Power-handling Capability of W-band Ingaas Pin Diode Switches

One of the most active research areas in the field of radar applications is the development of collisionavoidance systems (CAS) for automotive industry. The first prototypes of HEMT-based CAS chipsets operating at 77GHz have been recently demonstrated [1]. Such chipsets will greatly benefit from the addition of a monolithic transceiver switch, which would allow using a single antenna for both transmission and reception, and thus greatly reduce the cost of the assembly. PIN switching diodes offer unique advantages over HEMTs such as low ON-state resistance and small OFF-state capacitance combined with high power-handling capability [2,3]. Monolithic switches utilizing InGaAs/InP PIN diodes with excellent characteristics have been reported by the authors at W-band frequencies [4]. InP-based switching PINs offer several important advantages over GaAs-based technology, namely: substrate compatibility with high-performance InP-based HEMTs, low DC power consumption, and low ON-state resistance due to high electron mobility and small bandgap of InGaAs. However, the smaller bandgap of InGaAs also manifests itself in earlier onset of self-biasing effects and a smaller breakdown voltage, which affects their power handling. In this work the power-handling capability of InGaAs PIN diodes is reported and compared to that of GaAs PIN diodes. The trade-off between power handling, high frequency performance, and bias conditions is considered. W-band InGaAs PIN diode monolithic switches were fabricated using coplanar-waveguide technology, and their large-signal characteristics measured using a W-band load-pull characterization system are reported for the first time.