Amplitude modulating circuit |
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| 申请号 | JP16839479 | 申请日 | 1979-12-26 | 公开(公告)号 | JPS5691509A | 公开(公告)日 | 1981-07-24 |
| 申请人 | Hitachi Ltd; Hitachi Tokyo Electronics Co Ltd; | 发明人 | ISHIGAMI YASUHIKO; | ||||
| 摘要 | PURPOSE:To enable amplitude modulation with simple constitution by controlling MISFET as a variable resistance provided to the negative feedback path of an operational amplifier. CONSTITUTION:The uninverted input terminal of operational amplifier 1 is grounded and to the inverted input terminal, different sound frequency signals are inputted via resistances R1 and R2. At its output terminal, the sum of the different sound frequency signals appears. Then, negative feedback is provided from the output terminal of operational amplifier 1 to its inverted input terminal. The negative feedback resistance is provided with MISFET. Since MISFET can vary in resistance value with control voltage VG, the gain of the amplifier can be controlled. Using as the control voltage a voltage varying by steps enables this circuit to be used widely as a circuit which obtains a volumelike display output signal. | ||||||
| 权利要求 | |||||||
| 说明书全文 | |||||||
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