A complementary amplifier includes an NMOS transistor coupled to a PMOS transistor in a stacked configuration. The NMOS transistor and the PMOS transistor receive and amplify an input signal. The NMOS and PMOS transistors operate as a linear complementary amplifier and provide an output signal. The NMOS and PMOS transistors may have separate bias voltages, which may be selected to overlap the low-to-high and high-to-low transitions of the transconductances of these transistors. The width and length dimensions of the NMOS and PMOS transistors may be selected to match the change in input capacitance and the change in transconductance of the NMOS transistor in moderate inversion region with the change in input capacitance and the change in transconductance of the PMOS transistor in moderate inversion region. The complementary amplifier may have an approximately constant total input capacitance and an approximately constant total transconductance over a range of voltages.