An active rc filter for pcm systems

摘要

AbstractAn active RC low‐pass filter using two high‐gain amplifiers with bridge feedback is described which serves as terminating unit of a PCM system channel. Some conditions derived from telecommunication applications and effecting the choice of the filter structure are discussed in detail, and the principles guaranteeing imaginary zeros under the condition of absolute stability of the filter sections are explained. The measurement results confirm that, using the method described, the fairly severe requirements, particularly the high pass‐band constancy demanded for units of telecommunication equipments, can be met at an economical