GB397551A - Improvements in electrical impedance networks and amplifiers - Google Patents

Abstract

397,551. Impedance networks. TELEFONAKTIEBOLAGET L. M. ERICSSON, 33, Kungsgatan, Stockholm. Feb. 26, 1932, No. 5830. Convention date, March 12, 1931. [Classes 40 (iii) and 40 (v).] In an impedance network or amplifying system for equalizing the attenuation or phasedisplacement of currents of different frequencies, the coils of a transformer shunted by a condenser are interposed between one or each leg of the line and an attenuating or retarding line or an amplifier, the characteristic impedance of the whole device being independent of frequency. The system has input terminals 1, 2 and output terminals 3, 4, and the terminals a, c of a quadripole A are connected in the middle of a tapped transformer whose coils L1, L2 are wound on a common core and shunted by a condenser C. The quadripole A may be an amplifier, a resistance network provided with tappings, Fig. 2 (not shown), a retardation line comprising shunt condensers and series inductances, Fig. 3 (not shown), or a combination of the two. The Specification gives the conditions which must be fulfilled in order that the overall characteristic impedance may be independent of frequency. The lower frequencies are attenuated or retarded by the quadripole but the higher frequencies pass mainly through the condenser.