No abstract

No abstract

No abstract

No abstract

Heterodyne filters provide both tunable and adaptive filters with applications in narrow-band interference attenuation for spread-spectrum and other broad-hand communications systems. A new complex-arithmetic version of the tunable heterodyne filter offers significant hardware savings over previous versions and can more easily he implemented in adaptive filter applications.

Active filters car1 be designed using only resistors and amplifiers as the circuit elements. The reactance for these filters is obtained from the parasitic capacitances associated wit,h the amplifiers. The resonant frequency and Q of the poles and t.he location of the zeros can be controlled over a wide range by resistor feedback and feedforward circuits.General configuration for t,he first., second-and third-order filter building blocks may be used in cascade to achie\.e any desired filtering funct,ion. The basic building block is constructed from only two amplifiers and three resistors. This circuit simultaneously exhibits low.pass. high-pass, and bandpass lunctione, respectively, a t its three outputs. A simple summing network allows these out,puts to be summed t,o obtain any second. or third-order filter function.I n addition to simplifying tho circuit configuratione, the active H filter technique r e~d t s in filters which may be operated a t much higher frequencies than classical active RC filters. I n fact, experimental results confirm several orders of magnitude improvement in thc high frequency response of such filters.

No abstract

No abstract