An analysis of tunnel-diode low-level detection is presented for the purpose of explaining some of the unusual detection characteristics that occur under certain bias conditions. For example, in the vicinity of its inflection bias point, a tunnel diode exhibits a discriminator-like rectification behavior with two sensitivity peaks. When biased at one of these peaks, the diode is capable of unusually high sensitivities, at least an order of magnitude better than the sensitivity of any other known diode. It is shown that these high sensitivities are proportional to (1 - /spl Gamma//sup 2/),where /spl Gamma//sup 2/ is the RF power gain of the detector viewed as a reflection-type amplifier. The resultant gain bandwidth (or sensitivity bandwidth) limitations of the detector are discussed. Unusually high sensitivities are also possible at the lower microwave frequencies when the tunnel diode is biased at its peak current point. A knowledge of the diode static characteristics, the reflection coefficient, and the video circuit permits an accurate analytical evaluation of the sensitivity performance of any tunnel diode, and calculations are carried out for an example diode and compared against measured data. The paper also contains a specific comparison of the relative sensitivity performance of the example tunnel diode versus a hot carrier diode.

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Tunnel-Diode Low-Level Detection

Recently, several mechanisms have been proposed as a basis for designing molecular electronic logic switching elements. Many two terminal molecular devices functioning as diodes have been synthesized with responses similar to silicon devices such as rectifying and resonant tunneling diodes. In this paper, the feasibility of integrating these molecular diodes into current circuit architectures is explored. A series of logic gates and a memory element are simulated based on the voltage-controlled current flow method using the Tour-Reed molecular diode exhibiting negative differential resistance (NDR). HSPICE simulation results are used to illustrate the performance of these devices and to quantify additional component and interconnect requirements. Finally, future system design approaches using molecular components are discussed.

Molectronics: a circuit design perspective

Ultrafast optical time-division-multiplexed (TDM) networks will soon be capable of providing data bandwidth at rates exceeding 100Gb/s. Electronic subsystems that will perform routing and computation operations on this data currently reach speeds of 10Gb/s. An electro-optical TDM network is currently being developed at MIT's Lincoln Lab that will optically demultiplex the 100Gb/s data from the network and distribute it to the various slower electronic subsystem. In achieving this goal, one technical challenge that arises is that of buffering and extending the high-speed demultiplexed pulses to levels suitable for the electronic logic. A solution to this problem is proposed, analyzed, constructed and tested. The solution comes in the form of a circuit that uses the high-speed switching capabilities of a resonant tunneling diode (RTD) to interface with the short demultiplexed pulses. A GaAs FET of the type present in the subsequent logic systems is used as a dynamic load for the RTD. The presence of a DC bias voltage allows for a robust design that can accommodate substantial device tolerances. This DC bias also provides a simple method for controlling output pulse characteristics. Thesis Supervisor: J. K. Roberge, Professor of Electrical Engineering, MIT

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A resonant tunneling diode based monostable multivibrator

/pdf/an-investigation-of-tunnel-diode-common-base-transistor-280ydjhvhd.pdf

P.N. Robson

Papers

Parametric and Tunnel Diodes