Capacitance plays a dominant role in shaping the time and frequency response of modem electronic circuits. An extensive and in-depth experimental investigation has been performed the role of various capacitors in small-signal MOSFET amplifier circuit. Particular emphasis has been given to addressing basic issues involving capacitances in MOSFET amplifiers, rather than modifying the design. Three different enhancement n-channel MOSFETs (2N700 model, referred hereafter to as MOS-1, MOS-2 and MOS-3) manufactured by Motorola Inc. have been used for the experiment. The study uncovers several important new features of the amplifiers. It indicates that in the design of small-signal MOS amplifiers, it should never be taken for granted that coupling and bypass capacitors act as short circuit and have no effect on the ac input and output voltages. In fact, they contribute to the voltage levels seen at both the input and the output port of the amplifier. When chosen judiciously for coupling and bypass operations they dictate the actual voltage gain of the amplifier at various frequencies of input signal. (C) 2002 Elsevier Science Ltd. All rights reserved.