Department of Electrical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.
Considerable area occupied by capacitors is one of the main issues in the design of many ICs, especially in biomedical applications. MIM capacitor can be replaced by the MOSCAP to reduce the chip area and cost. Although the MOSCAP shows a non-linear behavior, linearization can be performed to some extent using serial and parallel compensation. In this paper, a new approach is presented, by which the impact of MOSCAP non-linearity on the THD of the circuit is reduced. The proposed technique is used in an electrocardiogram amplier. The appropriate structure for each MOSCAP of the amplier is selected by analyzing the non-linear eect of the MOSCAPs on the amplier's output linearity. The non-linear eect of MOSCAP is reduced by choosing the appropriate slopes in the MOSCAP capacitance-voltage curve. As a result, the occupied area of the amplier is reduced to less than 10 percent of the area of the amplier with MIM capacitors, while the THD is not changed considerably. The output THD is 0.65% at 60 Hz and the total power consumption is 72 nW.