Responsible for this page: Lars Wanhammar , firstname.lastname@example.org
Page last update: 2008-05-08
There is a clear trend towards using analog signal processing instead of digital signal processing for wide band signals, particularly in applications with relatively low requirements on SNR. In such cases an analog data path can often be implemented using lower power consumption. Hence we can expect an increasing use of analog filtering. Further there are applications where analog filters are inherently necessary, for example in data converters. A wideband input signal to an A/D converter needs to be bandlimited in order to reduce the aliasing, occuring in the sampling process. The analog output of a D/A converter needs to be filtered by an analog reconstruction filter, to smooth the output spectrum.
Major problems in current design and implementation approaches are how to achieve sufficiently accurate and stable components, large dynamic signal range, and alleviate non-linear effects. These problems are particularly severe in integrated analog filters. We believe that to improve the performance of integrated active filters all the filter design steps need to be cooptimized. A well designed high-performance itegrated filter includes approximation and synthesis problems solved combined with properly chosen implementation techniques.
A large number of active filter realizations need to be investigated and compared with respect to their suitability for integration. Efficient and reliable design tools need to be developed. This will enable fast, reliable and fair comparisons of different designs and techniques.
Analog diplexers and trees of diplexer structures based on LC networks, i.e., analog LC filter banks are investigated with respect to element sensitivity. Dramatic improvement in sensitivity have been demonstrated compart to the "optimal" doubly terminated LC ladder structures. These low-sensitivity filter banks will serve as reference filters, i.e., will be simulated by using active filter techniques. The active filter structure will inherit the sensitivity of the reference filter. Note the low element sensitivity is strongly related to high dynamic signal range, which is one of the main targets in this project.