltage level at a first node in each cascode amplifier and the voltage level at a second node in the matching circuit. The matching circuit also equalizes the current of a main MOSFET of each cascode amplifier and the current of a first MOSFET of the matching circuit. The control circuit controls the current of the first MOSFET of the matching circuit. Each of the first blocking circuit(s) corresponds with the cascode amplifier, and is coupled between the reference current source and the corresponding cascode amplifier, for blocking RF signals.
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