LOW-VOLTAGE LOW-POWER OPAMP BASED AMPLIFIERS

Amplifiers operating under low-voltage and low-power conditions are st rongly limited in dynamic range and bandwidth. The maximum dynamic ran ge is limited by the supply power and the thermal noise power in resis tors. To obtain the maximum, input and output stages should be able to process signals from rail to rail. Several rail-to-rail input stages and rail-to-rail output stages biased in current-efficient class-AB mo de are presented. Also, the bandwidth is limited by the low-power cons traint. To reach the maximum bandwidth at sufficient DC gain, the effe ctivity of several frequency compensation structures is compared, such as Parallel, Miller, and Nested Miller Compensation. Finally, it is s hown that the Multipath Nested Miller Compensation combines a very hig h bandwidth with high gain, while being insensitive to process paramet ers.