Ion-implanted GaAs MESFET MMICs for 77-GHz automotive radar

Several commercial markets for monolithic millimeter-wave integrated circuits (MMICs) have emerged in recent years. In particular, significant developments have occurred in Ka-band short-haul digital radio and W-band automotive collision-avoidance radar. Such high-volume markets demand manufacturing solutions capable of providing large quantities at minimum cost. While ion-implanted metal-semiconductor field-effect transistor (MESFET) technology may be the logical choice in terms of cost, devices fabricated in other technologies have outperformed MESFETs at millimeter-wave frequencies. MESFETs are a viable alternative to high-electron-mobility transistors (HEMTs) at Ka-band, but present efforts at W-band focus entirely on epitaxial HEMT or heterojunction bipolar transistor (HBT) technologies for low-noise and power amplifiers and epitaxial Schottky diode structures for mixers. These expensive epitaxial technologies were originally developed and are required for current and future millimeter-wave military applications. However, a high-performance MESFET process may be a suitable low-cost alternative for high-volume commercial applications.; This dissertation summarizes the design and performance of a set of MMICs fabricated at the University of Illinois in a 0.12-μm direct ion-implanted GaAs MESFET process. The circuits are suitable for insertion into a 77-GHz automotive radar system. This work develops non-linear, linear and noise models for the MESFET and Schottky diode and synthesizes models for a variety of coplanar passive components. All of the models are verified with comparisons to measured data through W-band. This work then presents measured and simulated performance characteristics of the MMICs. A three-stage amplifier exhibits 8 dB of gain, and each diode and FET-based mixer exhibits less than 15 dB of conversion loss at 77 GHz. These results demonstrate the potential of ion-implanted MESFET technology at millimeter-wave frequencies.