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UBC Theses and Dissertations

The static and dynamic characteristics of series-connected tunnel diodes and their applications in digital circuits Salama, Clement Andre Tewfik


A multistable composite volt-ampere characteristic can be realized using a number of tunnel diodes. A maximum of 2ⁿ stable states can be obtained using n suitably chosen tunnel diodes connected in series. The main purpose of this study is to investigate the static and dynamic characteristics of such a circuit. Preliminary work deals with the switching behaviour of a single tunnel diode and the dependence of the switching time on the figure of merit and the current overdrive. This work serves as a background to the study of the multistate circuit. The study of the static characteristics of the composite device determines the conditions necessary for the generation of the required number of stable states. Additional conditions necessary to ensure proper operation are derived from the study of dynamic characteristics of a two tunnel diode multistate circuit. The dynamic conditions derived involve the tunnel diode capacitances and their ratio. The temperature dependence of the circuit is also investigated. Experimental results are presented showing an operating speed of 12.5 ns for a four state circuit using available tunnel diodes. The versatility of the composite characteristic obtained, and the inherent high speed of the tunnel diodes combine to make the multistate device useful in high-speed digital applications such as: binary addition, analog-to-digital conversion .and counting. These applications are discussed briefly.

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