Single or multi-stage switching field for telephone exchanges

Abstract

A multi-stage switching-field formed with switching matrices containing thyristors for stored program controlled switching devices, established by reversal at the last stage, without the use of transformers or other reactive elements therein (e.g. capacitance), in the last stage a holding circuit remains invariable upon switching on, furthermore allocating and switching circuits are ordered to the coupling paths instead of the stages. Circuit arrangements of the switching-field provide the possibility for attenuation control too, and do not require voltages of opposite polarity, while at the same time provide an interface requiring uniform, short operations towards the stored program control device. The switching matrices are switched on at minimal power-level, thus the switching of each further coupling path or connection does not increase the noise level of the already existing connections. The switching-field provides effective protection against unwarranted disconnections caused by noise arriving from the lines, and ensures through impedance matching to attain the optimal ratios of the insertion loss, dynamic range of the connections, and cross-talk attenuation between the different connections. The circuits developed for the switching-field according to the invention are suitable also for production with hydrid or monolithic technology.