Millimeter-Wave MMIC Signal-Power Generation and Amplification
Fig. 1 Large-signal performance of medium power amplifier at 90 GHz
Fig. 2 Small-signal performance of the medium power amplifier in Fig. 1
Fig. 3 Bandwidth characteristic of the medium power amplifier of Fig. 1
Signal power generation and amplification at W-band frequencies and beyond is key for various application areas, such as medical technology, non-destructive materials testing, radar, security, and space. To meet this increasing demand, FBH has developed and realized solid-state power amplifiers (SSPA) using its in-house high-speed InP transfer-substrate DHBT process with transit frequencies beyond 350 GHz. The target frequency range for the SSPA is 75 – 200 GHz with high output powers of 100 mW and high power-added efficiency. The realized SSPAs are compact and robust in operation and allow for easy integration into waveguide or planar front-end modules. The InP transfer-substrate DHBT offers a small-signal gain of 8 dB per single-stage single-transistor in its simplest common-emitter (CE) configuration at the upper W-band edge. A flip-chip technology with appropriate heat-sinking has also been developed.
Medium power amplifiers with 10 dB gain and > 15 dBm output power across the 80 – 100 GHz band have been demonstrated. Higher output powers with small-signal gain of 15 dB and output powers approaching 100 mW have been achieved, but operating currently in a narrower bandwidth. Further circuit design developments have demonstrated similar output powers at higher frequency while maintaining the total emitter area unchanged. Realization of these circuits is under way. A further focus is on the design of high efficiency SSPAs with efficiencies exceeding 30 % at frequencies beyond W-band.
G-band power amplifiers in CE configuration and G-band doublers with PA, based on InP HBTs, have also been implemented in the recently developed wafer-level hetero-integrated InP-on-BiCMOS technology platform. This platform is offered in a collaboration with the IHP (Innovations for High Performance Microelectronics) in Frankfurt/Oder. For a fully integrated source with doubler an output power of 7 dBm at 164 GHz center frequency was demonstrated. A stand-alone G-band doubler with PA has achieved peak output powers of 10 dBm, with broadband output power beyond 6 dBm over the entire G-band.
In addition, more explorative activities consider high-gain high-output power PAs using cascode structures beyond G-band and high-efficiency compact topologies. FBH has also developed wafer-level heat-spreading technologies, which have demonstrated a decrease of the device thermal resistance by a factor of two. These devices are tested now in high-power PAs aiming at even higher output powers.
The InP-on-BiCMOS technology platform is accessible via the IHP foundry service to external customers including a dedicated design kit for the InP process. Measurement and characterization facilities at FBH for small-signal and large signal characterization are available up to 500 GHz.
Publication:
T. Al-Sawaf, M. Hossain, N. Weimann, O. Krüger, V. Krozer and W. Heinrich, "G-band Frequency Doubler based on InP Transferred-Substrate Technology," accepted for presentation at the European Microwave Week 2015.