Today's practical applications require an amplifier with high-performance specifications. Reduce the scale of transistor sizes in operational amplifiers (op-amps) to obtain better values for the performance characteristics are important. The main objective of this study was to understand the relationship between the performance parameters of a fully differential amplifier and the channel length of the transistors. In this study, fully differential op-amp performance metrics were examined and contrasted with their channel lengths utilizing a common 1.8V power supply. The graphs were plotted using Python software. The outcome demonstrates that, as the transistor's channel length decreases, the gain and unity gain band width of the fully differential op-amp increase. This demonstrates how reducing the transistor's size allows for high amplification devices. The totally differential op-amp's power dissipation and settling time are also decreased as the transistor's channel length is decreased. This shows that in order to create fully differential op-amps that operate for long periods of time, the transistor size needs to be decreased.