Realization of current-mirror filters with large time-constants

A novel scheme for realizing large time-constants in analog filters, using current-mirrors as active elements, is introduced in this paper. Instead of employing conventional capacitor multipliers, the proposed concept is based on the realization of very low values of transconductance. This has been achieved through a linear compression of the input signal in order to achieve operation of the core in a reduced bias current. The expansion performed by the output stage preserves the gain of the whole system. The validity of the proposed scheme as well as the offered benefit have been verified through simulation results using the Analog Design Environment of the Cadence software.