A readout method which is suitable for high-density active microelectrode arrays used in electrophysiology experiments is presented. Amplitude modulation of consecutive channels enables simultaneous recording and transmission of the signals recorded on multiple electrodes, using a single amplifier. The physical limitation of the readout method is demonstrated to relate to the summation of the thermal noise of each recorded signal at the input of the amplification stage. Post-layout simulations of a possible circuit implementation in a 0.18 mu m CMOS technology show that five pixels connected to a single amplifier are feasible with a pitch dimension of 17 mu m, and an SNR value of 15 dB.