Digital Auto-Tuning for Center Frequency and Q-Factor of Gm-C Band-Pass Filter

Abstract

This paper describes digital auto-tuning schemes for second-order Gm-C bandpass filters which are suitable for fine CMOS implementation. We propose a switched Gm-C analog filter and two digital tuning schemes: a center frequency tuning scheme using the phase information and a Q factor tuning scheme using the magnitude information. We present circuits, describe their operations, and present SPICE simulation results.

Cellulose Based Cryogels as Adsorbents for Organic Pollutants

“…However, HPMC-CNC-SO 4 15% and HPMC-CNC 15% presented higher ρ ap values (0.026 AE 0.001 g cm À3 ), because the CNC content in the cryogels increased and the density of CNC (1.6 g cm À3 ) [8] is higher than that of HPMC (1.3 g cm À3 ). Similar density values were reported for cellulose cryogels made of waste newspaper dissolved in 1-allyl-3methyimidazolium chloride and subsequent solvent exchange with tert-butanol, [27] cellulose nanofibril cryogels prepared by freeze-drying, [28] composite cryogels based on dialdehyde nanocellulose fibers and collagen. [29] Figure 4a and b show the sorption curves of hexane and water, respectively, by HPMC, HPMC-CNC-SO 4 5%, HPMC-CNC-SO 4 15%, HPMC-CNC 5%, and HPMC-CNC 15% cryogels at The θ values were determined for water in contact with HPMC, HPMC-CNC-SO4 5%, HPMC-CNC-SO4 15%, HPMC-CNC 5%, or HPMC-CNC 15% cryogels ranged from (74 AE 1) to (81 AE 1) and there was no statistically significant difference among them (p ¼ 0.50).…”

“…youtube.com/watch?v=SOhz_TGWTaU). Compressed cellulose nanofibril (CNF), [27] cellulose nano/micro-fibril cellulose (NFC/ MFC), [31] CNC, and CNF [32] aerogels also recovered quickly their original shape in water, but not in ethanol or organic solvents. [31,32] Upon exposing the compressed aerogels/cryogels to water, the polymer chains swell, disrupting some of the H bonding among the cellulose hydroxyl groups, expanding the matrices and recovering their original shape.…”