Transconductance amplifier, filter using the transconductance amplifier and tuning circuitry for transconductance amplifier in the filter

摘要

A transconductance amplifier has an input stage (10) and an output stage (11). The input stage includes a differential input circuit (MN1, MN2), a first pair of regulated cascode circuits (14a, 14b), and an input section (MP5, MP6) of a pair of current mirror circuits (15a, 15b). The output stage includes an output section (MP7, MP8) of the pair of current mirror circuits, a differential current source circuit (MN11, MN12), a second pair of regulated cascode circuits (16a, 16b), a third pair of regulated cascode circuits (17a, 17b), and a pair of amplifier output terminals (18a, 18b) connected to the output terminals of the second and third pairs of regulated cascode circuits. The output section of the pair of current mirror circuits, the second and third pairs of regulated cascode circuits and the differential current source circuit are connected in series between the voltage source and the ground.