This paper presents the design of a high-voltage differential amplifier using six different pre-input stage circuits to reduce high-voltage input levels to low-voltage signals. The proposed circuits are designed using 65 nm CMOS process technology with a nominal voltage of 2.5 V and a supply voltage of 5 V. The designs are based on stacked low-voltage standard CMOS transistors. The different pre-input stage circuits are compared to each other in terms of their circuit description, drawbacks, advantages and simulation results. The principle of the five designed pre-input stage circuits can be applied to higher voltage range input signals as well.