Suppression of Substrate Crosstalk in Mixed-Signal Complementary MOS Circuits Using High-Resistivity SIMOX (Separation by IMplanted OXygen) Wafers

We investigated the effectiveness of high-resistivity SIMOX (Separation by IMplanted OXygen) wafers to suppress substrate crosstalk. Small- and large-signal crosstalk measurements yielded similar results, which indicated that the frequency dependence of both types of crosstalk could be understood by analyzing the small-signal data. With the measured data, we constructed a model of substrate crosstalk with lumped elements, and found that the model described substrate crosstalk accurately. We also measured the crosstalk between actual digital and analog circuits. The measured and calculated data showed that high-resistivity SIMOX wafers could reduce substrate crosstalk by 5–10 dB in mixed-signal complementary metal-oxide-semiconductor (CMOS) circuits. Hence, we concluded that using high-resistivity SIMOX wafers was an effective way to suppress substrate crosstalk in mixed-signal CMOS circuits.