Robert K. Henderson

A methodology for integrated ladder filter design

The design procedures for integrated ladder filter design by operational simulation are regularized in terms of matrix operations. This analysis provides a systematic framework for the derivation of standard circuits such as leapfrog and coupled-biquad as well as several novel structures. Each circuit is seen to belong to a certain family, dependent on the type of matrix factorization used. A detailed comparison of the properties of the different structures is undertaken for a range of filter specifications, demonstrating that ladder filters offer good solutions to several difficult filtering problems. The methods are applicable to all active filter technologies including active-RC and switched capacitor. >

Matrix methods for switched-capacitor filter design

A matrix-form description of switched-capacitor (SC) filter networks is introduced. It offers a unified approach to the design of many different categories of filter specification and structure. By the application of matrix transformations, most notably LU factorization, filter structures simulating passive networks are derived. One such design eliminates the unswitched capacitive loops of leapfrog filters. Matrix design methods have been implemented in a software package for SC, active-RC, and digital filters.<<ETX>>

Decakis(phenylthio)benzophenone: A Representative of a Novel Class of Host Molecule Comprised of Two Linked Persubstituted Aromatic Cores

Abstract The title compound 1, prepared by reaction of decafluorobenzophenone 5 with PhSNa in DMEU, forms a 1:1 adduct with DMF; in this adduct the molecules central V-shaped twin core possesses approximate C 2 symmetry, though this does not extend to the molecular periphery owing to the ababababab side-chain orientational distribution [a, above core benzene plane; b, below]. The adduct crystallizes in the monoclinic space group P2 1/c with a = 16.559(3), b = 23.233(5), c = 18.640(4), A, β = 114.49(3)° and Dc = 1.363 gcm−3 for Z = 4. The refinement is based on 4621 observed reflections and gives a final R value of 0.069.

A new filter approximation and design algorithm

Two complementary algorithms that apply Newtons method to approximation and passive ladder filter design are presented. Amplitude responses with a specified weighting or derivative value can be computed. The numerical ill-conditioning of conventional ladder synthesis methods is avoided by an extended version of H.J. Orchards (1985) algorithm. The techniques have been used in a filter compiler, and many practical difficulties are covered.<<ETX>>

Design of a switched-capacitor filter for voice band signals

Conventional SC realizations of wideband filters demand large capacitance spread and exhibit serious sensitivity problems. The UL-LU structure is a ladder type simulation which demonstrates superior sensitivity performance and maintains low capacitance spread. Results from fabricated devices confirm the predicted properties.<<ETX>>

FRACTIONAL FLOW RESERVE (FFR) VERSUS ANGIOGRAPHY IN GUIDING MANAGEMENT TO OPTIMIZE OUTCOMES IN NON-ST ELEVATION MYOCARDIAL INFARCTION (FAMOUS - NSTEMI) HEALTH ECONOMIC ANALYSIS

An economic model was developed to compare the medical resource cost and health outcome effects of physiology-guided management with FFR compared with standard angiography-guided management in patients with non-ST elevation myocardial infarction based on participants British Heart Foundation FAMOUS-

Hexakis(mercaptomethyl)benzene: a Structure Possessing Well Ordered Homodromic [SH⋯S]6 Interactions

In the molecular crystal of the title compound, 1,2,3,4,5,6-phenylhexakis(methanethiol), C12H18S6, an intermolecular [SH]6 grouping around a point of overline{3} symmetry is found between molecules which are stacked infinitely along the c-axial direction.

1,2-Bis[2,3,4,5,6-pentakis(phenylthio)phenyl]ethane

In its molecular crystal the title compound, C74H54S10, has an anti conformation about the central C—C bond. The molecule is centrosymmetric and exhibits regular alternation of the phenylthio side-chain units above and below the mean plane of the 14u2005C atoms of the diphenylethane skeleton. In contrast, the ethylene link unit has a syn relationship with respect to the phenyl groups of the phenylthio substituents in the ortho positions.

A unified approach to the design of canonical integrated ladder filters

A method is introduced for designing stable, active integrated ladder filters with canonic numbers of op amps from a class of hitherto problematic transfer functions including bandstop and even-order elliptic functions. A variety of familiar parasitic-insensitive ladder structures can be produced by matrix methods while retaining the low sensitivity properties expected of passive simulations. The method is applicable to active-RC, switched-capacitor, and digital technologies.<<ETX>>