Patent ID: 6529078
Filing Date: 2003-03-04
Classification: H03F

Abstract:
A low-distortion transimpedance amplifier that generates an output voltage signal in response to a differential input current signal and a common-mode input current signal, comprising:a current processor that provides in-phase upper and lower current signals in response to said differential input current signal and differentially alters respective first and second amplitudes of said upper and lower current signals in response to said common-mode input current signal; and a complementary output stage having upper and lower transistors that provide said output voltage signal in respective response to said upper and lower current signals; wherein said current processor includes: a current generator that generates, in response to said differential input current signal, a first differential current signal that comprises first and second currents and a second differential current signal that comprises third and fourth currents with said fourth current substantially in phase with said first current and that differentially alters, in response to said common-mode input current signal, the amplitudes of said differential first and second current signals; a first current mirror that mirrors said first current of said first differential current signal to thereby provide a first mirrored current that is differenced with said second current of said first differential current signal to generate said upper current signal; and a second current mirror that mirrors said third current of said second differential current signal to thereby provide a second mirrored current that is differenced with said fourth current of said second differential current signal to generate said lower current signal; and wherein: said current generator includes first and second transistors that respectively provide said first and second currents to said first current mirror and third and fourth transistors that respectively provide said third and fourth currents to said second current mirror; said first and third transistors are biased to carry a first bias current; and said third and fourth transistors are biased to carry a second bias current that substantially equals said first bias current signal; distortion in said output voltage signal thereby reduced by differentially altered first and second amplitudes.