FBH research: 30.05.2018

Ultra-broadband, high-power distributed amplifier in InP DHBT technology

Chip photograph of the amplifier
Fig. 1: Chip photograph of the amplifier
Simulated (solid) and measured (dotted) S-parameter and stability factor vs. frequency
Fig. 2: Simulated (solid) and measured (dotted) S-parameter and stability factor vs. frequency

Ultra-broadband, highly linear amplifiers are fundamental blocks of high-speed optical drivers, modulators and transceivers as well as measurement systems. Apart from uniform gain response throughout the bandwidth, uniform RF output power over the frequency is an important merit. In addition, the amplifiers in such systems should not introduce deviation from linear phase. This work takes all these important parameters into account, reporting a stable amplifier with high linearity and low deviation from linear phase over a large bandwidth from DC to 95 GHz. In addition, the amplifier exhibits superior power capabilities to other technologies with equivalent bandwidth.

Recently, this report was published at GEMIC 2018 conference in Freiburg, Germany. The reported circuit is based on a five-cell distributed cascode topology. FBH’s in-house transferred substrate InP/GaAsSb/InP DHBT was used to fabricate these 0.8 × 6 µm single finger transistors. A small signal gain of 12 dB was obtained between DC and 95 GHz with the reflection coefficients (S11 and S22) below -10 dB. The deviation from linear phase is only ±10 degrees from low frequency up to 80 GHz. The measured 1 dB compression point for the output power is observed from 5 to 80 GHz with a nominal value of 9.5 dBm with a variation of ±0.5 dB over the measurement data. Importantly, the circuit only consumes 126 mW of DC power. Moreover, the simulated noise figure of the circuit is 7 dB with a variation of ±0.5 dB from 0.5 – 90 GHz. These aforementioned merits make the circuit an attractive choice for components in high-speed, ultra-low power optical transceivers.

The authors are indebted to Helmholtz Research School on Security Technologies (HRSST) and DLR (German Aerospace Center) for PhD student funding. Furthermore, part of the work was funded by the Leibniz project ‘InP THz HBT’ and EU FP7 CIG ‘THzPowerElectronics (333858)”.

Publication

T. Shivan, N. Weimann, M. Hossain, T. Johansen, D. Stoppel, S. Schulz, O. Ostinelli, R. Doerner, C.R. Bolognesi, V. Krozer, W. Heinrich, "A 95 GHz Bandwidth 12 dBm Output Power Distributed Amplifier in InP-DHBT Technology for Optoelectronic Applications", 11th German Microwave Conference (GeMiC 2018), Freiburg, Germany, Mar. 12-14, ISBN 978-3-9812668-8-7, pp. 17-20 (2018).