This paper presents an important component of the radio frequency transceiver called as mixer. It is a critical component and plays an important role as it has the ability for frequency conversion in RF systems. This paper focuses on double balanced ring topology of passive mixers. Ring mixer is one of the best example of passive mixers because of double balanced in nature. Double balanced is one of the most widely used topology as it suppresses both LO and RF at the output the of mixer. Various techniques have been used to improve the performance of standard topology of the ring mixer such as noise figure, linearity, conversion gain and port isolation, so these techniques have been re-viewed and compared with the previous studies. This paper also have brief discussion about a useful passive circuitry say balun and its designing with mixer as this is generally used to convert single ended signal to differential signal.