variable gain device

例句：

1. 1. The variable gain device is used to amplify the signal.
   可变增益装置用于放大信号。
2. 2. The variable gain device was developed to improve the performance of the system.
   可变增益装置被开发出来以提高系统的性能。
3. 3. The variable gain device can be used in various applications, such as audio and video recording.
   可变增益装置可以在各种应用中使用，如音频和视频录制。