The concept of the DOTFIVE project stems from the competitive race existing in semiconductor research to achieve individual devices and integrated circuits with higher operating speed allowing realization of new applications in new regions of the electromagnetic spectrum.
Applications in the emerging high-frequency (h.f.) markets more and more use SiGe components for cost reasons. Current state-of-the-art research and development is taking place primarily in data communication and radar systems at 24, 60, and 77 GHz [Floy06, Kata07, Haji05]. For instance, IBM has just demonstrated that its state-of-the-art SiGe HBT technology has the potential to play a major role in high-volume consumer electronic markets by proving the feasibility of 2-Gbps uncompressed HDTV transmission over a 60-GHz SiGe HBT radio link [Kata07, Pfei06a, Floy06].
The main objective of the DOTFIVE project is to demonstrate the realization of SiGe Heterojunction Bipolar Transistors (HBTs) operating at a maximum frequency close to 0.5 THz (500 GHz) at room temperature, and evaluate the achievable performance of integrated mmWave circuits using those HBTs. Further important objectives are:
To identify the most important effects and to incorporate an adequate description in a compact model.
To develop new parameter extraction methods and to provide a unified set of test structures.
To provide clear guidelines on high-frequency characterization, de-embedding methods and test pad design.
The main drawbacks in existing designs, which operate typically at frequencies up to a third of the transit frequency fT, are the necessary high bias currents leading to a power dissipation of several watts per radar chip and a limited achievable noise figure (NF) in each building block. The former disadvantage results in additional cooling effort, which implies costly packaging and mounting procedures. The latter directly influences the overall performance, as the total signal-to-noise ratio (SNR) in homodyne systems is directly limited by the NF of the (active) mixer. Thus, technologies with higher fT can directly lead to improved automotive radar systems with higher performance at lower power consumption, which increases road safety and energy budget. With an increased fT completely new and highly integrated microwave sensor systems are feasible.
However, until recently, this spectral region has resisted attempts to broadly harness its potential for everyday applications. This led to the expression THz gap, loosely describing the lack of adequate technologies to effectively bridge this transition region between microwaves and optics, both readily accessible via well developed electronic and laser-based approaches. THz technology is an emerging field which has demonstrated a wide-ranging potential. Extensive research in the last years has identified many attractive application areas and has paved the technological path towards broadly usable THz systems. THz technology is currently in a pivotal phase and will soon be in a position to radically expand our analytic capabilities via its intrinsic benefits. In this context, DOTFIVE is planned to establish the basis for fully integrated cost efficient electronic THz solutions.