The smart meters become an important node for managing information about electric power system so, smart-meter drags cyber security attention in this regard.  In this paper, the protocol for smart meters named as “privacy preserving billing” is used which provides authentication, non-repudiation and integrity by digital signature scheme and zero-knowledge proof. This protocol ensures secrecy and reliability of end to end communication. However, vulnerability lies in integrated circuits of smart meters that can leak sensitive information and side channel attacks (SCA), derive this information from integrated circuits(IC) while it's operating. The most well-known SCA's against smart-meters are electromagnetic radiations, timing and power analysis attacks. Due to side channel attacks integrated circuit’s physical and electrical effects broadcast information related to secret key and have emerged as a major vulnerability to security applications. SCA does not temper IC security as their non-invasiveness observes device under normal conditions. Hence, our ultimate goal is to make circuit of smart-meter immune against side channel attacks, specifically differential power analysis (DPA) attack is main focus, as it is more aggressive than other SCA’s. For this reason, we present basis for SCA resistance and concept of CMOS library. Secondly, the other concept, we introduces is CMOS-based digital isolation that provides immunity to electrical noise and external fields compared to optocouplers for smart-meters.