High-precision inductorless variable equalizers with wide variable range

High-precision inductorless variable equalizers with wide variable range are developed. These are attained by an extension of the Bode-type variable transfer function to higher order functions. Inductorless realization problems for these variable equalizers may have many solutions. Two simple solutions are investigated. A practical example demonstrates an inductorless variable equalizers with a 20-dB variable range, in which approximation errors in decibels are reduced by a factor of more than 20 as compared with conventional variable equalizers.