envelope detection circuit

例句：

1. 1.The envelope detection circuit is used to detect the presence of a letter inside an envelope.
   信封检测电路用于检测信封内是否存在信件。
2. 2.The envelope detection circuit is essential for ensuring the security of sensitive documents.
   信封检测电路对于确保敏感文件的安全至关重要。
3. 3. The envelope detection circuit can be integrated into various electronic devices to improve their security features.
   信封检测电路可以集成到各种电子设备中，以提高其安全特性。