The present invention relates to a high-frequency amplifier circuit that outputs differential signals, a semiconductor device, and a magnetic recording and reproducing device.
High-frequency amplifier circuits used in radio communication and the like widely employ a multistage configuration using a plurality of amplifiers so as to attain desired power for a load. Furthermore, differential signals are used for various purposes, such as improving noise immunity and reducing power consumption, and in cases where it is difficult to place a ground electrode. However, in the case where a high-frequency amplifier circuit having a multistage configuration outputs differential signals, for example, when a common-mode component is generated in the circuit, abnormal oscillation may occur in the amplifier via a feedback path, such as a power line or a signal line, which has been a problem. Note that in order to output differential signals at the last stage in a high-frequency amplifier circuit, one differential amplifier including two amplifiers having the same properties or a dual configuration including two amplifiers having the same properties placed in parallel may be used.