Design of Two-Stage Comb-Based Decimation Filter with High Aliasing Rejection and Low Passband Droop

Abstract

This paper presents a simple method for the design of comb-based decimation filter with a high aliasing rejection and low passband droop. The method is based on the application of the mathematical result on zeros of symmetric polynomials on the unit circle. The application of this result leads to the introduction of the four additional single zeros into comb folding bands, where aliasing occur. As a result, the folding bands become wider and the aliasing rejection is increased. The passband droop is compensated by a simple compensator who works at low rate. The comparisons with the most recent methods from literature confirmed the advantages of this proposal regarding magnitude responses and the required complexity.

Decimation filters with minimum number of additions per output sample

“…Table 4. Decimation factor R, maximum passband deviation, δ p , minimum folding-band attenuation, γ s , and number of additions per output sample, A, of decimation filters in [6] and proposed filters compensated with compensators in [8] with coefficients c Improvements are highlighted in bold.…”

“…Both filters utilize passband droop compensators. Table 4 shows maximum passband deviation, minimum folding-band attenuation, and the number of APOS of the cascades designed with ω p = 0.5π /R and various R. Two examples of the proposed filters are provided for the comparison with each filter from [6]. In all cases, the proposed cascades exhibit smaller number of APOS, higher foldingband attenuations, and smaller passband droops.…”

“…Example 4: Our last example compares the proposed filters and the filters from [6]. Both filters utilize passband droop compensators.…”

“…Such an approach is utilized in multistage decimation filters. State-of-the-art methods for their design usually consider two stages [2][3][4][5][6]. This Letter proposes a framework for the design of multistage decimation filters with minimum number of additions per output sample (APOS).…”

Design of Decimation Filter With Improved Magnitude Characteristic and Low Complexity

“…Similarly, in [13], the cascade of two simple filters derived from symmetrical polynomials was presented to introduce additional zeros into comb-folding bands. This approach was improved in a two-stage structure with a compensated passband, as proposed in [14]. The method in [15] combines the simple filters from [11] and, [13] to increase the widths and attenuation of the folding bands, resulting in increased complexity.…”