Physical analysis of the factors influencing experimental design of small-signal complementary metal-oxide-semiconductor (CMOS) amplifiers has been performed in some details. The role of the current mirror in supplying constant current source has been elucidated. It has been shown how variable resistances resulting from MOS resistors provide significant flexibility to the circuit. CMOS amplifier design employing MOS resistors yield voltage gain almost in quantitative agreement with the theoretical results. This voltage gain increases with increasing supply Voltage I ss. Further. output signal. which is out of phase of the input signal by 180 degrees, is least distorted in the amplifier circuit.