A new resonant-tunnel diode-based multivalued memory circuit using a MESFET depletion load

A resonant-tunnel-diode-based (RTD-based) multivalued memory (MVM) circuit using a depletion-load MESFET is described. Compared with the commonly used resistor load in multivalued logic (MVL) circuits, this circuit design offers better noise margins, lower power dissipation, and easier integration. SPICE was used to simulate a three-state memory circuit, functioning as a MVL cell and consisting of a series connection of two RTDs and a MESFET depletion load. It is shown that the simulated multipeak I-V curve for this MVM cell is in good agreement with the measurement results from the two discrete RTDs connected in series. The signal write and read operations for this MVM circuit are also successfully simulated, and these operations were reliable and showed fast response. Some important effects on the MVM circuit due to the parasitic resistor and capacitor in the RTD are discussed. This MVM cell structure can be easily extended to implement more states in a memory circuit.<>