| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an amplifier that has a characteristic of gain on the output of an output signal so improved that the characteristic of gain becomes closer to a constant characteristic.SOLUTION: An amplifier includes: a first transformer for receiving an input signal at a primary side and outputting a differential signal based on the input signal from a secondary side; a first differential amplification stage connected to the secondary side of the first transformer; a second transformer connected to an output side of the first differential amplification stage; a second differential amplification stage connected to an output side of the second transformer; a third transformer for converting a differential signal output from the second differential amplification stage to a single-ended output signal; and a first bias circuit for supplying a first bias voltage to a secondary coil of the first transformer. The first bias circuit controls the first bias voltage to a first voltage or higher in an operating range where a power of the output signal is a first power or higher on the basis of the input signal such that a characteristic of gain on the power of the output signal becomes closer to a constant characteristic of gain on the power of the output signal.</p> |
