Patent ID: 7777568
Filing Date: 2010-08-17
Classification: H03F

Abstract:
1. A folded cascode preamplifier, comprising: an open-loop high frequency differential amplifier with PMOS and NMOS transistor pairs coupled to differential inputs, where first and second resistive means are connected in series between drains of transistors of first and second current sources and the sources of each of said PMOS and NMOS transistor pairs, respectively, to force transistors of said first and second current sources into the triode region of their operation thus reducing the tail current of both PMOS and NMOS transistor pairs when active at the same time, such that when either PMOS and NMOS transistor pair is active, the overall transconductance is the same as when both PMOS and NMOS transistor pairs are active, independent of the common mode input voltage applied to said differential inputs, where the drains of both PMOS and NMOS transistor pairs are in communication with differential summing outputs; and an output stage coupled to said differential summing outputs to amplify the currents summed at said differential summing outputs.