Operational amplifier is one of the basic blocks of signal processing applications, and the essential component for high performance mixed signal data converter and System-on-Chip(SoC) as well. As the complexity of the systems increases, low power and high performance are required, which becomes the bottle neck for further application. Therefore, the gain and bandwidth enhancement techniques become the highlights for the circuit designers. To understand the design techniques of optimizing the gain and bandwidth, this paper will focus on the current recycling techniques for performance optimization. The progresses of the techniques are listed and discussed in detail. The comparison among the structures will be given on the advantages and disadvantages. This work can provide an essential reference for the system integration.