Mehmet Kaynak

SiGe-BiCMOS based technology platforms for mm-wave and radar applications

In this work different SiGe-BiCMOS based technology platforms for mm-wave and radar applications are presented. Based on the evolution of IHP BiCMOS technologies the performance improvement for SiGe-heterojunction bipolar transistor (HBT) in the past decades in comparison to scaled RF-CMOS technologies is shown. We depict that an increase of the processing effort of only 35% deliver a SiGe-HBT device performance improvement of >170% compared to IHPs first high-speed HBT generation. Moreover the co-integration of new modules with the SiGe-BiCMOS baseline technology is reviewed. The monolithic integration of an additional RF-MEMS switch module is shown and we discuss different packaging approaches for the integrated device. Furthermore a SiGe-BiCMOS/InP-bipolar heterogeneous integration platform is presented. All shown technologies had proven their usefulness for radar applications and different examples from F-band up to the 240 GHz range are reviewed.

Silicon photonics for 100 Gbit/s intra-data center optical interconnects

We report on an ultra-compact co-integrated transmitter and receiver in SiGe BiCMOS technology for short reach optical interconnects. A fully integrated EPIC transceiver chip on silicon photonics technology is described. The chip integrates all photonic and electronic devices for an electro-optic transceiver and has been designed to be testable on wafer-scale. A node-matched diode modulator based on carrier injection is a key building block in the chip design. Its operation performance is presented with respect to insertion loss, signal-to-noise-ratio and power consumption at a 25.78125 Gbit/s in NRZ operation. A novel SiGe based photodetector exhibits a -3 dB bandwidth of up to 70 GHz and a responsivity of >1 A/W. Details are given about the process technology of co-integration of photonic and electronic integrated circuits using both silicon-on-insulator and bulk silicon. The implemented co-integration process requires only few additional process steps, leading to only a slight increase in complexity compared to conventional CMOS and BiCMOS baselines.

Pixel resistance optimization of a Si0.5Ge0.5/Si MQWs thermistor based on in-situ B doping for microbolometer applications

The state-of-the-art microbolometers are mainly based on polycrystalline or amorphous materials, typically Vanadium oxide (VOx) or amorphous-Silicon (a-Si), which only have modest temperature sensitivities and noise characteristics. The properties of single crystalline SiGe/Si multi quantum wells (MQWs) have been proposed as a promising material1. Particularly, SiGe/Si MQWs structure with high Ge concentration is expected to provide very high temperature coefficient of resistance (TCR) values between 6 to 8% 2. Although SiGe/Si MQWs structure as a thermistor material is extremely promising, difficulty of defect free deposition and high sheet resistance of high Ge concentrated SiGe layers are the two main bottlenecks of this approach. In this work, a very high TCR of -5.5 %/K is achieved for SiGe/Si MQWs including 50% Ge with an acceptable noise value of 2.7 x 10-13 V2/Hz at 10 Hz. The initial pixel resistance of 3 period of SiGe/Si MQWs with 50% Ge concentration is measured as 21 MΩ, which might not be compatible with the ROIC design. By the optimization of insitu Boron (B) doping level in SiGe layers of the MQW stack, 210 kΩ for 25 x 25 μm2 pixel size is achieved. The optimized B doping density of ~1 x 1018 cm-3 in SiGe wells did not cause any significant change in the TCR value whereas the 1/f noise performance is even enhanced due to the in-situ doping process and measured as 2.9 x 10-14 V2/Hz at 10 Hz.

60 GHz planar filters and transmission lines characterization in 0.25µm BiCMOS technology

In this article, three main aspects of passive millimeter-wave integrated filter realization are exposed. Firstly, the importance of the transmission line choice is discussed by comparing microstrip and coplanar waveguide (CPW) in BiCMOS 0.25µm technology. 50-Ω transmission lines exhibit similar losses around 0.6 dB/mm at 60 GHz. Secondly, two filter topologies, a dual-behavior resonator based filter and a dualmode ring based filter, are compared in terms of insertion losses, surface area and out-of-band rejection. They are both designed using microstrip lines and exhibit a similar 3dB fractional bandwidth (FBW3dB) around 12% with a 60 GHz center frequency. Finally, a miniaturization method is presented using Metal-Insulator-Metal (MIM) capacitive loading. A loaded filter is then realized and characterized. Similar electrical performance are demonstrated with a size reduction factor of 2.3.

Characterization of CPW transmission lines and 60GHz DBR Filters in 0.25μm BiCMOS technology

In this paper, CPW transmission lines and Dual Behavior Resonator (DBR) filters implemented in SiGe BiCMOS 0.25-μm technology are presented. Three CPW lines, whose characteristic impedances are between 35 Ω and 80 Ω, exhibit attenuation loss lower than 0.7 dB/mm at 60 GHz. Two DBR filters based either on microstrip or on CPW transmission lines are compared. The filter with microstrip lines has already been measured and exhibits 11.6% of 3-dB relative fractional bandwidth (FEWmb) and 5.4 dB of insertion losses at 60 GHz. The second one is supposed to have similar performance with lower insertion loss (3.3 dB) and its measurement will be available for the conference.