一、概述 在通信设备中,压缩—扩张器作为抑制电路串杂音、延长通信距离的有效手段越来越受到人们的重视,不但更多地用于长途通信,而且也开始在市话用户载波通信中使用。可是目前国内各种载波设备使用的压扩器都是由晶体管等分立元件和铁氧体变压器等构成的。例如图1所示的压缩器(a)和扩张器(b)的方框图中,可以看到分别有四个变压器,而且为了得到足够宽的频率特性,变压器铁芯都用得较大、圈数较多、线径较细,这样就造成生产工艺较复杂,技术指标较差,成本也较高。在使用中,由于线圈霉断而造成的故障率也较高。这就限制了压缩—扩张器的广泛使用。如何简化电路和工艺,尽可能不用铁芯变压器,我们作了一些探索。“贝尔技术杂志”1978年4月号发表的“SLC—1环路载波系统”一文中提到把压缩器(或扩张器)集成在一个硅片上,并介绍了它的方框图。我们受此启发,使用集成运算放大器和集成差分放大器等构成无变压器的压缩器与只有一个变压器的扩 I. Overview In communications equipment, compression-dilator as an effective way to suppress the circuit noise and extend the communication distance more and more attention, not only for more long-distance communications, but also began in local carrier communication use. However, at present, all kinds of compression devices used in China’s carrier devices are composed of discrete components such as transistors and ferrite transformers. For example, in the block diagram of compressor (a) and dilator (b) shown in Figure 1, four transformers can be seen separately, and in order to obtain a sufficiently wide frequency characteristic, the transformer cores are used more and the number of turns More, smaller diameter, thus resulting in the production process is more complex, poor technical indicators, the cost is higher. In use, due to the coil mold breakage caused by the higher failure rate. This limits the widespread use of compression-dilators. How to simplify the circuit and technology, as far as possible without iron core transformer, we made some exploration. The “SLC-1 Loop Carrier System,” published by the April 1978 issue of BellTechnology, mentions the integration of a compressor (or expander) on a silicon wafer and presents its block diagram. We are inspired by the use of integrated operational amplifiers and integrated differential amplifier, etc. constitute a transformerless transformer and only one transformer expansion