GB1085178A - Tunnel diode multistable circuit - Google Patents

Abstract

1,085,178. Tristable tunnel diode circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 19, 1965 [Dec. 24, 1964], No. 49206/65. Heading H3T. A switching circuit for use as an amplifier of the first half of a bipolar pulse which is insensitive to the second half, has a current-voltage characteristic with three stable regions separated by two negative resistance regions, and is composed of three parallel current paths, two of which contain tunnel diodes oppositely poled with respect to one another and the third of which consists of a resistor. The two diodes are forwardly biased (Fig. 3, not shown). In a practical form (Fig. 5) the bias sources for the tunnel diodes are in the form of a voltage divider R1, R2 across a voltage source V s . The circuit is initially in its central stable state (A - , Fig. 4, not shown), and a positive current pulse at 11 will switch it to its positive highvoltage state (B), while a negative current pulse will switch it to its negative high-voltage state (C). Switching direct from (B) to (C) or vice versa needs a pulse of greater amplitude than the initial pulse and hence the circuit is insensitive to the second half of a normal bipolar pulse from a thin film magnetic store. Asymmetries in the diode characteristics can be corrected by changing the ratio of R1 and R2, which can be constructed as a potentiometer. The source V s can be a strobe pulse generator with a sharp initial peak to reset the circuit to point A on the characteristic at the end of the peak. The sum of R and the parallel connection of R1 + R2 (in ohms) should be between 4/3 and 4/5 times the ratio of the voltage (in millivolts) provided by the source and the tunnel-diode peak current (in milliamps),