This paper discusses Single Event Effect (SEE) mitigation techniques in readout ASICs for particle detectors in High Energy Physics (HEP) experiments. High radiation environment of such experiments results in necessity to use the SEE mitigation techniques to preserve the proper functionality of the ASIC in radiation environment. The constraints on the readout ASIC imposed by experimental conditions, mainly on power consumption, limit the range of techniques which can be actually applied. In practice an optimum set of SEE mitigation techniques needs to be found resulting in the ASIC with the required level of immunity at the given power consumption. Here we concentrate on two most popular techniques i.e. guard bands and cell redundancy. Implementation of these techniques in an example very complex readout ASIC for HEP experiment is discussed.