A 315 GHz Signal Source in InP-DHBT Technology
Fig.1. Chip photo of the push-push oscillator.
Fig.2. Measured output power spectrum of the push-push oscillator.
Frequencies beyond 300 GHz have been identified as an important frequency range for a great variety of applications. These include future high-speed communications, radar sensors and imaging systems with improved spatial resolution due to a shorter wavelength and large available bandwidth, and spectroscopy. Frequency sources are key building blocks for these systems. Fundamental frequency signal sources are difficult to realize in this frequency range, as they require high device cut-off frequencies. Current signal sources deliver very low power levels and exhibit very low DC-to-RF efficiencies.
Push-push oscillator based signal sources offer an attractive alternative, allowing for lower cut-off frequencies and simplifying THz frequency generation. The advantages of push-push oscillators are that they exhibit decent output power and allow to extend the output frequency close to the maximum oscillation frequency of the transistors or even beyond. They also offer higher tuning bandwidth.
FBH has demonstrated a 315 GHz fixed frequency oscillator with high output power. The MMIC is realized using a 0.8 µm emitter transferred-substrate (TS) InP-DHBT high speed process with an fmax of 320 GHz developed at FBH. The source is based on a push-push topology. The source delivers -10 dBm output power. DC consumption is only 21 mW from a 1.6 volts power supply, which corresponds to 0.5% overall DC-to-RF efficiency. The figure shows a microphotograph of the oscillator chip and the measured output power spectrum, free of spurious signals.
These research activities are funded within the Leibniz Competition project InP transistors for THz power applications exceeding 300 GHz and the MIMIRAWE project No. 50RA1327, jointly funded by the Federal Ministry for Education and Research (BMBF) and the German Aerospace Center (DLR).
Publication
M. Hossain, N. Weimann, V. Krozer, and W. Heinrich, “A 315 GHz Reflection-Type Push-Push Oscillator in InP-DHBT Technology”, in European Microwave Conference (EuMC), London, UK, 2016.