A novel design of a fully programmable switched current filter

Abstract

In this study, the design of a programmable infinite impulse response switched current (SI) filter is presented. The characteristics of the filter are fully programmable by simply varying the values of out-of-chip DC current sources. The programmable switched current filter mainly consists of SI delay cells and SI multipliers. A high-performance class AB grounded gate SI memory cell is used as a basic building block. Spice simulation results are presented to show the functionality of the programmable filter.

Switched-current filter structure for synthesizing arbitrary characteristics based on follow-the-leader feedback configuration

“…Simply, M i can be realized by an NMOS transistor with associated switch closed on phase ϕ i [10], the so-called second generation SI memory cell. But, for cancelling non-ideal behaviour, several enhancement techniques such as cascode and S 2 I can be used [10][11][12][13][14][15][16]. Particularly, when S 2 I technique is selected to realize M i and J, Fig.1(a) can be specialized to the structure used in [17,18].…”

“…Also, SI filter has been considered as an alternative to switched-capacitor (SC) filter in mixed signal systems, owing to the characteristic of compatibility with digital VLSI technology. To date, several competitive SI basic cells have been presented [10][11][12][13][14][15][16]. However, the generation of SI filter structure has not been investigated well so far, which has greatly impeded the widespread application of SI technique.…”