This manuscript describes the optimization of the front-end readout electronics for high granularity hybrid pixel detectors. The theoretical study aims at minimizing the noise and jitter. The model presented here is validated with both circuit post layout simulations and measurements on the Timepix4 Application Specific Integrated Circuit (ASIC). The analog front-end circuit and the procedure to optimize the dimensions of the main transistors are described with detail.The Timepix4 is the most recent ASIC designed in the framework of the Medipix4 Collaboration. It was manufactured in 65 nm CMOS process, and consists of a four side buttable matrix of 448 x 512 pixels with 55 mu m pitch. The analog front-end has a gain of similar to 36 mV/ke- when configured in High Gain Mode, and similar to 20 mV/ke- when configured in Low Gain Mode. The Equivalent Noise Charge (ENC) is similar to 68 e- rms and similar to 80 e- rms in High Gain Mode and in Low Gain Mode respectively. In event driven mode the incoming hits can be time stamped within a similar to 200 ps time bin and the chip can deal with a maximum flux of similar to 3.6 MHz mm-2 s-1. In photon counting mode, the chip can deal with up to similar to 5 GHz mm-2 s-1.The routine designed to optimize the Timepix4 front-end is then used to analyze the performance limits in terms of jitter and noise for Charge Sensitive Amplifiers in pixel detectors.