Novel multiple-selected and multiple-valued memory design using negative differential resistance circuits suitable for standard SiGe-based BiCMOS process

摘要

A novel multiple-selected and multiple-valued memory (MSMVM) design using the negative differential resistance (NDR) circuits is demonstrated. The NDR circuits are made of Si-based metal-oxide-semiconductor field-effect-transistor (MOS) and SiGe-based heterojunction bipolar transistor (HBT). During suitably designing the parameters and connecting three MOS–HBT–NDR circuits, we can obtain the three-peak current–voltage (I–V) curves with different peak currents in the combined I–V characteristics. For the traditional resonant-tunneling-diode (RTD) memory circuit, one can only obtain four-valued memory states using a constant current source to bias the three-peak NDR circuit. However in this paper, we utilize two switch-controlled current sources to bias the three-peak NDR circuit at different current levels. By controlling the switches on and off alternatively, we can obtain the four-valued, three-valued, two-valued, and one-valued memory levels under the four different conditions. Our design is based on the standard 0.35 μm SiGe BiCMOS process.