Patent GB-957043-A (GB)
Title: Electronic semi-conductor device comprising a bistable electric circuit
IPC: H03K17/18
Filed: 1960-05-20
Abstract: 957,043. Semi-conductor devices. SOC. SUISSE POUR L'INDUSTRIE HORLOGERE S.A. May 20, 1960 [May 27, 1959], No. 17921/60. Heading H1K. [Also in Divisions G4 and H3] A bi-stable semi-conductor device comprises two field effect transistors on a support of semi-conductor material and separated therefrom by a reverse biased PN junction, each transistor being connected in series with a resistance and the point of connection between each transistor and its resistance being connected to the gate of the other transistor and, via a capacitor, to a source of alternating voltage switching pulses. Figs. 1 and 2 show an assembly comprising two such bi-stable circuits. A P-type silicon support 1 with ohmic contact 2 carries six N-types regions 3o-3#, each with three ohmic electrodes 5a-5f, 6a-6f and 7a-7# and a P-type zone 4a-4#with electrodes Sa-8#. Connections between the electrodes are established by nickel conductors over silicon oxide insulating layers 18. The circuit is as shown in Fig. 12 and comprises six elements A-F, each consisting of a field effect transistor in series with a resistance; in each case the field effects transistor is provided by ohmic electrodes 4 and 6 with gate electrode 8 and the resistance by the semi-conductor material between ohmic electrodes 6 and 5. Elements A and B constitute one cross-coupled bi-stable pair which are connected via decoupling element E to a second cross-coupled pair C and D; switching pulses are applied via capacitors C 1  and C 2  to gate electrodes 8a and 8b. Electrodes 5 are connected to a positive voltage supply. Assuming, initially, transistors A and D to be non-conducting and transistors B, E and C to be ON, a positive pulse to the input of A and B produces no effect because the low resistance between 6b and 7b effectively prevents the application of the positive pulse to 8a. A negative pulse however drives 8b negative, switching B OFF which drives 6b and 8a positive so switching A ON; the effect is cumulative. The resulting negative pulse from electrode 6a is applied to 8e and thus switches transistor E OFF which results in the application of a positive pulse to the input of elements C and D. As in the case of A and B, this positive pulse produces no effect on C and D. The next negative pulse to A and B would restore these elements to the original conducting state and the resultant positive pulse from 6a would switch E ON to provide a negative pulse to the input of C and D so that these elements are switched whereby D goes ON and C goes OFF. The output from C and D is applied to a further decoupling element F for connection to further bi-stable pairs. In a modification the resistance portion between electrodes 5 and 6 is also provided with an intermediate PN junction (like a field effect transistor) which may be floating or connected to electrode 5 so that the resistance between 5 and 6 is increased; alternatively the additional junction contact may be connected to the other bi-stable component so that, e.g. the resistance between the electrodes 5c and 6c is controlled by the potential of 6d. In another modification, the resistance portion between electrodes 5 and 6 is provided by a semi-conductor layer which is separate from that containing the electrode 6 of the field effect transistor portion; the separated portion for example, may consist of an additional layer of opposite type conductivity on the other one of the pair of bi-stable elements, as shown in Fig. 16, isolation being achieved by means of reverse biasing of the PN junction. Instead of being separate, the portions 3a-3# may be provided by different parts of the same layer.