Feedforward current-mode allpass circuits

Families of complex pole filters

“…Indeed, families of complex pole allpass transfer functions can be obtained in this manner [1]. Furthermore, the voltage-mode allpass transfer functions can be converted to current-mode allpass functions with only a modest increase in circuit complexity [2]. Depending on the circuits chosen to realize the appropriate all pole transfer functions, the sensitivities of ω 0 and Q of the poles to the passive elements can easily have magnitudes of the order of 1/2 or less for both the voltage-mode and current-mode realizations.…”

“…The pole magnitudes and pole Q of the allpass realizations inherit the passive sensitivities of the appropriate lowpass circuits utilized. Sensitivities of pole positions to the finite gain-bandwidth of op amps or to bandwidths and parasitic elements of current-mode active elements such as current conveyors (CCs) are also inherited from the circuit utilized for realization of the appropriate lowpass transfer function [1], [2]. Thus, sensitivities to parameters of active elements can be low if they are low for the realization of the lowpass transfer function.…”

New families of voltage-mode and current-mode filter circuits.

“…Current-mode feedforward allpass circuit circuit for realizing current-mode allpass transfer functions with complex poles [52].…”

“…Block 3 is a first order current-mode allpass network. The overall transfer function of the circuit is The approach of applying feedforward to convert a given first order network to a useful second order network with complex poles has not been utilized before, except for the case of allpass filters presented in [34] and [52].…”