Ideal Circulator Employing Active Elements therein and its Applications

摘要

1,185,198. Transistor amplifying circuits. HITACHI Ltd. 6 April, 1967 [15 April, 1966], No. 15929/67. Heading H3T. An arrangement which forms an ideal circulator comprises three amplifying stages, i.e. transistors Tr1, Tr2, Tr3 respectively, connected in a closed loop and having as an impedance common to the input and output circuits of all the amplifiers a constant current source, i.e. transistor Tr4. Terminals a, b, c connected to the collector electrodes of transistors Tr1, Tr2, Tr3 respectively constitute the three terminals of the circulator; the Specification gives mathematical expressions for determining the values of the admittances g11 ... g53 which are necessary for the proper functioning of the arrangement. By earthing one of the terminals a, b, c a gyrator is produced (Fig. 4, not shown), while connecting a capacitor between two of the terminals results in apparent inductance between one of these terminals and the third (Figs. 5, 6, not shown). The Specification also describes an arrangement operating as a low-pass filter (Fig. 7, not shown) and a combination of two circulators connected so as to function as a band-pass or high pass filter (Fig. 8, not shown).