The technical target of the MIXMODEST project is to develop design techniques that permit the implementation of mixed signals systems in the most advanced 0.35µm and 0.25µm deep sub-micron digital CMOS technology. Embedding advanced analogue functions such as front-ends, converters and back ends in complex digital integrated circuits is today based on extra analogue technology options that yield devices and components with reduced tolerances, such as accurate resistors and capacitors. These mixed signal technologies lag one generation behind of the most dense mainstream digital technology and therefore force to implement quite complex digital circuits in a less efficient manner. This constitutes a serious economical drawback for mixed signal systems that tend to have a relatively large area of digital circuitry (90%) and small area on analogue (10%). 

The final goal will be to achieve, in the next generation digital technology, the same analogue performance while keeping the same area for the analogue part and shrinking the digital by 50%. The main constraint is the lack of precision elements such as matched capacitors and resistors. Capacitors and resistors that can be made available in the digital technology will have an accuracy as low as 30% compared to 5% for analogue processes, while the matching behaviour is normally not known. Next to the less accurate devices, the main limitation is also the low power supply down to 2.4V as found in 0.25µm CMOS technology. This reduces the effective voltage and requires special measures to be taken to achieve the signal to noise ratio, including the effects of cross talk. The problem will have to be tackled by the introduction of innovative techniques on all levels of a design starting from the development and thorough characterisation of structures for active devices and components, over circuit techniques such as differential and current mode, up to architectures including self-calibration.

The whole approach will be demonstrated by means of real converter designs and a high speed xDSL driver.