The Frame-less Membrane: A Novel Technology for THz Circuits

Abstract

A novel GaAs based Schottky diode fabrication process has been developed that enables increased design flexibility and robust implementation of monolithic circuits well into the THz frequency range. The fabrication technique builds on the already demonstrated membrane technology for 2.5 THz mixers [1, 2]. Realizing that the small size of the active devices at these frequencies might not require extensive mechanical support, the thick GaAs frame around the device/circuit has been eliminated. Additionally, increased use of metal beam leads is made to provide not only DC connections, but also RF tuning elements, and handling/support structures. This technology allows designers to rethink their approach to high frequency circuits, by permitting many different types of circuit implementations, which were previously not possible with existing technology. We illustrate the flexibility and potential of this technology by presenting two multiplier circuit designs, a 1.2 THz tripler and a 2.4 THz doubler. Both circuits are based on balanced configuration and utilize split waveguide blocks. These circuits are currently under fabrication and once done will be used for the High Frequency (HIFI) instrument on the Far Infrared and Submillimeter-wave Telescope (FIRST).