| 摘要 |
A linear-in-db variable gain amplifier is provided, which approximates gain control characteristics to approximate Linear-in-dB characteristics. A gain G is determined so as to have approximate Linear-in-dB characteristics passing through the maximum value, minimum value, and intermediate value of the gain by a capacitance ratio between capacitance of a higher order capacitor string composed of n capacitors or a lower order capacitor string composed of m capacitors selectively connected in parallel to an input fixed capacitor, and capacitance of a lower order capacitor string, a first correction capacitor string composed of n capacitors, or a second correction capacitor string composed of m capacitors selectively connected in parallel to a feedback loop fixed capacitor, in accordance with a gain control signal (Code) of lower order m bits and higher order n bits.
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