Details (HF Design Technologie für präzise analoge IP-basierte Front-End Lösungen in höchstintegrierten Datenübertragungs-Systemen)
The contribution of the Competence Center on Integrated Circuits in Communications to the DETAILS project focuses on the evaluation of circuit topologies with regard to the generation of scalable RF-blocks for use in a system-oriented design approach. These so called RF IPs simplify and consolidate the design and the simulation of the overall system. A major issue is the determination of appropriate tuning elements within the function block to achieve specific performance characteristics and the definition of the corresponding parameter matrix. The parameter matrix is used for a system-oriented description of the circuit using a high-level description language. Especially the design, the modeling and the optimization of spiral inductors have become a bottleneck of a system-oriented design flow that requires accurate and scalable models. Accurate modeling of lumped element reactances is a very complex and demanding issue as it includes layout aspects like size, losses and parasitic coupling together with substrate impacts. Moreover, the validate regime of an equivalent circuit model has to be carefully evaluated for use in a system-oriented design approach. The Details project highlights utilization of simulation tools for the design of compact spiral inductors and validation of the equivalent circuit model by comparison of measured and simulated data. The evaluation of the model accuracy and the definition of a valid operating regime of the model is a major step towards a systemoriented design approach.
In the past numerous designs of broad-band amplifiers with little emphasis on their noise figure have been presented. The major challenge in designing low noise amplifiers for UWB systems is to simultaneously broaden the operating frequency range in terms of gain, noise matching and linearity. Commonly used techniques in designing broad-band amplifiers are feedback, inductive and capacitive peaking methods or distributed amplification. We have designed a three-stage amplifier with a common emitter stage which is succeeded by an emitter follower and an additional common emitter stage. Both common emitter stages use series feedback with capacitive emitter peaking. Global shunt feedback is applied between the first and second stage. The parasitic input capacitance of the final common emitter stage is partly compensated by an inductive transmission line between the second and third stage. All stages are DC-coupled, which results in a flat frequency response down to DC. The amplifier exhibits an extremely low noise figure together with a very small occupied die area of 0.44mm x 0.38mm. A microphotograph and measurement results of the realized low noise amplifier are shown in the attached figures.
The ultra-wideband (UWB) research topic includes the realization of integrated UWB receivers and transmitters that are realized monolithically on Silicon. Advantages of UWB systems compared to narrow-band communication systems include an extremely low power spectral density, an inherent low system complexity and low power consumption. UWB is an ideal candidate for biomedical applications such as radar-like diagnostic tools or communication links with implanted sensors. In practical realization, the key element of any I-UWB system is the impulse generator. An example of an realized impulse generator is shown in the figures.