This paper presents an efficient and simple method for designing multiplierless very sharp Hilbert transformers. We use identical low-order Hilbert transformers as subfilters and the tapped cascaded interconnection of the subfilters is provided by a simple prototype filter. In order to obtain an overall multiplierless design, the rounding is applied to the coefficients of prototype filter and all subfilters. Additionally, we propose to employ the Pipelining/Interleaving (P/I) technique and the Common Subexpression Elimination (CSE) method for savings in the number of adders.
Finite Impulse Response (FIR) Hilbert Transformers (HTs) have a high complexity when they are designed with a very sharp transition band and a small ripple. This complexity is dominated by multipliers, the most expensive elements in a digital filter. Frequency Transformation (FT) is a technique to design FIR filters with repeated simple identical subfilters, which can be used to reduce the overall number of distinct multipliers. In this paper an efficient structure based on the Pipelining Interleaving (PI) technique, where only one time-shared subfilter is employed, is proposed for FT-based HTs. The overall number of required multipliers is the same as the number of distinct multipliers used in the FT-based design. It is shown by mean of examples that the HTs designed with the proposed structure require less number of multipliers than previous FT-PI-based existing methods.
A cascaded integrator-comb (CIC)-based decimator is proposed, which consists of an area-efficient structure aided with an embedded simplified Chebyshev-sharpened section. Taking traditional CIC filters as a reference, the proposed scheme fulfils two important goals: (i) it improves the worst-case aliasing rejection and (ii) it preserves a low-complexity design that requires fewer hardware resources and consumes less power. The proposed system exhibits regularity, a desirable characteristic not present in other CIC-based recent methods from literature that have pursued the same goals.
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Novel finite impulse response architectures for wide passband droop compensation of cascaded integrator-comb filters are presented. Compared with the recent wide-band compensators introduced in the literature, the proposed systems achieve better passband droop correction with lower power dissipation, lower hardware utilisation and higher maximum frequency of operation, as validated with post-place-and-route information from FPGA-based implementations.
This paper presents an efficient design of lowcomplexity wide-band compensators to improve the passband characteristic of Cascaded Integrator Comb (CIC) filters. The proposed compensators are designed using the amplitude transformation method recently presented in a companion paper. This work also provides a simple formula to obtain the coefficients of the compensator. Design examples and comparisons were addressed to show that the proposed compensation filters have better frequency characteristics compared to other wide-band compensators recently presented in the literature.
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