I'm building a multi-channel recording system for high-impedance electrodes. One set back I'm facing right now is the charge-injection problem. After I investigate the mechanism of the charge injection, I found it's mainly come from the mismatch of the capacitance lies between the gate and drain/source from the p-mos and n-mos. If I understand it right, the control logic transit from VSS->VDD and VDD->VSS on n-mos and p-mos every time it switch on. If the capacitance is same on both end, it means the charge is injected and absorbed equally, which would not have big charge injection problem. Is their any product is matching the capacitance instead of Ron?