Implementation of a Two-Channel Maximally Decimated Filter Bank using Switched Capacitor Circuits

The aim of this paper is to describe the implementation of a two-channel filter bank (FB) using the switched capacitor (SC) technique considering real properties of operational amplifiers (OpAmps). The design procedure is presented and key recommendations for the implementation are given. The implementation procedure describes the design of two-channel filter bank using an IIR Cauer filter, conversion of IIR into the SC filters and the final implementation of the SC filters. The whole design and an SC circuit implementation is performed by a PraCAn package in Maple. To verify the whole filter bank, resulting real property circuit structures are completely simulated by WinSpice and ELDO simulators. The results confirm that perfect reconstruction conditions can be almost accepted for the filter bank implemented by the SC circuits. The phase response of the SC filter bank is not strictly linear due to the IIR filters. However, the final ripple of a magnitude frequency response in the passband is almost constant, app. 0.5 dB for a real circuit analysis

Analysis and Synthesis of the Digital Structures by the Matrix Method

This paper presents a general matrix algorithm for analysis of digital filters. The method proposed in this paper allows not only the analysis of the digital filters, but also the construction of new structures of the canonic or non-canonic digital filter. Equivalent filters of different structures can be found according to various matrix expansions. The structures can be calculated even from transfer function or from state-space matrices and with the additional advantage of requiring minimum number of shifting elements. Traditional research methods are not able to construct the system with a minimum of the shifting operations

Finite Word-Length Effects in Digital State-Space Filters

The state-space description of digital filters involves except the relationship between input and output signals an additional set of state variables. The state-space structures of digital filters have many positive properties compared with direct canonical structures. The main advantage of digital filter structures developed using state-space technique is a smaller sensitivity to quantization effects by fixed-point implementation. In our presentation, the emphasis is on the analysis of coefficient quantization and on existence of zero-input limit cycles in state-space digital filters. The comparison with direct form II structure is presented