Electrical computers: arithmetic processing and calculating – Electrical analog calculating computer – Particular function performed
Reexamination Certificate
1998-06-26
2001-07-24
Mai, Tan V. (Department: 2121)
Electrical computers: arithmetic processing and calculating
Electrical analog calculating computer
Particular function performed
Reexamination Certificate
active
06266689
ABSTRACT:
The present invention relates to a complex switched capacitor filter and a designing method for such a filter.
BACKGROUND
Real switched capacitor filters are well known citation [1] and have the advantage that they can be integrated, can handle analog input signals, are small in size and have low power dissipation. Recently there has been more and more interest in complex filters, i. e. filters having two inputs and two outputs for receiving a complex input signal and delivering a filtered complex output signal. One example of such filters is complex bandpass filters, which are useful in, for example, radio communication applications. Thus, it would be desirable to be able to design a filter for the complex domain having all the advantages of a real switched capacitor filter.
SUMMARY
An object of the present invention is to provide an extension of a switched capacitor filter into the complex domain while maintaining all the advantages of the corresponding real filter and a method to design such a filter.
This object is achieved with a filter and designing method.
Briefly, the present invention forms a complex switched capacitor filter by starting with an analog baseband prototype filter having the required filter specifications. This prototype filter is transformed into a corresponding real switched capacitor filter. Finally the real filter is transformed into a complex filter, preferably by frequency shifting, to obtain the complex switched capacitor filter.
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Franca, “Efficient Switched-Capacitor Implentation of Linear Phase FIR Decimators”, Electronics Letters Sep. 28th 1989, vol. 25 No. 20, pp. 1402-1403.*
Hurst et al, “Finite Impulse Response Switched-Capacitor Decimation Filters for the DSM D/A Interface”, 1989 IEEE.*
Iwakura, Hiroshi, et al., “Design of Complex Digital Filters Using Frequency Transformation,” IEICE Transactions, vol. E 74, No. 12, pp. 3930-3934 (1991).
Liu, Q. et al., “Switched Capacitor Implementation of Complex Filters”, IEEE International Symposium on Circuits and Systems, vol. 3, 19. pp. 1121-1124, 1986.
Jantzi, S. et al. “A Quadrature Bandpass &Sgr; &Dgr; Modulator for Digital Radio”, IEEE International Solid-State Circuits Conference, vol. 40, pp. 216, 217, 460, Feb. 1997.
Smolka, G., “Switched-Capacitor Bandpass Filter Bandpassed on Simulation of Canonical Reactance Sections”, IEEE Journal of Solid-State Circuits, vol. sc-19, No. 3, pp. 360-367, Jun. 1984.
Zzerev, Antol, “The Catalog of Normalized Lowpass Filters”, Handbook of Filter Synthesis.
Signell, Svante, “Design of Parasitics-Insensitive bilinear Switched-Capacitor Filters a Matrix Conversion Method”, Dec. 1981.
Shier Thorsten
Signell Svante
Burns Doane Swecker & Mathis L.L.P.
Mai Tan V.
Telefonaktiebolaget LM Ericsson (publ)
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