Design of Linear Phase Active Distributed RC Networks

Novel active distributed RC anti-aliasing/smoothing filters are proposed. The circuits consist of two uniformly distributed RC lines with same time constant and a single amplifier (positive, unity gain). The bottom plate parasitic capacitors have no effect on the frequency characteristics, so that it is suitable for higher-frequency-range application. The magnitude sensitivity due to the variation of the element values from desired values are also investigated. The values of these sensitivities are sufficiently small. The frequency response of an experimental circuit is in good agreement with theoretical values. The proposed circuit can be fabricated by LSI process. It will be useful as the anti-aliasing/smoothing filter of a signal processor. >

Active distributed RC anti-aliasing/smoothing filters

This correspondence describes a practical active lowpass network consisting of a cascade of a uniform and an exponential line, and a single voltage-controlled voltage source of finite-source resistance. The network is simulated on a digital computer and optimized with respect to pertinent network parameters. The sensitivity of the optimized network is studied with respect to the gain of the controlled source. It is shown that this sensitivity may be reduced by increasing the taper factor of the exponential line, and that the band-elimination action of the finite-source resistance may be overcome by the uniform line.

Active filter design using exponentially tapered RC lines

Analytic equations are developed for the sensitivity functions of a class of active distributed RC networks including the sensitivity of the center frequency, the real and imaginary parts of the dominant pole, and the dominant pole Q to changes in network parameters as a function of the transformed P plane pole locations. An analytic design procedure is given for controlling the sensitivity of the dominant pole Q to changes in amplifier gain by causing the Q to be dependent upon a resistance ratio and increasing the gain. Equations are given for determining the sensitivity of Q to changes in the resistance ratio and practical limitations are also discussed. Several possible configurations for controlling the sensitivity of Q are given as well as design examples.

An analytic approach to low sensitivity design of active distributed RC networks

Two circuits are introduced which produce transfer functions that are very good approximations to second-order high-pass and bandpass functions. The circuits each require a single distributed network, an inverting amplifier, a resistor, and a capacitor.

http://ieeexplore.ieee.org/iel5/5/31141/01450098.pdf

High-pass and bandpass filters with distributed-lumped-active networks

This paper introduces a design method that allows one to find easily an active distributed RC network transfer function whose magnitude approximates the magnitude of a specified lumped low-pass transfer function. The resulting distributed RC(\overline{RC}) transfer function is a product of simple transfer functions rational in P = \cosh \sqrt{sRC} , each using a different RC product. The overall transfer function is then realized as a cascade of the realizations of the simple transfer functions using a variety of available synthesis techniques. In addition, the characterization of a distributed RC transfer function as a lumped transfer function times a delay factor, as presented herein, permits easy calculation of the transient response of the network. An example of the magnitude approximation is given together with the phase correction made by adding a delay term.

M. Ghausi

Papers

Active Distributed RC Realization of Low-Pass Magnitude Specifications