Transition metal dichalcogenide MoS2 field-effect transistors for analog circuits: A simulation study

As the scaling of silicon MOSFET approaches to its physical limit, research efforts have been made in exploring alternative devices. In this work, fundamental design metrics of analog circuits using two-dimensional transition metal dichalcogenide (2D-TMD) molybdenum disulfide (MoS2) transistors are systematically investigated and compared with the state-of-the-art silicon MOSFETs. Based on analytical derivation and numerical simulations, we find that the drain current efficiency and channel length modulation factor of MoS2 transistors are less relevant to the channel length. Under a condition of the same bias current and device geometry, intrinsic gains of MoS2 transistors are at least 12.3 dB higher than silicon MOSFETs. Three case studies are performed to investigate the use of MoS2 transistors in analog circuits. The key performance indicators of operational amplifiers, such as circuit area, power consumption, voltage gain, gain-bandwidth product (GBW), and tolerance to random process variation are studied. Simulation results demonstrate that MoS2 based analog circuits lead to significant improvement in performance and are more resilient to process variation. For example, when designing two-stage common source amplifiers, under an iso-GBW condition, MoS2-based design can increase voltage gain by at least 72%, save circuit area by 45-60%, and reduce power consumption by 11-58% than silicon-based designs.