1.5V 70dB 100MHz CMOS Class-AB 상보형 연산증폭기의 설계

Abstract

A 1.5V 70㏈ 100MHz CMOS class-AB complementary operational amplifier is presented. For obtaining the high gain and the high unity gain frequency, the input stage of the amplifier is designed with rail-to-rail complementary differential pairs which are symmetrically parallel-connected with the NMOS and the PMOS differential input pairs, and the output stage is designed to the rail-to-rail class-AB output stage including the elementary shunt stage technique. With this design technique for output stage, the load dependence of the overall open loop gain is improved and the push-pull class-AB current control can be implemented in a simple way. The designed operational amplifier operates perfectly on the complementary mode with 180<TEX>$^{\circ}$</TEX> phase conversion for 1.5V supply voltage, and shows the push-pull class-AB operation. In addition, the amplifier shows the DC open loop gain of 70.4 ㏈ and the unity gain frequency of 102 MHz for <TEX>$C_{L=10㎊∥}$</TEX> <TEX>$R_{L=1㏁}$</TEX> Parallel loads. When the resistive load <TEX>$R_{L}$</TEX> is varied from 1 ㏁ to 1 ㏀, the DC open loop gain of the amplifier decreases by only 2.2 ㏈.a$</TEX>, the DC open loop gain of the amplifier decreases by only 2.2 dB.