A BISTABLE ELECTRICAL CIRCUIT

• Main Author: SIEGFRIED KURT WIEDMANN
• Format: Patent
• Language: English
• Published: 14.10.1970
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; INFORMATION STORAGE; PHYSICS; PULSE TECHNIQUE; STATIC STORES

1,208,526. Transistor bi-stable circuits. INTERNATIONAL BUSINESS MACHINES CORP. 14 April, 1969 [13 April, 1968], No. 18970/69. Heading H3T. A cross-coupled bi-stable transistor pair T1, T2 deriving its emitter and collector supply potentials from a source 10, is switched in response to a pulse at B1, or B0 by raising the potential of the complete bi-stable (by a pulse from 10) relatively to a switching circuit, such as an emitter-coupled pair of transistors T3, T4. If T2 is OFF, and a " 1 " pulse is applied at B1, then when the pulse from 10 raises the potential V0 the base-emitter junction of T4 becomes forward biased and T4 conducts, the base current therein producing a potential drop across the collector resistor RC2 of T2 which is sufficient to turn off T1, and thus change the state of the bi-stable. Raising the potential of the bi-stable, instead of lowering the potential of the switching circuit transistors T3, T4 as happens in what is said to be the known circuit of Fig. 1 (not shown), enables the collector diodes (D0, D1) to be dispensed with. This facilitates integrated circuit construction, in which the collectors of the T3 transistors in a plurality of identical bi-stable stages are all formed in a common semi-conductor block; and similarly for the T4 collectors.