Analog/digital circuit applications using resonant tunneling diodes

Two kinds of RTD A/D converter are described in this dissertation: self-latching A/D converters and a current-mode A/D converter. These A/D converters take advantage of the folding characteristic of RTD to reduce the circuit complexity. The speed response of the A/D converters is improved by the fast latching action of the RTD quantizers. The dynamic hysteresis effects of RTD folding circuit are analyzed. From the study of the dynamic hysteresis effect, the limiting factors for folding type A/D converter are investigated and design principles are established. The design tradeoffs for different RTD A/D converters are discussed. Simulations show that the A/D converter can have a sampling rate greater than 5GHz for both types of ADC's. A monolithic 3-bit current-mode A/D converter has been fabricated on InP using multi-well InGaAs/InAlAs RTD's and InGaAs/InAlAs MODFETs and tested. This A/D converter can operate at a 2 GHz sampling rate.; For digital applications, a multi-valued SRAM cell, two multi-valued counters and a multi-valued full adder are proposed. Experimental verification of the circuit concepts are undertaken by breadboarding the circuits using discrete components. The unique features of the RTD folding and hysteresis characteristics are applied to simplify the circuit structure and reduce the power dissipation. The integration feasibility of the multi-valued circuits are improved due to the simple circuit structure developed and the fast switching speed the RTD provides.