Patent ID: 6549074
Filing Date: 2003-04-15
Classification: H03F

Abstract:
A transconductance amplifier including an input stage and an output stage,said input stage comprising: a differential input circuit for converting a differential voltage signal applied thereto into a differential current signal; a first pair of regulated cascode circuits for adjusting output voltages of said differential input circuit depending upon a control voltage applied thereto; and an input section of a pair of current mirror circuits for mirroring the differential current signal from said differential input circuit, said differential input circuit, said first pair of regulated cascode circuits, and said input section of the pair of current mirror circuits being connected in series with each other between a voltage source and a ground, said output stage comprising: an output section of said pair of current mirror circuits; a differential current source circuit; a second pair of regulated cascode circuits for keeping output voltages of said current mirror circuit to a first bias voltage applied thereto; a third pair of regulated cascode circuits for keeping output voltages of said differential current source circuit to a second bias voltage applied thereto, output terminals of said third pair of regulated cascode circuits being connected to output terminals of said second pair of regulated cascode circuits; and a pair of amplifier output terminals connected to said output terminals of said second and third pairs of regulated cascode circuits, said output section of the pair of current mirror circuits, said second and third pairs of regulated cascode circuits and said differential current source circuit being connected in series with each other between the voltage source and the ground.