| 摘要 |
An FET band amplifier for providing a high gain. An FET band amplifier (5) included in an AM receiver comprises amplifiers (11-15) e.g. at five stages and a BPF (16) inserted halfway in their connection. Each of the amplifiers (11-15) acts as a differential amplifier comprising a p-channel FET as an amplification element. The BPF (16) allows the passage of a component of a band wider than the amplification band of the whole of the FET band amplifier and reduces a 1/f noise by removing the low-band component of a signal amplified by the amplifiers (11-13) at three stages and thermal noise by removing the high-band component. Thus, each of the amplifiers (14, 15) connected to the rear stage of the BPF (16) is not saturated by a noise component.
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