Traditionally the integrated circuits used in radio transmitters and receivers have not been developed for radio communication applications but have been adapted to them from other uses such as television or broadcast receivers. Such integrated circuits do not meet the demanding specifications of today's mobile radio designs, and this paper considers some of the problems involved in the design of integrated circuits for mobile radio applications. The paper is illustrated by reference to several circuits recently developed by Plessey Semiconductors for use in mobile transceivers.