COMPLEMENTARY DIFFERENTIAL INPUT STAGE CIRCUIT HAVING CONSTANT TRANSCONDUCTANCE AND OPERATIONAL AMPLIFIER HAVING THE SAME

摘要

PURPOSE: A complementary differential input stage circuit having a constant transconductance and an operational amplifier having the same are provided to improve the frequency response speed by constantly maintaining the transconductance. CONSTITUTION: The circuit includes the first and second NMOS(NM1,NM2) transistors which are connected to the first and second input voltage terminals. The first level shifting device is connected to the first input voltage terminal so as to level-up a common mode voltage inputted through the first input voltage terminal. The second level shifting device is connected to the second input voltage terminal so as to level-up the common mode voltage inputted through the second input voltage terminal. The first and second PMOS transistors(PM1,PM2) receive the common mode voltage from the first and second level shifting devices. The current passing through the first and second PMOS transistors(PM1,PM2) is horizontally shifted in the left direction so that the transition area of the current passing through the first and the second PMOS transistors(PM1,PM2) is overlapped with the transition are of the first and second NMOS transistor areas.